Smart Maintenance, Analysis and Remediation of

Smart Maintenance, Analysis and Remediation of
Smart Maintenance, Analysis
and Remediation of
Transport Infrastructure
Deliverable 2.1 Specifications of nondestructive test methods for assessing
railway infrastructure
(c) The SMARTRAIL Consortium 2012
1
Project funded by the EU 7th Framework Programme under call
SST.2011.5.2-6 Cost-effective improvement of rail transport
infrastructure. Grant agreement no: 285683
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Project Information
Project Duration:
01/09/2011 – 31/08/2014
Project Coordinator:
Dr. Kenneth Gavin ([email protected])
School of Civil, Structural and Envrionmental Engineering
University College Dublin
Newstead Building
Belfield,
Dublin 4
Ireland
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Document information
Version
Date
Action
Partners
Title:
SMARTRAIL – DEL 2.1 Specification for non-intrusive test methods
for assessing railway infrastructure
Authors:
Andrew Collop and Xincai Tan (DMU)
Reviewers:
Alan O'Connor (RODIS), Kenneth Gavin (UCD)
Copyright:
© Copyright 2011 – 2014. The SMARTRAIL Consortium
This document and the information contained herein may not be copied, used or
disclosed in whole or part except with the prior written permission of the partners of
the SMARTRAIL Consortium. The copyright and foregoing restriction on copying,
use and disclosure extend to all media in which this information may be embodied,
including magnetic storage, computer print-out, visual display, etc.
The information included in this document is correct to the best of the authors’
knowledge. However, the document is supplied without liability for errors and
omissions.
All rights reserved.
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Contents
Executive Summary ......................................................................................................... 7 1 Introduction ........................................................................................................... 8 2 Guided wave inspection ....................................................................................... 10 3 4 5 6 7 8 9 10 2.1 Introduction ................................................................................................. 10 2.2 Hardware and software ............................................................................... 11 Ultrasonic Testing ................................................................................................ 23 3.1 Introduction ................................................................................................. 23 3.2 Hardware and software ............................................................................... 25 Laser ultrasonic testing ........................................................................................ 33 4.1 Introduction ................................................................................................. 33 4.2 Hardware and software ............................................................................... 34 Eddy‐Current Testing ............................................................................................ 41 5.1 Introduction ................................................................................................. 41 5.2 Hardware and software ............................................................................... 43 Magnetic encoders ............................................................................................... 61 6.1 Introduction ................................................................................................. 61 6.2 Hardware and software ............................................................................... 61 Alternating Current Field Measurement (ACFM) ................................................... 66 7.1 Introduction ................................................................................................. 66 7.2 Hardware and Software ............................................................................... 68 Acoustic Emission ................................................................................................. 76 8.1 Introduction ................................................................................................. 76 8.2 Hardware and software ............................................................................... 77 Ground penetrating radar .................................................................................... 81 9.1 Introduction ................................................................................................. 81 9.2 Hardware and software ............................................................................... 82 Falling Weight Deflectometer ............................................................................... 90 10.1 Introduction ................................................................................................. 90 (c) The SMARTRAIL Consortium 2012
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10.2 11 12 13 14 15 16 Hardware and software ............................................................................... 92 Light Weight Deflectometers ................................................................................ 98 11.1 Introduction ................................................................................................. 98 11.2 Hardware and software ............................................................................. 100 Electric Friction Cone Penetrometer Test (CPT) ................................................... 106 12.1 Introduction ............................................................................................... 106 12.2 Hardware and software ............................................................................. 108 Dynamic Cone Penetrometer ............................................................................. 113 13.1 Introduction ............................................................................................... 113 13.2 Hardware and software ............................................................................. 114 Soil Resistivity Profiling ...................................................................................... 120 14.1 Introduction ............................................................................................... 120 14.2 Hardware and software ............................................................................. 121 Rebound Hammer Test ....................................................................................... 129 15.1 Introduction ............................................................................................... 129 15.2 Hardware and software ............................................................................. 130 Laser Scanning ................................................................................................... 133 16.1 Introduction ............................................................................................... 133 16.2 Hardware and software ............................................................................. 135 17 Conclusions ........................................................................................................ 141 18 References ......................................................................................................... 142 (c) The SMARTRAIL Consortium 2012
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Executive Summary
Non-destructive test (NDT) methods play an essential role in rail track assessment and
maintenance. As a task in the EU funded project SMARTRAIL, this report presents
surveyed specification data on the state-of-the-art NDT methods available for assessing
railway infrastructure.
The aims of this report were to:

Provide the SMARTRAIL project with NDT data reference for investigation into
structure safety modelling;

Review specification on NDT methods from literature; and

Provide referenced data for NDT in infrastructure maintenance.
The survey data were desk-based, and the literature resources included papers from
journals and conferences, products descriptions from NDT companies online, reports of
projects, etc. Since railway infrastructure consists of various layers of materials, various
NDT methods have been developed for suitability for the different layer materials. Typical
specification data for NDT methods are presented in the report:

For rail: guided wave inspection, ultrasonic testing, laser ultrasonic testing, eddycurrent testing, magnetic encoders, alternating current field measurement, and
acoustic emission.

For ballasts: ground penetrating radar, falling weight deflectometer, and light weight
deflectometers.

For subgrades: electric friction cone penetrometer test, dynamic cone penetrometer,
and soil resistivity profiling.

For concrete tunnels, bridges and sleepers: rebound hammer test and laser
scanning.
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1
Introduction
Regular inspection and maintenance of railway infrastructure is always one of the key tasks
for the rail industry. Non-destructive testing (NDT) methods have been developed to directly
measure situations and conditions of railway infrastructure including rail defects, track
deterioration, and geometry changes. NDT does not change its timing or processing
characteristics, but usually involves additional hardware that collects timing or processing
information and processes.
In order to understand current NDT methods, as well as develop and apply NDT advanced
technologies, the EU funded project SMARTRAIL has made a survey in the NDT area. The
objectives of the survey were to:

Benchmark on advances of NDT methods in literature;

Collect example specification data of typical NDT methods;

Provide a technical reference of specification for design and analysis in rail
infrastructure.
In addition to rail defects, failures of railway infrastructure occur within all layers of the track,
e.g., ballast fouling, subgrade and/or trackbed structural component failure. Thus railway
infrastructure assessment will include measurements, inspections and evaluations on track
geometry, ballast coverage, detection of rail flaw, corrugation, rolling contact fatigue
cracking and the like.
In some EU funded projects including INNOTRACK (2008), PM’n’IDEA (2009), WIDEM
(2008), surveys on NDT were made, although they mainly focused on rails and detailed
specification data were few.
This survey will focus on specification details for rail infrastructure including rail. The data
collections were mainly desk-based, and the resources include various publications and
documents from journals, conferences, reports of projects, books, and websites. This report
focuses on specification data although the corresponding test methods, equipment and
principles will be sometimes also described.
The report can be divided into several blocks as follows:

NDT methods for rails will be provided in Chapters 2-8: guided wave inspection,
ultrasonic testing, laser ultrasonic testing, eddy-current testing, magnetic encoders,
alternating current field measurement, and acoustic emission.

NDT methods for ballasts will be given in Chapters 9-11: ground penetrating radar,
falling weight deflectometer, light weight deflectometers, and laser scanning.

NDT methods for subgrades will be presented in Chapters 12-14: electric friction
cone penetrometer test, dynamic cone penetrometer, and soil resistivity profiling.

NDT methods for concrete tunnels, bridges and sleepers will be in Chapter 15:
rebound hammer test.
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
NDT method for comprehensive evaluation will be provided in Chapter 16: laser
scanning.
This report will summarise the survey data. After this introduction, the specification details
on the above typical methods will be described. Finally, conclusions will be drawn.
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2.1
Guided wave inspection
Introduction
The guided wave inspection method is one of latest methods in the NDT field. It uses
structure-borne ultrasonic waves that propagate along the structure confined and guided by
its geometric boundaries. This allows the waves to travel a long distance with little loss in
energy. Nowadays, the guided wave testing is increasingly used to inspect and screen rails.
Fig.2-1 Comparison of guided wave inspection with conventional ultrasonic inspection
(Guided Ultrasonics Ltd. 2013)
Applications
 Rail flaw detection
 Aerospace applications
 Gas cylinder inspection
 Bridge cable inspection
 Pipeline inspection
Transducers for generating guided waves:
 Piezoelectric transducers: angle beam, array
 Electromagnetic acoustic transducers (EMATs): shear horizontal waves in plate,
lamb wave in plate, torsional waves in pipe, longitudinal waves in pipe
 Magnetostrictive transducers: torsional waves in pipe, shear horizontal waves in
plate
Advantages:
 For piezoelectric transducers: directional control, Permanent installation, low cost.
 For electromagnetic acoustic transducers (EMATs): lamb and SH-wave generation,
T-wave and L-wave generation, no couplant required, possibility for non-contact, bidirection.
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
For magnetostrictive transducers: lamb and SH-wave generation, T-wave and Lwave generation, possibility for non-contact, directional control/bi-directional,
permanent installation
Limitations
 For piezoelectric transducers: multiple installation steps, many acoustic interfaces,
100% couplant required.
 For electromagnetic acoustic transducers (EMATs): high voltage pulsers required,
comparable low SNR, higher cost instrumentation, bi-directional, conductive
materials only.
 For magnetostrictive transducers: bi-directional, conductive materials only, bonding
often required, multi-step sensor installation, ferromagnetic materials only.
2.2
Hardware and software
Fig.2-2 Wave echo path of a rail (Zumpano and Meo 2006)
2.2.1
Case one: MsS System
As an example, specification of MsSR System (Guided Wave Analysis LLC 2013) is given
here.
Fig.2-3 The MsS System: electromagnetically generating and receiving low-frequency
ultrasonic guided waves (Guided Wave Analysis LLC 2013)
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Fig.2-4 MsSR 3030R System (Guided Wave Analysis LLC 2013)
Specification of MsSR 3030R System (Guided Wave Analysis LLC 2013) is:

Two channel transmitters and receivers for controlling the wave propagation
direction;

120 V or 240 V AC, 50/60 Hz, power or internal battery operated; the internal battery
supplies power to both equipment and computer for operating more than 2 days in
normal operation with more than 50 inspection locations;

Wide frequency range operation: 5 kHz to 250 kHz;

The system has band pass filter at 16, 32, 45, 64, 90, 128, 180, and 250 kHz;

The MsS probe can be installed with 25 mm or higher clearance around the pipe
and 75 mm clearance along the pipe;

The MsS probe can be installed if the pipe is accessible by more than 60 mm
around the pipe circumference. The heat tracer lines do not need to be lifted;

Two operation modes
-
pulse-echo mode: normal guided wave inspection and monitoring,
-
pitch-catch mode: guided wave inspection of high-attenuation pipe;

Time-corrected gain (TCG) function that increases signal-to-noise ratio of longdistance signal;

Probe is very light (less than 0.8 kg for 24-inch pipe testing probe);

Light instrument (12.5 kg);

Software functions
-
Sorting out false calls due to multiple reflections,
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2.2.2
-
Multi-frequency data analysis for finding different size of defects,
-
Spectrogram data display for showing frequency response of indication,
-
Automatically finding indications.
Case two: Sonatest EMAT transducers
Fig.2-5 Sonatest EMAT transducers
Applications: Boiler tubes with oxidised & corroded surfaces; Incinerators & refuse
burners; Nickel/Permalloy plated; ferrous metals; Superheated tubes with scale up to 57mm thick; High temperature operations.
Features of Sonatest EMAT transducers

A non-contact shear wave Electro Magnetic Acoustic Transducer.

Construction consists of a plastic case with side entry cable and knurled grip, or
rugged brass case with integral adjustable wear/distance ring.

Measures the thickness through oxidized and corroded surfaces.

Does not require any couplants (oil or water).

No surface grinding required and therefore no further damage to materials under
inspection.

Accuracy of EMAT ± 0.1mm (if used with Sonatest MS 340 Digital Flaw Detector).

Neodymium-Iron-Boron Magnet for ultra high field strength.
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Table 2-1 Specifications of Sonatest EMAT transducers (Sonatest Plc 2013)
Type
Size
Cable
Frequency
Connector
Weight
Pulse Duration
EMAT 5-0.5 STD Plastic Case
18-22 mmØ x 20 mm long
1.8 meters long (side entry)
5 Mhz ±10%
BNC
62g
1.0s *(Sonatest MS340)
EMAT 5-0.75 SO Brass Case
28 mmØ x 58 mm long
1.8 meters long (top entry)
5 Mhz ±10%
BNC
122g
1.0s *(Sonatest MS340)

Calibration of Sonatest EMAT transducers (SONATEST PLC 2013)Gate 1 +ve (30%
height)

Measurement mode Depth, H-U-D on distance, Peak mode*

Single probe operation

Frequency 5MHz

Detect FWR

Set contour to 3

Set TX pulse width to minimum (20ns)

Adjust damping to achieve maximum amplitude from returned signal

200 volts (400V NOT suitable)

Velocity = 3230m/s

Range = 10mm

Adjust gain until echo height is about 80% (will be high gain about 100dB)

Adjust probe zero until thickness reads same as test tube thickness
2.2.3
Case three: G-Scan and MsS System
Product Specifications (Guided Ultrasonics Ltd. 2013)

Capable of testing more than 50m of rail in each direction (i.e. more than 100m of
rail per test)

Typical test time less than 1 minute

Can detect significant transverse defects in the head, base and web

Can detect defects in alumino-thermic welds and test through multiple welds

Rapid deployment with integrated pneumatic clamping mechanism

Single unit with no trailing wires
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
USB interface to laptop or PC for data storage, backup and additional processing

Integrated rechargeable battery for more than 8 hours use

Integrated GPS for automatic site location

Simple user interface

Fully automated test sequence

Full technical audit trail for all data collected.
Table 2-2 Abbreviated Technical Specification for GUL’s Wavemaker Pipe Screening
System (Silverwing Middle East LLC 2013).
Number of
Transducer
Channels
32
Screen
Maximum number
of averages
256
Communication
protocol
USB (Mass Storage)
Maximum sample
range
640ms (approx.
950m)
Supported Op.
Systems
Window 2000, XP
Receiving gain
range
10-120 dB
Expandability
Built in USB Host
G3 Weight
8 kg
Capacitance check
0.1 nF accuracy on all
channels
G3 Dimensions
44x14x40cm
Weight of 3 inch ring
(complete)
6 kg
Run time on one
battery charge
10 hours typical
use
Weight of 24 inch ring
(complete)
15 kg
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2.2.4
Case four: TT Transducer Tester
Fig.2-6 The Rapid Controls model TT Transducer Tester interfaces with multiple types of
magnetostrictive transducers and displays position and status information from the
transducer. (Easiest Engineering & Trading Ltd 2004)
Features of TT Transducer Tester (Easiest Engineering & Trading Ltd 2004):

Compatible with Start/Stop, Start/Stop Trailing Edge, PWM, Neuter, SSI, Analog,
and MTS protocol CANbus, CANOpen, and Profibus DP sensors

Optionally battery powered for easy testing at any location

2 line x 20 character backlit LCD display for magnetostrictive transducers

Capable of calibrating MTS SSI transducers at 1200 or 4800bps

Programmable analog output for data logging

Six button front panel keypad to accommodate front panel setup

Removable 5mm Phoenix type screw terminals for connections

2+ hour battery life while powering a transducer

Setup stored in non-volatile EEPROM memory
Specifications of TT Transducer Tester (Easiest Engineering & Trading Ltd 2004):

Power requirements: less than 1A from 90-264VAC at 47-440Hz

SSI, Start/Stop, and PWM outputs are RS422 differential

SSI, Start/Stop, and PWM inputs drive an optoisolator

Start/Stop single-ended (neuter) level must be at least 1.2V

Analog output is scalable to any position range
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
Switched 24V sensor power is current limited to 200mA

Optional +/-15V sensor power

Minimum of 1 hour battery life (while powering one transducer)

Housed in plastic enclosure: 10.5x9x5 inches without battery, 10.5x9x7 inches with
battery

Weight: 5 pounds without battery, 10 pounds with battery
2.2.5
Case five: Temposonics Magnetostrictive Sensors
Features of Temposonics Magnetostrictive Sensors (MTS Systems Corporation 2010).

Linear, Absolute Measurement

LEDs For Sensor Diagnostics

Non-Contact Sensing Technology

Non-Linearity Less Than 0.01%

Repeatability Within 0.001%

Direct 24/25/26 Bit SSI Output, Gray/Binary Formats

Synchronous Measurement for Accurate Velocity/Acceleration Calculations
Fig.2-7 Temposonics Magnetostrictive Sensors (MTS Systems Corporation 2010).
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Table 2-3 Specifications of Temposonics Magnetostrictive Sensors (MTS Systems
Corporation 2010).
Parameters
OUTPUT
Measured output
variables:
Resolution:
Update Rate
Measuring length:
Measurments/Sec:
Non-linearity:
Repeatability:
Hysteresis:
Outputs:
Length:
Baud rate:
Stroke length:
Distance between
magnets::
ELECTRONICS
Operating voltage:
Specifications
Position, or position difference between 2 magnets, or velocity,
internal temperature
0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm
300 750 1000 2000 5000 mm
3.7 3.0 2.3 1.2 0.5 kHz (Up to 10 kHz for high-speed update
option)
< ± 0.01% full stroke, (minimum ± 40 μm) (Linearity Correction
Option (LCO) available)
< ± 0.001% full stroke (minimum ± 2.5 μm)
< 4 μm (2 μm is typical)
Interface:
Synchronous Serial Interface (SSI) (RS-422 type differential signal
pairs)
Data format:
Binary or gray, optional parity and error bit, optional internal
temperature.
Data length:
8 to 32 bit
Data speed (Baud rate):
70 kBd to 1 MBd, depending on cable length (see below):
<3
<50
<100
<200
<400 m
1.0 MBd <400 kBd <300 kBd <200 kBd <100 kBd
Range (Profile style):
25 to 5080 mm (1 to 200 in.)
Range (Rod style):
25 to 7620 mm (1 to 300 in.)
Range (Flexible style):
255 to 10,060 mm (10 to 396 in.)
(Contact factory for longer stroke lengths)
75 mm (3 in.) minimum for 2 magnet differential output
* With standard monoflop of 16 μs
+24 Vdc nominal: -15% or +20%
Polarity protection: up to -30 Vdc
Overvoltage protection: up to 36 Vdc
Current drain: 100 mA typical
Dielectric withstand voltage: 500 Vdc (DC ground to machine
ground)
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Table 2-4 Specifications of Temposonics Magnetostrictive Sensors (MTS Systems
Corporation 2010). Continued
Parameters
ENVIRONMENTAL
Operating
conditions:
EMC test:
Shock rating:
Vibration rating:
Specifications
Operating temperature:
-40 °C (-40 °F) to +75 °C (+167 °F)
Relative humidity: 90% no condensation
Temperature coefficient: < 15 ppm/ °C
Emissions: IEC/EN 50081-1
Immunity: IEC/EN 50082-2
IEC/EN 61000-4-2/3/4/6, level 3/4
criterium A, CE qualified
100 g (single hit)/
IEC standard 68-2-27 (survivability)
15 g (30 g with HVR option)/
10 to 2000 Hz, IEC standard 68-2-6 (operational)
Wiring
Connection type:
7-pin male D70 (M16) connector, 10-pin male MS connector or
integral cable
PROFILE STYLE SENSOR (MODEL RP)
Electronic head:
Aluminum housing with diagnostic LED display (LEDs located
beside connector/cable exit)
Sealing:
IP 65
Sensor extrusion:
Aluminum (Temposonics profile style)
Mounting
Any orientation. Adjustable mounting feet or T-slot nut (M5
threads) in bottom groove
Magnet types:
Captive-sliding magnet or open-ring magnet
ROD STYLE SENSOR (MODEL RH)
Electronic head:
Aluminum housing with diagnostic LED display (LEDs located
beside connector/cable exit)
Sealing:
IP 67 or IP 68 for integral cable models
Sensor rod:
304L stainless steel
Operating pressure:
350 bar static, 690 bar peak (5000 psi, 10,000 psi peak)
Mounting:
Any orientation. Threaded flange M18 x 1.5 or 3/4 - 16 UNF-3A
Typical mounting
45 N-m (33 ft. - lbs.)
torque:
Magnet types:
Ring magnet, open-ring magnet, or magnet float
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Fig.2-8 Sensor input of Temposonics Magnetostrictive Sensors (MTS Systems Corporation
2010).
Fig.2-9 Timing Diagram of Temposonics Magnetostrictive Sensors (MTS Systems
Corporation 2010).
Fig.2-10 Logic Diagram of Temposonics Magnetostrictive Sensors (MTS Systems
Corporation 2010).
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Fig.2-11 Advanced communication and programmability for Temposonics Magnetostrictive
Sensors (MTS Systems Corporation 2010).
Table 2-5 Standard magnet options for Temposonics Magnetostrictive Sensors (MTS
Systems Corporation 2010).
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2.2.6
Case six: AKR 1224 Detector
Fig.2-12 AKR 1224 Detector used for guided wave testing (Gurvich et al. 2006 and 2004)
The main characteristics of AKR 1224 (Gurvich et al. 2006 and 2004)

Maximal tested distance 50 m

Dead zone at detection of rail’s butt-end not more than 0.5 m

Distance counting discreteness 0.01 m

The duration of work from accumulator not less than 8 hours

Operation temperature range – 20 to + 45° С

Sizes of electronic unit 245 x 120 x 50 mm

Sizes of antenna array 258 x 92 x 39 mm

Weight of electronic unit 770 g

Weight of antenna array 850 g
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3.1
Ultrasonic Testing
Introduction
In ultrasonic testing (UT), an ultrasound transducer connected to a diagnostic machine is
passed over the object being inspected. The transducer is typically separated from the test
object by a couplant (such as oil) or by water, as in immersion testing. UT is often
performed on steel and other metalsand alloys, though it can also be used on concrete,
wood and composites, albeit with less resolution. It is an important form of NDT used in
railway industry.
Fig.3-1 Rail inspection with normal ultrasonic head (0°) and angle ultrasonic heads (45°,
70°) (Jemec and Grum 2010).
Fig.3-2 SNCF ultrasonic inspection train (left), ultrasonic probes support (right) (Djeddi and
Aknin 2008).
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Fig.3-3 various ultrasonic facilities for rail inspection (Jemec and Grum 2010).
Applications:

Railway - track junctions in manganese steel (crack detection and sizing)

Aerospace - composite testing

Steel production - large castings, hot and cold rolled steel

Engineering - welds and joints

Energy - austenitic welds, drive shafts etc.

Pipe inspection
Advantages
Based on air-coupled ultrasound generation and air-coupled detection using
microphones, this technique is completely noncontact and non-destructive.
Therefore it is a candidate for high-speed measurement and evaluation.
 Advantages
 Sensitive to both surface and subsurface discontinuities
 Penetration depth is better than other NDT methods
 With pulse-echo, access to only one side is needed
 Highly accurate in regards to reflector size, shape, and location
 Minimal part preparation
Limitations (NDT Resource Centre 2003)

Surface must be accessible to transmit ultrasound;

Skill and training is more extensive than with some other methods;

It normally requires a coupling medium to promote the transfer of sound energy into
the test specimen;

Materials that are rough, irregular in shape, very small, exceptionally thin or not
homogeneous are difficult to inspect;
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
Cast iron and other coarse grained materials are difficult to inspect due to low sound
transmission and high signal noise;

Linear defects oriented parallel to the sound beam may go undetected;

Reference standards are required for both equipment calibration and the
characterization of flaws.

Surface must be accessible to transmit ultrasound

More training required relative to other methods

Coupling medium is normally required to promote transfer of sound

Has difficulty inspecting rough, small, or irregularly shaped objects

Linear defects parallel to sound beam may go undetected

Speed
Because the device will be designed for noncontact measurements, it can be implemented
in a running vehicle.
Costs
Cost depends on the size of the unit but should be less than $50,000.
3.2
Hardware and software
The hardware for ultrasound generation consists of a function generator, an amplifier, and
several ultrasonic transducers that build a line source; the hardware for ultrasound
detection consists of microphones, preamplifiers, and a data acquisition system.
3.2.1
Case one: DEFECTOBOOK® DIO 1000 PA
As an example, Starmans’ latest Ultrasonic Flaw Detector Defectobook® combines features
of conventional ultrasonic with the power of the Phased Array. The new advanced
DEFECTOBOOK® DIO 1000 PA digital ultrasonic flaw detector is now augmented with
phased array imaging capabilities. It is combining all features of conventional ultrasonic with
power of phased array.
Using the latest generation of electronic components and microprocessors we have brought
the thinnest, lightest and really portable phased array instrument, which makes your
inspection easy and fast. The standard configuration is 16 parallel (in preparation 32
parallel), and with extendable module 16:64 and 16:128. The instrument also combines
digital design with the detailed dynamic echo information, using sampling rate 200 MHz, 12bit.
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Fig.3-4 DEFECTOBOOK® DIO 1000 PA digital ultrasonic flaw detector (Starmans 2013)
Table 3-1 General specification for DEFECTOBOOK® DIO 1000 PA digital ultrasonic flaw
detector (Starmans 2013)
Display Screen
6“ TFT LCD, 1024x768 pixels, 60 Hz update rate
Display dimensions
99x130mm
True sampling rate
200MHz, 12-bit
Dimension (W x H x D)
224 mm x 188 mm x 34 mm
Weight
1.3 kg with battery
Battery
Built-in Li-Ion battery 3.6V, 16Ah
Battery operating time
Up to 10 hours
Languages
Selectable, user-defined custom language
External Power Supply
for Adaptor
AC 80V~240V 50Hz/60Hz
Data Memory
4 – 16GB (up to 40000 A-Scans)
Warranty:
2 years, optional 3 years
Environment Tests
Operation Temperature
-10°C~50°C
Storage Environment
-40°C~70°C
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Table 3-2 Specifications of conventional and PA modes for DEFECTOBOOK® DIO 1000
PA digital ultrasonic flaw detector (Starmans 2013)
Conventional Mode
PA Mode
USB Connector
One – Host USB
One – Host USB
Encoder Connector
A, B – pulses, TTL 5V, Start
A, B – pulses, TTL 5V, Start
Ethernet Connector
External (optional on USB)
External (optional on USB)
High Speed Parallel
and TTL Port
(optional)
Alarm outputs, trigger in/out
control
N/A
Analog Output
Presence of echo in Gate,
Thickness, Position of Echo
flank in Gate, EchoStart +
AUX
N/A
A/D Sampling
Frequency
200 MHz
Probe connector
Mini Lemo®
Number of Channel
1 channel
16 channels
Scan Type
B-scan Thickness / RGB
amplitude
Linear / Sector
Focal Law quantity
N/A
max. 512
Scan Angle Range
N/A
Linear: -45° ~ +45°
Sector: -80° ~ +80°
50MHz
Molex - support up to 32element probe. Probe and
wedge data shall be inputted
manually.
Linear: For setting scan
aperture, angle focus point,
waveform, start element,
element step, number of scan
line.
Sector: For setting scan
aperture, start angle, end
angle, focus point, and
waveform.
Instant focus point changes
based on auto re-calculation.
Scan Setup
N/A
Range
0~29000mm for PRF 100Hz
(Steel longitudinal wave)
0~29000mm for PRF 100Hz
(Steel longitudinal wave)
Material Velocity
1~19999 m/s
1~19999 m/s
Display Delay
-25~29000mm
(Steel longitudinal wave)
-25~29000mm
(Steel longitudinal wave)
Auto Transducer
Calibration
Zero offset and velocity
Zero offset and velocity
Units
mm, inch, µs
mm, inch, µs
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Refracted Angle
Fixed settings of 0°, 30°, 45°,
60°, 70°; variable 10°~90° in
0.1° steps for calculations
Test Modes:
Pulse Echo, Dual, ThroughTransmission, EMAT
Probe Delay Range
Gate Monitors
Alarms
Cursors
N/A
Pulse Echo, ThroughTransmission
-10µs~4800µs with 5ns
resolution
-10µs~4800µs with 5ns
resolution
Four Gates: Floating gate,
Interface gate, Measuring
gate, Back-wall attenuator
Four Gates: Floating gate,
Interface gate, Measuring
gate, Back-wall attenuator
Selectable threshold
positive/negative or minimum
depth modes
N/A
Selectable threshold
positive/negative or minimum
depth modes
Radius, Angle
Main technical specification for DEFECTOBOOK® DIO 1000 PA digital ultrasonic flaw
detector (Starmans 2013):
Display: Color TFT sunlight, 1024 pixels (W) X 768 pixels (H)
Gain control: 110 dB Max and reference gain control level sensitivity feature with 6 dB, 1
dB, 0.5 dB and 0.1 dB selectable steps
Auto Transducer Calibration: Automated calibration of transducer, zero offset and/or
velocity
Reject: 0% to 80% of full scale in 1% increments
Material Velocity: From 100 to 15240 m/s in steel
Range: Standard 1 mm to 60,000 mm
Pulser Type, User Selectable: Tunable square wave, negative spike excitation, burst
Rectification: Full Wave, Half Wave Positive or Negative, and rectified RF settings
Analog Bandwidth: 0.5 MHz to 30 MHz at 3 dB
Filters: Broadband, Narrowband, or Custom Selectable Low and High Pass Filters 1 MHz,
2 MHz, 2.25 MHz, 4 MHz, 5 MHz, 10 MHz
Operating Temperature: -10 C to 50 C
Storage Temperature: -40 C to 70 C
Power Requirements: AC Mains: 100-120 VAC, 200-240 VAC, 50-60 Hz
Battery: Built-in and external rechargeable LiIon battery pack rated at 3.6 V at 16 Ah
USB Communications Port: Hi-speed interfacing with PC
Communications ports:

RS232
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
Ethernet

Wireles Ethernet

Bluetooth
Memory: 4 up to 16GB
Bscan input: Encoder, A,B pulses, start, TTL 5V, Encoder supply switchable 5V
Dimensions: 224 x 188 x 37 mm
Display dimensions: 99 x 130 mm
3.2.2
Case two: DEFECTOBOOK® DIO 2000
DEFECTOBOOK® DIO 2000 system (Starmans 2013) is another case on ultrasonic
testing.
DIO 2000 General Features
The system’s ultrasonic channels are designed as independent electronic plug-in units
(modules) with their own microprocessor control and signal processing. The plug-in units
(size 100 x 160 mm) are located in frames. Every frame may contain 16 units. Four frames
may be assembled in a 19" rack with power supply built-in. In this way the maximal system
range consists of 64 channels.
The control system and the data evaluating system of DIO 2000 consists of an industrial PC
(Pentium IV), 17" SVGA Color monitor, also of industrial type, and the appropriate software
under MS Windows 2000. This control system is very user friendly, because of applying the
well-arranged menu.
In order to assure the UT reliability, a synchronization unit may be assembled into the
system and a unit for probe localization on the surface of the specimen under test. The
output of the device may control a defect marker and, according to the customer’s option,
an acoustic and luminous signalization. As a matter of course there are printing facilities
(ink-jet or laser) for recording the flaw distribution in the material under test (B- and C-scan,
thickness or tolerances) or/and an overview during a time interval.
According to the customer's requirements it is possible to operate an acoustic alarm.
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Fig.3-5 DIO 2000 system ultrasonic units (Starmans 2013)
DIO 2000 Channel Unit
Each channel is created by an independent module (card with electronic circuits) containing
all components as a complete ultrasonic flaw detector with
-
adjustable pulse repetition rate;
-
adjustable amplifier gain and band filters;
-
digital signal processing DSP (digital filters, averaging and further functions);
-
three gates with a set-up alarm;
-
measuring of echo height maximum, minimum, average, echo extent and
graphic processing;
-
2 analogue outputs (amplitude and time) for C-scan;
-
automatically renewable freeze mode;
-
maximum freezing;
-
external and internal synchronization with adjustable time shift;
-
possibility of connecting an extern power transmitter to every channel;
-
possibility of using probes with internal preamplifier.
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Transmitter:
-
location: in each channel unit
-
transmitted pulse: up to 250 V at 50 Ω loading
-
transmitted pulse width: 60 ns up to1 μs
-
triggering of the transmitted pulse: internal or external
-
synchronization of the transmitted pulse: automatic PC controlled
-
transmitted pulse shift: 0 ns to 10 ms
-
max. transmitter repetition rate: 10 kHz
-
operation facilities: normal or TR probes for frequency range from 1 to 20
MHz
-
transmitter output impedance: adjustable - in steps, from 30 to 1000 Ω.
-
Location: in every channel unit
-
Max. input echo signal voltage: 1 Vp-p
-
Processable echo signal voltage: < 1 Vp-p to > 0.1 mVp-p at 100% screen
height
-
Adjustable dynamic: +20 dB to +99.9 dB
-
Gain linearity: 1 %
-
Receiver frequency range: 0.5 MHz to 20 MHz (for -3 dB)
-
Input receiver impedance: adjustable from 30 to 1000 Ω
Receiver:
Digital Data Processing:
-
Evaluation: by the built-in microprocessor, amplitude and time comparison,
leading edge or peak value evaluation in selected gate, statistic elimination
of interference, data compression, A-scan
-
Noise suppressor: 0 to 80 % screen height
-
Gates: 3
-
Threshold levels: 1 in every gate - adjustable
-
Gate triggering: synchronized by the transmitter or selected echo leading
edge (“echostart“)
Measuring Accuracy:
-
Amplitudes for flaw detection: ±1 % relative to 10 MHz signal
-
Time size measurement: ±1 μm relative to sound propagation velocity (in
ferritic steel) for ultrasonic frequency of 15 Hz
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-
Entering of measuring parameters: by means of a PC trough RS 232; 422,
USB setting of the whole testing system: “manual inspection” by a PC or by
pre-selected parameters stored in the PC (set at some preceding testing).
DIO-2000 Unit Versions
SF
DIO2000 19” 1-16 CH SF is the most used type with the frequency band 1-15 MHz
containing four frames with 16 channels each, i.e. this type may be broadened till to
64 channels. The automated installations (see thereinafter) supplied for inspection
of steel bars, aluminium blocks, axles and wheels for railway vehicles and others is
equipped with this DIO 2000 type.
HF
DIO2000 19” 1-16 CH HF is the high frequency type with the frequency band from
15 to 60 MHz, which is being used for inspection of thin components or thickness
measurement.
LF
DIO2000 19” 1-8 CH LF+BP is the type provided with a power transmitter foreseen
to air coupled inspection of composites, wood, concrete, ceramics and others. Also
four frame may be connected with four channels too. In this way for low frequency
application with 32 channels in the band from 10 kHz to 1 MHz.
DIO-2000 Connection and Casing
Small Size Version
There are cases, where fewer channels are needed. For such purposes, low cost version
DIO 2000 with 3 channels only is available.
It is a portable industrial which may be used without PC also, e.g. for defect marking and
control of other devices. The modifications are the same as said above in connection with
the DIO 2000 compact version.
Software
The software depends on the data acquisition system used. It can be LabView, Matlab, or
any other common data acquisition software. The data analysis software can be written in
Matlab.
DIO-2000 Software is from manufacturer. The large screen of a 17” monitor allows
simultaneously displaying of several A-scans and of several parameters and channel
windows.
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4
Laser ultrasonic testing
4.1
Introduction
Laser ultrasonic testing (LUT) is a remote, noncontact extension of conventional, contact or
near-contact ultrasonic testing (UT). It induces high frequency ultrasound in the material,
leave a very small footprint so that it can be applied to irregular geometries, and reach
access restricted areas via fibre optics. Since the laser-based system is not restricted to
applying ultrasonic energy to the rail from the top of the railhead, defects such as
transverse and vertical head defects under damaged rail surface along with those defects
located at the rail web and base can also be reliably detected. Moreover, since the
ultrasonic transmission does not depend on contact conditions, inspection speed can reach
up to 60 mph (96.5 km/h).
Fig.4-1 a laser ultrasonic system for rail inspection (Intelligent Optical Systems 2013,
Nielsen et al. 2004, Cerniglia et al. unknown)
Application Examples: composite flow detection, bond evaluation, weld inspection,
coating thickness measurement, crack sizing, grain size measurement, thickness
measurements, defect detection.
Materials Inspected: steel, cast iron, ceramics, glass, composites, semiconductors.
Industries Served: automotive and railways, semiconductor packaging, electronic
component, steel and cast iron manufacturing, aerospace, oil and gas pipeline,
shipbuilding, glass packaging.
Advantages

Remote, non-contact, reconfigurable

Can scan measurement head or sample

Proven at speeds ≥ 5 m/sec
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
Proven at temperatures ≥ 2000°F

High bandwidth operation

High spatial resolution

Micrometer thickness accuracy

Small contact area on sample

The component's surface does not require preparation.

Cost effective
Limitations:

The transmitted ultrasonic energy is relatively low.

The technique is only applicable to materials with good optical absorption properties

High Initial cost

Less Sensitivity

Inspection varies with material/coating

Cannot penetrate honeycomb stiffened materials

No through transmission
4.2
4.2.1
Hardware and software
Case one: LUKS-1550-TWM Laser Ultrasonic Kit
The IOS LUKS-1550-TWM Laser Ultrasonic Kit for Starters is designed to provide all
components necessary for laser ultrasonic inspection. It includes the innovative AIR-1550TWM laser ultrasonic receiver, having an ideal combination of sensitivity and response time
and operating at the eye safe wavelength of 1550 nm. The fiber-coupled measurement
head is small and reconfigurable. With added integration, the LUKS-1550-TWM can
perform process monitoring and inspection in factory conditions and in-service inspection in
the field.
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Fig.4-2 Laser Ultrasonic Kit for Starters (LUKS-1550-TWM) (Intelligent Optical Systems
2013). The receiver and probe laser are mounted in a 19” rack; and the remote
measurement head is fiber coupled.
Table 4-1 Specifications of Starters (LUKS-1550-TWM) (Intelligent Optical Systems 2013)
COMPONENTS
Receiver
Probe Laser
Options
Generation Laser
Scanning System
Data Acquisition
and Control
Accessories
LUKS-1550-TWM
AIR-1550-TWM
Continuous-wave, single-frequency fiber laser at 1550 nm
Power: 400mW-2W
Q-switched Nd:YAG at 1064 nm
Pulse width: 10 ns; pulse energy: 50, 200 or 400 mJ
Optional: Fiber Delivery
Two linear stages and controller; range of specifications available
LaserScan™ software: Scanning system motion control, data
acquisition, processing and display A-scan, B-scan, C-scan;
specialized processing
Desktop computer with DAQ card: PC running Windows XP Pro
Laser eye safety goggles; lenses and mirrors for generation beam
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Fig.4-3 LaserScan™ software for Laser Ultrasonic testing (Intelligent Optical Systems
2013)
4.2.2
Case two: AIR-1550-TWM Laser Ultrasonic Receiver
The AIR-1550-TWM Laser Ultrasonic Receiver represents the state-of-the-art in noncontact laser ultrasonic testing. The AIR-1550-TWM is the first laser ultrasonic receiver
operating at the telecom and eye-safe wavelength of 1550 nm. The AIR-1550-TWM
includes a compact fiber-coupled measurement head. This sensor head enables remote
measurement and is ideal for use with complex configurations or where measurement
access is limited. The non-contact measurement capability of laser ultrasonics and its
immunity to test-piece temperature and motion make it ideal for factory use. The AIR-1550TWM is available configured for factory applications with optional ruggedized measurement
head and fiber optic cables.
Fig.4-4 Laser Ultrasonic Receiver (AIR-1550-TWM) and Measurement Head (Intelligent
Optical Systems 2013)
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Table 4-2 Specification of Laser Ultrasonic Receiver (Intelligent Optical Systems 2013)
Model
Surface Displacement
Sensitivity
Detector Bandwidth
Measurement Type
External Probe Laser
Requirement
FHY Fiber Measurement
Head
Optional Guide Laser Beam
Analog Output
Electrical Requirements
Alignment Signal
Dimensions
4.2.3
AIR-1550-TWM
4 x 10-7 nm rms (W/Hz)1/2
125 MHz
High Sensitivity, Fast Response Laboratory and Factory
60 mW DFB Laser Diode
Fiber Lasers up to 2W
Aperture: 25 mm
Focal Distance: 50-100 mm
Spot Size: 100-200 μm
Diode Laser at 650 nm
50 Ohm source
100/220 V, 50/60 Hz
Provided by internal piezo mirror
325 x 250 x 100 (L x W x H, mm)
Compatible with 19-inch rack mount cabinets
Case three: Laser-Ultrasonic Systems
Fig.4-5 Two example Laser-Ultrasonic Systems: iPLUS™ II and iPLUS™ III
Ultrasonics

Target application: Ultrasonic inspection of polymer-based composite materials

Ultrasonic configuration: Pulse-echo for composite laminates

Single-sided laser-based for honeycomb sandwich structures

Signal bandwidth: up to 20 MHz
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
Number of digitizer channels: 2

Maximum digitizer sampling rate: 100 MHz

Digitizer resolution: 14 bit

Pulse repetition frequency: 400Hz(user adjustable down to single shot)

Inspection spot size: ~5 mm [0.2 in] (optional variable spot size)

Inspection step size: User selectable

Area inspection rate: 5.8m2/hr [64 ft2/hr] with 2-mm [0.08 in] steps (geometry
invariant)

Amplification dynamic range: 80 dB
Configurations


iPLUS™ II (Patent Pending)
o
Target applications: Composite parts on transportation tools, on inspection
table, or on the floor. Exterior of fuselages.
o
Footprint: 2 m X 5 m [6 ft X 16 ft] + travel length (plus electronic racks and
chillers)
o
Floor working envelope: 3 m[10 ft] X travel length
o
Maximum part height: > 5 m[16 ft]
iPLUS™ III (Patent Pending)
o
Target applications: Same as iPLUS™ II plus interior of fuselages
o
Footprint: 2 m X 5 m [6 ft X 16 ft] + travel length (+ electronics and chiller)
o
Floor working envelope: 4 m[13 ft] X travel length
o
Interior fuselage working envelope: > 6 m[20 ft] in length X 4 m [13 ft]
o
Maximum part height: > 6 m [20 ft]
User Interface

Data analysis: A, B, C-scans with large variety of analysis tools

Manual robot and laser control: Handheld remote with barcode scanner
Robotics

Robot type: 6-Axis articulated industrial robot

Linear rail travel: From 0.5 to 30 m [2 to 100 ft]

Scanning System

Scanner: 2D galvanometer with digital driver
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
Scanner positioning: 7th axis with 360°rotation, mounted in-line with robot 6th-axis

Nominal scanner-to-part distance: 1800 mm [6 ft]

Depth of field: ±250mm [± 1 ft] from nominal distance (optional range measurement)

Scan area maximum dimensions: 1600mm x 1600 mm [5 ft X 5 ft]

Inspection step index: User selectable

Maximum angle of incidence: 45°from surface normal

Laser alignment: Automatic
Generation Laser

Laser type: Industrial pulsed TEA CO2 laser

Laser wavelength: 10.6 µm

Pulse duration: < 100 ns (FWHM)

Pulse energy: > 180mJ at part surface

Maximum pulse repetition rate: 400Hz

Maintenance cycle: > 1 Billion shots (approximately 1 year)
Detection System

Interferometer type: Confocal dual-cavity Fabry-Perot(Patent Pending)

Interferometer bandwidth: 0.5 MHz to 20 MHz(optional absolute response
calibration)

Stabilization: Automatic. Optical stabilization circuit independent from sample light,
ensuring 100% stabilization (patent pending).
Detection Laser

Laser type: Industrial fiber laser amplifier seeded by a non-planar ring oscillator

Laser wavelength: 1.064 µm

Pulse duration: 300 µs (flat within ± 1 dB over 50 µs)

Maximum pulse peak power: 500 W (optional 800 W version)

Maximum pulse repetition rate: > 1 kHz

Laser power control: Automatic, 1% to 100% on a shot-by-shot basis

Maintenance cycle: None
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Safety Systems and Facility Requirements

Inspection area requirement: Laser safe as per local regulations

Power requirement: 380 V, 50Hz, 100 A or 460 V, 60Hz, 100 A

Water: None

Compressed air: 7 bar [100 psi]
Maintenance and Diagnostics

Maintenance cycle: Biannualsystem check (1/2 day) and yearly CO2 laser
refurbishment (2 days)

Laser power monitoring: Automatic

Laser alignment monitoring: Automatic

System performance data logging: Automatic
Options

Range measurement system

Generation spot size control

800 W detection laser
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5
5.1
Eddy-Current Testing
Introduction
Eddy-current testing uses electromagnetic induction to detect flaws in conductive materials.
In a standard eddy current testing a circular coil carrying current is placed in proximity to the
test specimen (which must be electrically conductive).The alternating current in the coil
generates changing magnetic field which interacts with test specimen and generates eddy
current. Variations in the phase and magnitude of these eddy currents can be monitored
using a second 'receiver' coil, or by measuring changes to the current flowing in the primary
'excitation' coil. Variations in the electrical conductivity or magnetic permeability of the test
object, or the presence of any flaws, will cause a change in eddy current and a
corresponding change in the phase and amplitude of the measured current. This is the
basis of standard (flat coil) eddy current inspection, the most widely used eddy current
technique (Wikipedia 2013).
Fig.5-1 the scheme of measuring system placement on the vehicle for the track
measurement (Yu et al. 2004).
Applications
The Eddy-Current Testing (ECT) is mainly used to detect damages caused by rolling
contact fatigue of rails.
Advantages (TWI 2013)

Able to detect defects of 0.5mm in length under favourable conditions.

The ability to detect defects in multi-layer structures (up to about 14 layers),
without interference from the planar interfaces.
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
Able to detect defects through non-conductive surface coatings in excess of
5mm thickness.

Dedicated conductivity measurement instruments operate using eddy currents.

Relatively uniform parts can be inspected quickly and reliably using automated
or semi-automated equipment, e.g. wheels, boiler tubes and aero-engine disks.

Only major soils and loose or uneven surface coatings need to be removed,
reducing preparation time.

Portable test equipment is very small and light, some of the latest equipment
being as small as a video cassette box and weighing less than 2kg.
Limitations:

Very susceptible to magnetic permeability changes. Small changes in
permeability have a pronounced effect on the eddy currents, especially in
ferromagnetic materials. This makes testing of welds and other ferromagnetic
materials difficult but, with modern digital flaw detectors and probe design, not
impossible.

Only conductive materials can be tested. The material must be able to support a
flow of electrical current. This makes testing of fibre reinforced plastics
unfeasible. The depth of penetration into the material is limited by the materials'
conductivity.

Flaws that lie parallel to the probe may be undetectable. The flow of eddy
currents is always parallel to the surface. If a planar defect does not cross or
interfere with the current then the defect will not be detected.

The surface of the material must be accessible. Large area scanning can be
accomplished, but needs the aid of some type of area scanning device, usually
supported by a computer, both of which are not inexpensive. The more complex
the geometry becomes, the more difficult it is to differentiate defect signals from
geometry effect signals.

Signal interpretation required. Due to the many factors which affect eddy
currents, careful interpretation of signals is needed to distinguish between
relevant and non-relevant indications.

No permanent record (unless automated). Normally the only permanent record
will be a paper print out or computer file when using automated systems.
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5.2
Hardware and software
Fig.5-2 General scheme of PKRN-01 system (Yu et al. 2004).
5.2.1
Case one: the SPZ1 inspection train
Fig.5-3 Probe arrangement for rail inspection (HECKEL et al. 2009)
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With the exception of the 4 MHz 0° normal probe used for the rail head, which is operated
in transmitter receive mode, all ultrasonic angle beam probes are operated in pulse-echo
mode. All probes are GE type in standard housing, with fix mounted wiring and there are
four HC-10 type eddy current sensors which are aligned based on the rail head shape. The
sensors are located in the area where rolling contact occurs and can access a surface
range of ~25 mm in the gauge corner of the rail.
The overall system consists of four modular multichannel ultrasound devices, two
multichannel eddy current devices, eight dual core personal computers for real time signal
processing and system control, two 32 channel real time controllers, one GPS positioning
system and two FPGA based custom designed signal processing hardware boards. The
measurement system rack is displayed in Fig.6-4.
Fig.5-4 Rail inspection hardware system
For ultrasonic inspection, four slide-type holders, which are equipped with direction
dependent and speed controlled couplant supply, encase two to three ultrasonic probes.
These probes are each fixed in position via springs with calibrated tension, to be adjusted
with a special calibration device to a gap of 0.2 mm between the rail head and the probe
show. The aim of this is to minimise abrasions and optimise coupling.
A small water reservoir and bleeder is provided for each probe and a lockable tilting
mechanism enables easy access when charging the holders with probes. The four sensors
are positioned over each rail with a trolley-type holder and are mounted on a guidance
device carried by the measuring trolley. The probes are mounted on a modular mechanism
to allow the measurement tracks to be individually positioned.
A special calibration device is used to fix the sensors 1mm from the surface of a new profile
UIC 60 rail, though the distance of the sensors can be varied according to how worn the rail
surface is. All measurement data are delivered digitally via network connection and
synchronisation of all devices is controlled by 80+ hardware signals.
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The newly developed MODUS03 modular inspection system is used for ultrasound data
acquisition. Two MODUS03 complete with five high resolution ultrasound boards each
connected to ten probes are used for each rail. For each channel, at a repetition frequency
of 4650 Hz (independent of operation speed), 14-bit AScan data, four fixed hardware gates
and four interactive controlled gates are recorded continuously. The measurement data are
combined in real time with information such as time stamps, kilometre markers and GPS
information.
To collect eddy current data, two 4 channel PL300 series eddy current measurement
devices are applied. Like ultrasound data acquisition, measurement data are combined in
real time and the lateral resolution for eddy current data is 1 mm, irrespective of operation
speed.
The SPZ1 inspection train of Deutsche Bahn AG uses a state of the art ultrasound and
eddy current inspection system which consists of ten ultrasonic probes and four eddy
current sensors on each rail.
By combination of the ultrasonic inspection results with these from the simultaneously
performed eddy current inspection synergetic effects arise.
These can be excellently used to overcome problematic defect classification based on the
results of only one testing method.
The measurement software contains online software detection for drill holes and thermite
welds. This enables the operator to view live pictures from indications whilst measuring,
and the performance of each sensor can be monitored. By combining the performance
information with real time controller boards, the operator can optimise testing parameters
during measurement online. Parameter changes made by the operator are recorded and
the offsets from the actual parameter set to these from the calibration are known for all
measured positions.
Table 5-1 Detectability of Eddy-Current Inspection Technique (Thomas et al. 2006)
Category
Head Checking
BelGroSpi' s
Squats
Indentures
Wheelburns
Short/Long pitch corrugation
Grinding marks
Welds
Rail joints
Detectability
very good
good
good
very good
very good
good
very good
good
very good
Statement
Quantity, Location, Depth
Quantity, Location
Quantity, Location
Quantity, Location, Period
Location, Extent
Location, Period
Quantity, Place, Period
Location, Kind, Lack of fusion
Location, Kind
From the point of present inspection experience it can be concluded, that improvements by
using a combination of ultrasound and eddy current are possible in the following cases:
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SMARTRAILSmart maintenance analysis and remediation of transport infrastructure
Welds can be detected and it can be decided on whether it is a thermite-weld or a flash butt
weld. In addition, statements about possible surface-breaking damages such as cracks or
spalling can be made.
Rail joints can be detected free of doubt. It is possible to determine whether indications
relate to a simple or reinforced rail joint. In addition, degradations of insulated rail joints can
be identified.
If a fishing table is indicated by ultrasonic inspection, with the help of eddy current
inspection it can be decided whether the rail joint is a lap joint or a welded joint. If it is a
welded joint, by means of the eddy current signal statements about additional surface
breaking damages can be made.
A loss or an insufficient coupling of the ultrasonic probes appears occasionally and can not
be avoided completely. In many cases the reason for loss of coupling can be determined by
the help of eddy-current inspection, for instance corrugation, wheelburns, head checking
and spalling.
Head checking. In general standard configuration ultrasonic probes cannot detect head
checking. The eddy current inspection system was optimized on the detection and
quantification of head checking.
Squats. Determination of squat-type damage depth is principally problematic with both
inspection techniques. However, deeper defects can be sized better by ultrasonic
inspection rather than by the eddy current technique. At the surface, squats can be
detected more sensitively by eddy current inspection. The eddy current inspection gives
additional information about the geometrical extent in the gauge corner and can detect
additional head checking.
The eddy current inspection system was originally developed for head checking detection
and is able to quantify damages. Only events at certain local positions are available for later
analysis as indications are only recorded by the ultrasonic inspection system when a predefined mask is exceeded. Complete raw data are recorded which may be analysed later
on in order to facilitate manipulation of recorded data with changed settings.
Eddy current inspection systems generate a much higher number of indications than
ultrasonic inspection. As a result, the recorded whole data sets of eddy current signals are
generally evaluated using computers as opposed to visually.
Nevertheless, measuring signals in form of amplitude versus displacement of every sensor
can be displayed at any location by the inspection system on requirement. Because both
inspection systems receive their local information from the same displacement transducer,
every ultrasonic indication can be supplied with an additional synchronous eddy current
indication from stored data. Conversely this is not possible. Thereby it is obvious that eddy
current signals are a huge evaluation help for ultrasonic indications.
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Fig.5-5 Ultrasonic standard equipment of inspection vehicles (Thomas et al. 2006)
Fig.5-6 Eddy current sensors of inspection vehicles (Thomas et al. 2006)
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5.2.2
Case two: ELOTEST PL300
Technical Data of ELOTEST PL300 from Rohmann GmbH (2004) as another case are
described here. ELOTEST PL300 – A compact and high-performance eddy current test
instrument is mainly for applications with up to 4 channels featuring imaging.
Fig. 5-7 ELOTEST PL300 from Rohmann GmbH (2004)
Eddy Current Features

Test frequency 10 Hz – 10 MHz

Transmitting driver: 20 Vss, max. 400 mA, short-circuit- proof

Preamplification 6 – 40 dB (6 dB to 52 dB below 100 kHz) in 0.5-dB steps

Gain 0 dB to 60 dB in 0.5-dB steps

Y-axis spread 0 dB to 30 dB in 1-dB steps

Phasing 0° - 359.5° in 0.5° steps

Signal filter LP/HP: 1.8 Hz to 10 kHz in 40 steps separately adjustable; bandpass with variable bandwidth; HP may be disabled.
Probe Connection

All probe types may be used

Probe connection via 15-pin D-Sub-connector

Configurations of the connection:
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-
all channels may be freely combined on up to 2 probe connectors via an
analog multiplexer (multi-frequency operation of up to 2 probes)
-
One probe connector exclusively per test channel (up to 4 probes for the
ELOTEST PL340)
Universal Scanner Interface
Dual multifunction connector (2 x 44-pin HD-Sub-connector) for rotary pulse encoder,
analog encoder, analog output and TTL I/O featuring the following counter modes:
-
Adjustable timebase
-
Up-/down-counter with simple pulse, double pulse and quadruple pulse
-
Analog input for linear encoders
Additional Interfaces

Ethernet port (10/100 Mbit/s; RJ45, 100 BaseT)

USB-port (type 1) for keyboard and mouse

VGA-port for an external monitor

Parallel interface for the printer (Centronix)
Housing

19”, 2-HU slide-in housing, IP30

All connections on the backside

Forced ventilation with a fan
Dimensions

Width approx. 428 mm (16.85”)

Depth approx. 345 mm [13.58”] (incl. handles 385 mm [15.16”])

Height approx. 88 mm (3.46”)
Weight
Weight without external power pack 5.3 kg (11.68 lbs)
Power Supply
Wide-range power pack, internal

Input 120 – 240 V/AC; 50 – 60 HZ, 70 A

Max. 3.15 A; 100 V: 0.7 A, 240 V: 0.3 A
Instrument Versions

ELOTEST PL310: 1-channel test instrument
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
ELOTEST PL320: 2-channel version; with two independent test channels may be
configured as master-/slave channel

ELOTEST PL330: 3-channel version; with three independent test channels may be
configured as master-/slave channel

ELOTEST PL340: 4-channel version; with four independent test channels may be
configured as master-/slave channel
Operating Features

19”-plug-in module without operating elements of its own

Operation via directly connectable display and keyboard or Ethernet-interface
(TCP/IP/protocol) and a suitable software

Win-Client operating software with parameter handling, signal display and recording
for Windows PC-systems included in the scope of delivery

Description of the interface for customized software available upon request
Probe Array Multiplex

Max. 32 probes
Conductivity Measurement

Measurement in % IACS or MS/m between 1 % IACS and 110 % IACS;

Test frequency 60 kHz, 120 kHz, 240 kHz or 480 kHz respectively

Calibration to 2 individually adjustable calibration marks
Layer-Thickness Measurement

Measures non-conductive layers on conductive non-ferritic materials

Measuring range up to 1000 m or 40 mils
5.2.3
Case three: Modular ultrasonic testing system
Technical data for Modular ultrasonic testing system (Büro für Technische Diagnostik
2013):
Analog-to-digital converter:

Converter Type: Flash

Sampling Rate: 100 MSPS

Quantisierungstiefe: 14 bit

Maximum input voltage: 2.2 VSS
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Digital-to-analog converter:

Output: Voltage

Resolution: 8 bits

Settling time: <1 μs

TGC dynamics: 40 dB in 1 dB steps

TGC points: 1000
Transmitter stages

Number of channels: 16

Pulse shape: rectangle

Minimum pulse width: 50 ns

Maximum pulse width: 500 ns

Variation in steps of 10 ns

Pulse rise time: 3 ns

Pulse fall time: 8 ns

Maximum pulse amplitude: 330 VS at 110 Ω
Receiver levels

Multiplexer input channels: 16

Multiplexer: 16:1

Amplifier type: linear

Upper cut-off frequency: 11 MHz (-3 dB)

Lower cut-off frequency: 0.7 MHz (-3 dB)

Maximum Gain: 80 dB

Minimum gain: - 4dB

Gain position: 0 - 84 dB

Amplification steps of 1 dB

Gain deviation: <1 dB

Input dynamic range: 100 dB (regulated)

Maximum input level: 3.5 VPP at vmin

Minimum input level: 50 μVSS with vmax

Output voltage: 2.2 VSS
Software Architecture
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It uses Microsoft Windows 98 as the operating system, and the test data can be exported
for further analysis.
5.2.4
Case four: Modular ultrasonic testing system
Fig.5-8 GE (2013) Standard Eddy Current Probes
GE Inspection Technologies manufactures various standard eddy current probes. Its
standard probe line consists of probes used to inspect surface, sub-surface, fastener holes,
aircraft wheels, and welds and conductivity probes for measuring non-ferrous materials.
Surface inspection shielded eddy current probes are used to inspect for surface breaking
defects.
Table 5-2 Straight - Delrin Handle (Absolute) (GE 2013)
Part Number
Tip Ø
Length
Center Frequency
Material
104P4
4.45
114 mm (4.5")
200kHz
Fe/NFe
104P4F
3.30
114 mm (4.5")
200kHz
Fe/NFe
105P4
4.45
114 mm (4.5")
500kHz
Fe/NFe
105P4F
3.30
114 mm (4.5")
500kHz
Fe/NFe
106P4
3.30
114 mm (4.5")
2MHz
NFe
106P4F
2.34
114 mm (4.5")
2MHz
NFe
107P4
2.34
114 mm (4.5")
6MHz
NFe
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Table 5-3 15º Crank, 90º Tip - Delrin Handle (Absolute) (GE 2013)
Part Number
Tip Ø
*Tip Length
Length
Center
Frequency
Material
312P24
4.45
6.4 mm (0.25")
114 mm (4.5")
200kHz
Fe/NFe
313P24
4.45
6.4 mm (0.25")
114 mm (4.5")
500kHz
Fe/NFe
313P24F
3.30
6.4 mm (0.25")
114 mm (4.5")
500kHz
Fe/NFe
314P24
3.30
6.4 mm (0.25")
114 mm (4.5")
2MHz
NFe
315P24
2.34
6.4 mm (0.25")
114 mm (4.5")
6MHz
NFe
* Inside tip lengths available from 5mm (0.19”) to 25mm (0.98”) on all probes.
5.2.5
Case five: eddy current sensor probe
Fig.5-9 Dimension of eddy current sensor probe (Song et al. 2011).
An inspection system of rail flaws used in this study included a detection coil and an
excitation coil, which formed an eddy current sensor probe. The width of the railhead was
65 mm; thus, the detection coil in the sensor probe could not effectively evaluate the entire
plane of the rail top. Therefore, the position of the sensor probe was varied in five different
positions along the width. The scan speed of the sensor probe was 2.5 mm/s and the data
acquisition rate was 8 point/s (3.2 point/mm). The frequency of the exciting magnetic field
was 5 kHz.
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Fig.5-10 Position and scanning direction of eddy current sensor probe on railhead.
5.2.6
Case six: HC Series Metal Tip Sensor
The Model HC Metal Tip Sensor (Shinkawa 2013) is an eddy-current displacement vibration
converter which measures without contact the shaft vibration and thrust displacement of
compressors and pumps which require complete sensor pressure tightness and sealing.
Features

A metal tip sensor is used, thereby improving erosion resistance and increasing
mechanical strength.

Highly strong, heat and corrosion resistant alloy is used, thereby greatly improving
pressure resistance max. 13Mpa (133kgf/cm2)

The sensor block and extension cable are made of high radiation resisting materials,
γ-ray (Co-60 radiation source) 1 ×105Gy max.
Specifications

Measured range: 3mm

Frequency response: DC to 5kHz (−3dB, +1.5dB)

Caribration target: SUS431

Output: 0 to 5VDC / 0 to 3mm

SN ratio: More than 50dB at 1.2mm
Accuracy

Scale factor error: Within ±15%
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
Linearity: Within ±1.5% of F.S. (calibration accuracy in the air)

The difference between water and air: Within ±2% of F.S

Converter power supply: ±15VDC
Operating (Sensor)

Environment: air/water

Operating temperature: 0 to 150°C (32 to 302°F)

Heat resistance: 300°C max. (Electrical guarantee : 150°C max.)

Test pressure: Max. 13MPa (133kgf/cm2)

Bearing radioactive ray: γ-ray (Co-60 radiation source) 1 × 105Gy max.

Coil resistance: Active coil (between A C terminal) 19.5Ω ± 1Ω; Reference coil
(between B C terminal) 17.5Ω ± 1Ω

Insulation resistance: between cable core wire body More than 500VDC, 100MΩ

Dielectric strength: between cable core wire body 500VAC/1min. Within 0.5mA leak

Mass: 400g±50g
Operating (Extension cable)

Environment: air

Operating temperature: 0 to 150°C (32 to 302°F), Normal pressure

Relative humidity: 10 to 90% RH (noncondensing)

Bearing radioactive ray: γ-ray (Co-60 radiation source) 1 × 105Gy max.

Insulation resistance: between cable core wire body More than 500VDC, 100MW

Dielectric strength: between cable core wire body 500VAC/1min., Within 0.5mA leak

Mass: 1400g±200g
Operating (Converter)

Environment: air

Operating temperature, pressure: 0 to 65°C (32 to 149°F), Normal pressure

Relative humidity: 10 to 90% RH (noncondensing)

Insulation resistance: Power supply GND. More than 500VDC, 100MΩ

Dielectric strength: Power supply GND. 1500VAC/lmin., Within 10mA leak

Mass: 850g ± 100g
Power unit

Input signal: 0 to 5VDC × 1ch, Input impedance Approx. 10kΩ
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
Output: 0 to 5VDC × 2ch, Output impedance Approx. 100Ω

I/O convertion accuracy: Within ±2% of F.S.

Zero shift: −50 to 0% (changeable)

Power supply output: ±15VDC (max.10.1A)

Power supply: 100VAC ±10% or 115VAC±10%, 50/60Hz±5%

Operating temperature: 0 to 40°C (32 to 104°F)

Relative humidity: 10 to 90% RH (noncondensing)

Insulation resistance: Power supply GND. More than 500VDC, 100MΩ

Dielectric strength: Power supply GND. 250VAC/1min., Within 10mA leak

Power consumption: 12VA

Mass: 1100g±100g

Accessory: Fuse (MF-51 NH 250V 0.5A)
Fig.5-11 Power Unit Outline Drawing (dimension: mm) (Shinkawa 2013)
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Fig.5-12 Converter Outline Drawing(dimension: mm) (Shinkawa 2013)
Fig.5-13 Sensor Outline Drawing (dimension: mm) (Shinkawa 2013)
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Fig.5-14 Extension Cable Outline Drawing (dimension: mm) (Shinkawa 2013)
5.2.7
Case six: GE Hocking Phasec 3 Eddy Current Meter
Fig.5-15 GE Hocking Phasec 3 Eddy Current Meter (Ashtead Technology 2013)
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SMARTRAILSmart maintenance analysis and remediation of transport infrastructure
The Phasec 3 offers full phase plane functionality in an ultra-compact package, which can
easily fit into a toolbox or a briefcase. Using the GE WeldScan range of probes, the Phasec
3 Series offers an advanced system for checking the integrity of welds on steel structures
such as bridges, ships, oil rigs and steel framed buildings. Cracks can be detected through
surface coating materials such as paint and aluminium, so minimal time and resources are
needed for preparation. The WeldScan range of probes can be used on ferrous, stainless
steel (magnetic and non-magnetic) and aluminium materials. The technique has been
written into British and European Standard BS EN 1711:2000.
Key Features of GE Hocking Phasec 3 Eddy Current Meter (Ashtead Technology 2013)

Advanced colour LCD allows easy viewing in all ambient light situations.

Compatible with all commonly used eddy current probes.

Display can be phase plane, Y/t or bar graph.

Easy computer connectivity with the integrated USB connection and fast data
exchange using supervisor software.

Increased instrument memory can store up to 200 set-ups and 200 traces.

Light weight and portable with up to six hours battery life.

Signal colour coding enhances signal interpretation and trace recall mode allows
easy comparison.
Table 5-4 Technical Specification of GE Hocking Phasec 3 Eddy Current Meter (Ashtead
Technology 2013)
GAIN
Overall
Input
Drive
Max X/Y Ratio
PHASE
Range
Auto lift off
FILTERS
Normal High Pass
Normal Low Pass
BALANCE LOAD
ALARMS
Box
Sector
OPERATING MODES
DISPLAY
Type
Viewable Area
Resolution
-8 - +96 dB, 0.1 steps
0/14 dB
-8,0, +8 dB
-74.0 - 74.0 dB
0 - 359.9°, 0.1 steps
Yes
Dc-ultra-1 - 1200 Hz, 1675 steps
3 - 1500 Hz, 2440 steps
Automatic/Manual
9 modes
2 modes
Single Frequency, Conductivity, Coating Thickness
Colour TFT
117.2 x 88.4mm
320 x 240 pixels
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Colour schemes
Display Modes/Trace
views
Graticules
Features
INTERNAL DATA
STORAGE
Stored setups up to
Stored traces up to
Record Replay
PROBE
CONNECTION
OUTPUTS
8
05/01/2011
None, Polar, Grid 1, Grid 2
Trace Recall with Colour Enhancement of Overlapped
Live Trace; Digital Spot Position Readout
200
200
60s
12 way Lemo
USB, Digital volt free alarm, VGA
2 channels, configurable as X1, Y1, X2, Y2, X mix or Y
ANALOGUE OUTPUT mix
English, French, German, Spanish, Portuguese, Chinese,
LANGUAGES
Japanese
PHYSICAL
Operating
Temperature
0-40°C
IP Rating
54
Display Modes
Spot, Time base, Waterfall and Bargraph)
Table 5-5 Dimensions of GE Hocking Phasec 3 Eddy Current Meter (Ashtead Technology
2013)
Title (mm)
192 x 139 x
57mm
(inch)
7.6 x 5.5" x
2.2""
(c) The SMARTRAIL Consortium 2012
(kg)
1.1kg (including
battery)
(lbs)
2.4lbs (including
battery)
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6
Magnetic encoders
6.1
Introduction
Magnetic encoders testing is based on the magnetic and inductive sensing principles using
hall-effect magneto-resistance and Eddy current sensors with metal targets and employ the
very latest sensor technology, circuitry and construction techniques. They have proved to
be reliant in thousands of railway projects during the last decades.
Applications
Identification of rail defects, extent in rigid pavements, bridge components, and tunnels.
Advantages
•
Withstand contaminants such as dirt, dust, moisture, water and temperature
changes
•
Greater reliability and durability
•
Integrated electronics
•
Compact size
Limitations
•
Subject to radio and magnetic interference
•
Low Resolutions
•
Sensitivity to temperature effects Less accurate compared to some optical encoders
Hardware
6.2
Hardware and software
The hardware for corrosion sensing based on magnetoresistive sensor technology is not
yet developed for field use.
6.2.1
Case one: Walking Stick from Sperry Rail
Sperry Rail’s ‘Walking Stick’ uses non-contact magnetic rotary encoders. The RE22 is a
compact, high-speed rotary magnetic magnetic encoder by Renishaw. A magnet is
mounted to the shaft within the compact 22 mm diameter encoder body and the rotation of
this magnet is sensed by a custom encoder chip within the body. The encoder chip
processes the signals received to provide resolutions to 13 bit (8192 positions per
revolution) with operational speeds to 20,000 rpm and output signals provided in industry
standard absolute, incremental or analogue formats.
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Fig.6-1 Sperry Rail’s ‘Walking Stick’ non-contact magnetic rotary encoders contribute to rail
track safety (Jemec and Grum 2010).
Performance characteristics: resolution, power consumption, weight, size and I/O
configurations, the encoders also help record auditable data.
Cracks usually form at an angle of 20 degrees against the direction of normal travel, but a
bi- directional line can grow cracks in both directions.
6.2.2
Case two: rotary magnetic encoders RE22
RLS (2009) rotary magnetic encoders RE22 are used in Sperry Rail ‘Walking Stick’. The
technical data for the RE22 are below.
Features
•
Excellent immunity to IP68
•
High speed operation to 20,000 rpm
•
Compact - 22 mm diameter body
•
Absolute - to 13 bit (8192 counts per revolution)
•
Industry standard absolute, incremental and analogue output
formats
•
Accuracy to ±0.3°
•
Power supply 5 V
•
Simple integration
•
RoHS compliant (lead free)
(c) The SMARTRAIL Consortium 2012
Fig.6-2 RLS (2009)
rotary magnetic
encoders RE22
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Table 6-1 Specification (RLS 2009)
Diameter
Weight
Length
Body style
Resolution
Outputs available
Maximum speed
Accuracy
Power supply
Environmental
sealing
Cable exit type
Shaft diameter
Connector options
Operating
temperature
Housing material
22 mm
With 1 m cable (no connector) IP53 axial cable 68 g, side cable 60 g,
IP64/68 axial cable 73 g
IP68/64 - 43 mm including shaft, IP53 - 36 mm including shaft
Bearing/shaft style
To 13 bit (8192 counts per rev)
Industry standard absolute, incremental and analogue output formats
To 20,000 rpm
To ±0.3°
5 V ± 5%
IP53, IP64 or IP68
Axial or Radial (IP53 only)
4 mm
Flying lead, 9 way 'D' type connector and 15 way 'D' type (parallel
format only)
-25 °C to +85 °C
Encoder body - aluminium
Fig.6-3 RE22 installation drawing (Dimensions and tolerances in mm) (RLS 2009)
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Table 6-2 Operating and electrical specifications(RLS 2009)
Humidity
(for IP64 version)
Acceleration
Shock (nonoperating)
Vibration (operating)
EMV compliance
Cable
Mass
Environmental
sealing
NOTE:
Storage 95% maximum relative humidity (non-condensing) (IEC
61010-1)
Operating 80% maximum relative humidity (non-condensing) (IEC
61010-1)
Operating 500 m/s2 BS EN 60068-2-7:1993 (IEC 68-2-7:1983)
1000 m/s2, 6 ms, 1/2 sine BS EN 60068-2-27:1993 (IEC 68-227:1987)
100 m/s2 max at 55 to 2000 Hz BS EN 60068-2-6:1996 (IEC 68-26:1995)
BS EN 61326
Outside diameter 5 mm
Encoder unit 1 m cable (no connector) IP53 axial cable 68 g, side
cable 60 g. IP64/IP68 axial cable 73 g.
IP53 (IP64/IP68 optional) BS EN 60529:1992
IP68 version must be operated immersed in fluid
Table 6-3 Expected bearing life ratings in hours(RLS 2009)
Speed
(rpm)
500
1,000
2,000
5,000
10,000
15,000
20,000
Rad. load
5N
205,401
102,700
51,350
20,540
10,270
6,847
5,135
Rad. load
10 N
98,455
49,227
24,613
9,845
4,923
3,282
2,461
Rad. load
15 N
54,569
27,285
13,642
5,457
2,728
1,819
1,364
Rad. load
20 N
33,333
16,667
8,333
3,333
1,667
1,111
833
Table 6-4 RE22S – Absolute binary synchro-serial interface (SSI) (RLS 2009)
Output code
Power supply
Power consumption
Repeatability
Data outputs
Data inputs
Max. cable length
Connector options
Temperature
(c) The SMARTRAIL Consortium 2012
Natural binary
Vdd = 5 V ± 5%
23 mA for 9 bit resolution; 35 mA for all other resolutions
≤ 0.07°
Serial data (RS422A)
Clock (RS422A)
100 m (at 1 MHz)
9 pin ‘D’ type plug (standard); Flying lead
Operating: -25 °C to +85 °C; Storage: -25 °C to +125 °C
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Table 6-5 RE22S operation data (RLS 2009)
Resolution options
(positions per rev)
320, 400, 500
512
800, 1,000, 1,024
1,600, 2,000, 2,048
4,096
8,192
Maximum speed
(rpm)
20,000
20,000
20,000
10,000
5,000
2,500
Accuracy*
Hysteresis
±0.5°
±0.5°
±0.3°
±0.3°
±0.3°
±0.3°
0.18°
0.45°
0.18°
0.18°
0.18°
0.18°
* Worst case within operational parameters including magnet position and temperature.
Clock ≤ 900 kHz 16 μs ≤ tm ≤ 22 μs (for 9 bit resolution)
Clock ≤ 4 MHz 12.5 μs ≤ tm ≤ 20.5 μs (for all other resolutions)
Fig.6-4 RE22S Timing diagram (RLS 2009)
Fig.6-5 Recommended signal termination for RE22S (For data output lines only) (RLS
2009)
The software depends on the data acquisition system used. It can be LabView, Matlab, or
any other common data acquisition software.
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7
Alternating Current Field Measurement (ACFM)
7.1
Introduction
Alternating Current Field Measurement (ACFM) is an electromagnetic technique for the
detection and sizing of surface breaking cracks. A sensor probe is placed on the surface to
be inspected and an alternating current is induced into the surface. When no defects are
present the alternating current produces a uniform magnetic field above the surface. Any
defect present will perturb the current, forcing it to flow around and underneath the defect;
this causes the magnetic field to become non-uniform and sensors in the ACFM probe
measure these field variations.
Fig.7-1 Definition of field directions and co-ordinate system used in ACFM (Papaelias et al.
2010)
Applications
It is used to detect Rolling Contact Fatigue (RCF) damage of rails at high speeds even
when measurable lift-off is involved. Other usages in:
•
Structural weld inspection
•
Offshore cranes
•
Storage Tanks floor and roof ‘lap’ joints
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•
Storage Tank annular welds internal and external
•
Vessel nozzles
Advantages
It works through several millimetres of coatings. This means that paint and other protective
coatings do not have to be removed and then reapplied.
•
No need to remove paint or thin coatings
•
Detects and sizes both crack length and depth
•
Offline analysis of data
•
Provides a permanent record of indications
•
Ongoing monitoring capability
•
Provides an immediate evaluation of the weld area
•
Quick and efficient method of inspection
•
High temperature capability
•
Works equally well on plain material or welds, ferritic or non-ferritic.
•
Has almost no consumable costs
•
Requires little if any surface preparation.
•
Does not contaminate sterile environments.
•
Very quick and efficient by utilizing a 2” wide array probe.
•
Indications are sized for both length and depth in real time.
•
Provides a permanent record of inspection that can be reviewed and audited for
maximum accountability and repeatability.
•
Superficial surface indications can be disregarded through Signal Interpretation.
Limitations
•
Not recommended for short sections or small items
•
Locations of weld repairs and grinding can cause spurious indications
•
Crack length needs to be longer than 5-10mm
•
Multiple defects reduce the ability to measure the depth of crack
•
MPI may be more sensitive for shallow defects (<0.5mm deep)
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7.2
7.2.1
Hardware and Software
Case one: TSC U31
Fig.7-2 TSC U31 Underwater ACFM System (Ashtead Technology 2013)
Key Features of TSC U31 (Ashtead Technology 2013)
•
Rapid scanning using a hand-held probe.
•
Reliable crack detection and sizing (length and depth).
•
Reduced cleaning requirements with no need to clean to bare metal.
•
Capable of inspecting corroded surfaces, or through non-conducting coatings
several millimetres thick.
•
Windows software for ease of operation and compatibility with other Windows
applications.
•
Full data storage for back-up, off-line view and audit purposes.
•
Access to a wide range of geometries using TSC′s new range of active subsea
probes.
•
Probes with embedded serial numbers to simplify operation and reduce likelihood of
operator error.
•
Capable of operating at water depths up to 300m.
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Table 7-1 Technical Specifications of TSC U31 (Ashtead Technology 2013)
Optional Probes
Optional Probes
Probe Cable Length
Serial Communications
Cable
Operating Temperature
Maximum Operating
Depth
Power Requirements
Optional Array Support
TSC U31 Weld Probe, U31 Weld Probe TA 312, U31
Mini Pencil 336, U31 Micro Pencil RA 354, U31 Mircro
Probe, 'Pick and Place' probe.
5 metres standard, up to 50m by special request.
5 metres as standard up to 30 metres if required.
-20° + 40°C
300m as standard, can be extended to 2000m for ROV
deployment
110v AC. 200mA
16 channels (i.e. 8 sensor pairs) plus position encoder
Table 7-2 Dimensions of TSC U31 (Ashtead Technology 2013)
Title
Sub Sea Unit (D x L)
Weight in air
Weight in water
7.2.2
(mm)
142mm x 260mm
(inch)
5.6 x 10.2""
(kg)
(lbs)
7.6kg
4.3kg
16.8 lbs
9.5 lbs
Case two: TSC U9b ACFM Unit
Fig.7-3 TSC U9b ACFM Unit (Ashtead Technology 2013)
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The ACFM Crack Microgauge Model U9b represents a significant advance in inspection
technology. It is capable of both ac potential drop (ACPD) and ac field measurement
(ACFM) techniques. Alternating current field measurement technique and advanced
software allows for reliable crack detection and crack depth measurement, as well as
interpretation of inspection data with low chances of false calls.
The ACFM Crack Microgauge Model U9b represents a significant advance in inspection
technology and provides the capability of both ac potential drop (ACPD) and ac field
measurement (ACFM) techniques. The alternating current field measurement technique
enables reliable crack detection and crack depth measurement on a wide range of
components and structural geometries. Advanced software aids the operator in the
interpretation of the inspection data to provide reliable crack detection with low likelihood of
false calls.
Key Features of TSC U9b (Ashtead Technology 2013)
•
Rapid scanning using a hand-held probe
•
Reliable crack detection and crack sizing without need for calibration, i.e. Crack
LENGTH and Crack DEPTH
•
Multi frequency option - 200Hz, 1kHz, 5kHz
Table 7-3 Technical Specification of TSC U9b (Ashtead Technology 2013)
Optional Mains Pack
Probe cable lengths
Serial Communications Cable length
Operating Temperature
110/240V 3Kg
Up to 20m
up to 25m
0° - 35°C
Table 7-4 Dimensions of TSC U9b (Ashtead Technology 2013)
Title
Weight
(mm)
(c) The SMARTRAIL Consortium 2012
(inch)
(kg)
15 kg
(lbs)
33 lbs
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7.2.3
Case three: TSC Amigo ACFM Unit
Fig.7-4 TSC Amigo ACFM Unit (Ashtead Technology 2013)
The Amigo represents a significant advance in ACFM topside inspection technology. The
unit is smaller, lighter and has a longer battery life and support for array probes, with at
least 5 hours of operation time on a fully charged battery. In addition, the hand held probes
allow for rapid scanning and the unit is able to inspect through several millimetres thick nonconducting coatings or thin metallic coatings. The Windows-based software ensures that
the Amigo is compatible with other Windows applications and rents with Amigo Processor,
pencil probe, weld probe, probe extension cable, test plate associated cable and software.
Optional rental items: Laptop, High Frequency Unit.
Key Features of TSC Amigo ACFM Unit (Ashtead Technology 2013)
•
Rapid scanning using a hand-held probe.
•
Reliable crack detection and sizing (length and depth).
•
Dual frequency option: 5kHz
•
Rugged site unit, IP54 rated.
•
Around 10 hour operation on one fully-charged battery pack, and easy exchange of
battery packs in the field.
•
Reduced cleaning requirements with no need to clean to bare metal.
•
Capable of inspection through thin metallic coatings, or through non-conducting
coatings up to 10mm thick.
•
Windows software for ease of operation and compatibility with other Windows
applications.
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•
Full data storage for back-up, off-line view and audit purposes.
•
Access to a wide range of geometries using TSC′s new range of active topside
probes.
•
Buttons for RUN / STOP and MARKERS on instrument and larger probes to allow
one-man operation in difficult access areas.
•
Intelligent probes to simplify operation.
Table 7-5 Technical Specification of TSC Amigo ACFM Unit (Ashtead Technology 2013)
Probe Cable Length
Serial Communications Cable Length
Operating Temperature
Environment Protection
Array Support
5m (16.4ft) standard, up to 50m (164ft) by
special request.
Up to 30 metres (98ft)
-20° to 40°C
-4° to +104°F
IP54 rated
16 channels plus position encoder
Table 7-6 Dimensions of TSC Amigo ACFM Unit (Ashtead Technology 2013)
Title
7.2.4
(mm)
206 x 292 x 127mm
(inch)
8.1 x 11.5" x 4.9""
(kg)
4.5 kg
(lbs)
9.9 lbs
Case four: TSC’s ACFM Walking Stick
The ACFM Walking Stick instrument provides a thorough analysis of surface breaking railhead defects. Designed by TSC to offer a comprehensive and reliable solution for the
analysis of defects, this technology has a range of applications throughout the rail industry.
Fig.7-5 TSC’s ACFM Walking Stick (TSC Inspection Systems 2013)
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Walking Stick Applications (TSC Inspection Systems 2013)
ACFM, originally developed for detecting and sizing surface-breaking defects with minimal
surface preparation within the oil and gas industry, is now used in a wide range of industries
for magnetic particle or dye penetrant inspection. For example, in the rail industry, ACFM is
used to complement ultrasonic inspection by inspecting:
•
Axles – surface breaking defects, particularly on solid axles or in difficult access
regions such as under earth-return brushes.
•
Wheels – transverse cracking on wheel rims and flanges.
•
Bogies – inspection without removing paint, and on internal welds through access
holes.
•
Rails – head checking where inclined cracks are clustered together.
All applications can take advantage of automated interpretation for both detection and
depth sizing, and storage of all data for off-line review and auditing.
Walking Stick Features
•
Inspects the whole rail head surface in one pass.
•
Audible warning of defects.
•
Deepest defect per yard automatically reported and sized.
•
Longitudinal position in miles and yards on rail recorded.
•
Battery life in excess of 5 hours continuous use (easy swap).
•
Automated export of inspection summary in Microsoft® Excel format.
•
Import and archive of all inspection data on an office-based system.
Benefits
Following rigorous site trials by an independent UK rail technology company, the system
has been found to be both reliable and capable for identifying and classifying both small
and large Rolling Contact Fatigue (RCF) cracks. This efficiently allows:
•
Maintenance strategy planning based on rail categorisation
•
Defect monitoring following maintenance/grinding
Comparison
In conventional ultrasonic inspection techniques, large numbers of defects may render a rail
un-testable. In contrast, the deeper the crack, the larger the response yielded in ACFM. Its
other advantages include:
•
Use as a primary inspection tool on plain line inspection to determine the presence
of surface-breaking rail head defects.
•
Categorising rail for assessing the maintenance strategy.
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•
Inspection before grinding to assess the amount of material removal.
•
Post-grinding inspection to confirm the removal of defects.
•
Monitoring crack growth/re-growth to assess the effectiveness of maintenance
strategies and machine grinding frequencies.
Table 7-7 Specifications of TSC’s ACFM Walking Stick (TSC Inspection Systems 2013)
Unit Weight
21kg
Unit Size
700mm x 300mm x 1000mm
Scan Rate
15 m/min
Typical Operating Speed
1.5 – 2 mph (2 – 3 km/h)
Probe Support
16 channels plus position encoder
Power Requirements
Integral 12V battery supply, recharged by domestic 110V or
240V AC 40 / 50 Hz supply
Operating Temperature
-20º to +40ºC
Environment Protection
IP54 rated
Minimum PC Requirements Processor 500MHz, 128Mb RAM, 40Mb hard drive, serial port
or one free USB port
PC OS Requirements
Microsoft Windows NT/2000/XP
Walking Stick Software
The ACFM for Rails software package provides complete Walking Stick instrument control,
data collection, storage and analysis. The software design is user-friendly and intuitive,
suitable for touch screen PCs and has been developed to run on portable and desktop PCs
which are on Microsoft Windows XP/Vista.
The software package is provided in two parts:
•
Inspection PC - for on-track inspection.
•
Runs on a small-form ruggedized PC/laptop integrated into the Walking Stick frame.
•
Performs instrument control and data collection.
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•
Automatically analyses the data on-site and can produce yard-by-yard inspection
summary reports.
•
Produces audible and visual indications of defect analysis results.
•
BaseStation PC - for off-track storage and reporting.
•
Office-based PC or trackside laptop PC.
•
Provides long term data storage from multiple walking stick inspection PCs.
•
Produces summary and job reports.
•
Provides means of post-inspection analysis and auditing.
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8
Acoustic Emission
8.1
Introduction
Acoustic emission (AE) uses the sound waves which are produced when a material
undergoes stress (internal change), as a result of an external force. AE occurs when a
small surface displacement of a material produced due to stress waves generated as the
energy in a material, or on its surface is released rapidly. The wave generated by the
source is of practical interest in methods used to stimulate and capture AE in a controlled
fashion, for study and/or use in inspection, quality control, system feedback, process
monitoring and others.
Fig.8-1 Inspection techniques scheme (Vopilkin et al. 2008)
Applications
•
Detection of debonding of bridge deck from the girders,
•
Detection of delaminations,
•
Detection of wire breaks in cable stays, and
•
Detection of crack or damage in structural members including rails.
Advantages
A stressed structure generates mechanical wave motions known as “acoustic emission”
(AE) via elementary processes of deformation and fracture near a crack edge (e.g.
debonding or delamination). If there is a monitoring system which localises the AE source
at different times, it is possible to monitor the tip velocity of a propagating crack. This
method is advantageous due to its passive nature, and ultrasonic signal excitations are not
required.
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Limitations
The sensors within the structure monitor AE signals and relate the debonding or
delamination to the number of AE signals received. The limitation of AE comes from the fact
that existing structures cannot provide AE signal history. As a result, estimating the
structural integrity of existing structures proves challenging.
8.2
Hardware and software
Technical characteristics (Vopilkin et al. 2008) for a main system include:

Pulse generator: bipolar with varying length

Pulse length adjusting: 0.1…1 ms

Pulse amplitude: 50, 100, 150 V

TVG range (200 ms diapason): at least 30 dB

Minimal scanning step size: 0.01 mm

Probes frequencies : 2.5 and 5.0 MHz

Acoustical channels quantity: 8

Time for inspection of single defected area: about 3 min

Scanning zone along the rail: 250 mm

Operating temperature range: from minus 30° C to plus 40° C

Flaws sizing accuracy: ± 2 mm

Power supply: autonomic storage battery 12 V
(a)
(b)
Fig.8-2 Acoustical holography system: (a) Common view. (b) Scanning device on the rail
mock-up (Vopilkin et al. 2008)
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8.2.1
Case one: Vallen Sensor Tester
Table 8-1 Certain frequency ranges have been proven to be best suitable for specific
applications (Vallen Systeme GmbH 2012).
Application
Corrosion screening of flat bottom
storage tanks
Leakage detection in water/oil
pipelines
Hot reheat pipe crack detection
Integrity testing of pressure vessels
Partial discharge detection
Integrity testing of metallic structures
Integrity testing of composite materials
Integrity testing of concrete structures
Drying process monitoring of
plants/wood
AE-testing of small specimen
20-100 kHz
X
100-400 kHz
>400 kHz
X
X (when noise is low)
X
X
X
X
X
X
X
X
Software
The software depends on the data acquisition system used and data analysis software has
to be adapted to the specific application on detecting debonding of the deck from the
girders and delamination.
Speed
It is anticipated that the sensors are permanently attached to the structure and that the data
is available immediately.
Pressure Excitation
Pressure excitation couples the AE-sensor that is used in testing with a wideband ultrasonic
emitter. The emitter is stimulated by a continuous sine wave with frequency over the range
of interest. The RMS signal level of the AE-sensor under test is plotted in dB versus
frequency, whereby 0 dB refers to a AE-sensor output of 1 V at an excitation of 1 μbar.
This testing method allows for a uniform exciting displacement over the entire crystal face
and is fast and easy to reproduce.
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Table 8-2 Customers having the Vallen Sensor Tester (VST) can qualitatively reproduce the
frequency response curves with the pressure excitation settings (Vallen Systeme GmbH
2012)
Output Voltage
Pressure Excitation:
0.1 VRMS (0.05 VRMS if preamplifier gain > 40 dB)
Offset
-114 dB – external gain (+ 6 dB if preamplifier gain > 40 dB)
Cable length used
RG178m 1.2 m, if no other length is stated for the frequency
curve.
8.2.2
Case two: Olympus AE-sensors
Olympus V103 (ultrasonic wideband Sensor) is used as emitter. AE-sensor under test is
coupled face-to-face to emitter using a suited couplant (e.g. light machine oil).
For the VS30-V and VS75-V an Olympus V101 is used instead of the V103. The other
settings can be seen from the legends in the frequency curves.
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Table 8-3 Example AE sensors for standard environment (Vallen Systeme GmbH 2012).
Freq.
Range
[kHz]
fPeak Size DxH
[mm]
[kHz]
Temp.
Connector
Range [°C]
Capa- Magnetic
city
holder
[pF]
VS30-V
VS30-SIC46dB
25-80
25-80
Flat
Flat
20.3 x 37
69
28.6 x 51.8 164
-5 to +85
-5 to +85
Microdot
BNC
140
MAG4V
MAG4SI
VS45-H
20-450
275
20.3 x 22
22
-20 to +100 Microdot
270
MAG4H
VS75-V
30-120
75
20.3 x 37
63
-5 to +85
Microdot
140
MAG4V
VS75-SI-40dB
30-120
75
28.6 x 51.8
153
-5 to +85
BNC
MAG4SI
VS75-SIC-34dB 30-120
VS75-SIC-40dB
75
28.6 x 51.8
157
-5 to +85
BNC
MAG4SI
VS150-M
100-450
150
20.3 x 14.3
23
-50 to +100 Microdot
350
MAG4M
VS150-L
100-450
150
20.3 x 14.3
23
-50 to +100 SMC
350
MAG4M
VS150-R
100-450
150
28.6 x 31.5
69
-40 to +85
BNC
350
MAG4R
VS150-RI
100-450
150
28.6 x 31.5
69
-40 to +85
BNC
MAG4R
VS150-RIC
100-450
150
28.6 x 31.5
69
-40 to +85
BNC
MAG4R
VS370-A1
170-590
370
M7x0.75 x
13 5
2.7
-40 to 125
SMC (top)
47
MAG4A1
VS370-A2
170-590
370
8.5 x 13
M7x0 75 x
2.7
-40 to 125
SMC (top)
47
MAG4A1
VS375-M
250-700
375
20.3 x 14.3
21
-50 to +100 Microdot
390
MAG4M
VS375-RIC
250-700
375
28.6 x 31.5
66
-40 to +85
BNC
VS600-A1
390-850
600
M7x0.75 x
13 5
2.5
-40 to 125
SMC (top)
109
MAG4A1
VS600-A2
390-850
600
8.5 x 13
M7x0 75 x
2.5
-40 to 125
SMC (top)
109
MAG4A1
SMA/BNC
200
VS600-Z1
550-730
600
4.75 x 5.8
AE-sensor
Model
(c) The SMARTRAIL Consortium 2012
Weight
[g]
0.83
MAG4R
-10 to +110
-
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9
9.1
Ground penetrating radar
Introduction
Ground penetration radar (GPR) is one of the successful NDT methods to investigate
railway embankments, track bed and building grounds. It is a relatively slow technology as
the GPR antenna must remain close to the surface under test. The benefit of this technique
lies in the depth of penetration. Low-frequency ground-coupled systems can penetrate
certain soils over 3 metres whilst higher frequency systems can be used to identify nearsurface anomalies, detect voids, locate rebar and dowel bars at excellent resolution.
Fig.9-1 shows example Generation of a GPR profile for ballast and subballast (De Bold et
al. 2011).
Fig.9-1 Generation of a GPR profile for ballast and subballast (De Bold et al. 2011)
Advantages

The technology is proven and mature.

Hardware and software are readily available.
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Limitations

GPR data analysis can be difficult and often requires an expert.

GPR data analysis cannot discriminate between layers with similar dielectrics.

Most defects and anomalies in the pavement structure can be detected only
through visual interpretation of the data.

GPR data is not effective in conductive environments (i.e., where clay layers
with significant moisture contents are present).

The maximum data collection speed for this technology is about 10 mph.
Speed
Accuracy and Precision

In terms of the data, repeatability and reproducibility have been good as long as
site conditions have not changed and the equipment has been properly
calibrated and maintained.

From TRB (2009), GCGPR equipment usually costs between $50,000 and
$60,000 for multiple antenna configurations.

Training of operators costs approximately $1,000 per person. Training of data
analyzers also costs approximately $1,000 per person.

GPR calibration and maintenance usually costs around $2,000 per event.
Costs
9.2
Hardware and software
Technical characteristics including specifications on GPR methods will be described using
some typical examples.
Fig.9-2 GSSI’s SIR-30 (GSSI 2013)
GSSI’s newest generation control unit, the SIR-30, is a High-Performance Multi-Channel
GPR Data Acquisition System. The typical uses include: Rail bed inspection, Road
structure assessment, Utility designation, and Bridge deck inspection. As the basis of a
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high-speed data collection system, the SIR-30 is ideal for: measuring pavement layer
thickness, detection of cavities, airport runway assessment, detection of fouled/clean ballast
and utility detection.
Table 9-1 System for the SIR-30 (GSSI 2013)
Antenna Support
Compatible with all GSSI antennas
Number of
Records data from 1 to 4 hardware channels simultaneously; two 4
Channels
channel systems can be connected to form an 8 channel system
Data Storage
Internal memory: 4 channel 500 GB Internal SSD
2 channel 250 GB Internal SSD GPS data logged internally
Display Modes
Linescan and O-scope.
In Linescan display, 256 color bins are used to represent the
amplitude and polarity of the signal
Operational Modes External laptop, standalone with external monitor and keyboard or
remote command set
Table 9-2 Data Acquisition (GSSI 2013)
Data Format
RADAN (.dzt)
Scan Rate
Output Data Resolution: 32-bit
Examples
1-4 Channels @ 100 KHz PRF
Samples:
256 512 1024 2048 4096 8192 16,384
Max Rate (scans/Sec): 326 178 93
48
24
12
8
1-4 Channels @ 800 KHz PRF
Samples:
256 512 1024 2048 4096 8192
16,384
Max Rate (scans/Sec): 1449 990 606 341 182
94
48
Operating Modes
Continuous (time) or survey wheel (distance triggered)
Time Range
0-20,000 nanoseconds full scale, user-selectable
Gain: manual adjustment from -42 to +126 dB.
Number of segments in gain curve is user-selectable from 1 to 8.
Standard RealInfinite Impulse Response (IIR) - Low and High Pass, vertical and
Time Filters
horizontal
Finite Impulse Response (FIR) - Low and High Pass, vertical and
horizontal
Advanced RealMigration, Surface Position Tracking, Signal Floor Tracking,
Time Filters
Adaptive Background Removal
External Marker
Three different inputs/codes: Antenna, Back panel, Accessory
connector
Automatic System Storage of an unlimited number of system setup files for different
Setups
survey conditions and/or antenna deployment configurations
Automatic Antenna Automatic recognition of Smart Antennas to allow maximum
Recognition
compliant transmit rate
Operating (GSSI 2013)
Operating
Temperature
Power
Transmit Rate
-10°C to 50°C external (14°F to 122°F)
260W max (120W typical) at 95-250VAC 50/60Hz or +10VDC to
+28VDC
Up to 800 KHz (International), US/Canada and CE rates depend on
antenna model
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Input / Output (GSSI 2013)
Available Ports
Antenna inputs (2 or 4), Survey wheel, Marker, DC power input,
Serial RS232 (GPS port), Sync connector, Accessory connector,
HDMI video, Ethernet to PC, 4 USB ports
The SIR-30 has a maximum, channel-independent, transmit rate of up to 800 KHz. At this
transmit rate, one 2 GHz horn antenna can obtain data at a scan spacing of 4 cm (1.5 in)
while traveling at 142 km/hr (88 miles/hr). And, because the transmit rate is independent of
the number of channels, the same 4 cm (1.5 in) scan density can be obtained on each
antenna whether collecting with 1, 2, 3, or 4 antennas at the same time.
Consequently, with the SIR-30, four 2 GHz antennas* can be mounted side-by-side and
each antenna can obtain 256 sample/scan data at a 2 cm (0.8 inch) spacing at 104 km/hour
(64 miles/hr) or 208 km/hr (129 miles/hr) at a spacing of 4 cm. This amounts to a total of
about 5,792 scans per second.
Fig.9-3 GPS different sensors mounted in front of the train of the Rhätische Bahn,
Switzerland. (Kathage et al., 2005)
Table 9-3 Devices used for a typical GPR survey (Kathage et al., 2005) include:
Device
SIR-20 GPR control unit
400 MHz horn antenna
1000 MHz horn antenna
GPS system Leica SR 510
Digital frame camera 6.0 mm
PC for camera and GPS
Antenna cables
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2
3
1
1
1
1
4
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Flat screen 15’’
Keyboard
Siemens Doppler-Radar
External hard-disk for data backup
Distance measurement device
1
1
1
1
1
The following (Kathage et al., 2005) illustrates the typical procedure and key parameters of
a railway line GPR survey project.
GPR Data collection:

4 profiles per line: rails centre line, field side, rails side, and “ballast magnifier”;

>80 km/h

Scale 1:250

DGPS synchronised digital video

Information on depth up to 4 m
Data processing:

Scaling of survey profiles: referencing within 1 m accuracy, and horizontal
discontinuities

Geometrical rail data

Raw GPR data: gain adjustment, filtering, and synchronisation
Interpretation:

Proposal for drill core locations

Drill core sampling

Calibration of radargrams and graphical integration of drill cores information in
radargrams

Layer tracking

First visual data analysis: continuous profile description for defects, layers,
compacted layer, and moisture accumulations

Viewer programme for integrated display for radargrams, layer interfaces, drill
core graphics, geometrical rail data, video records, and field notes

Continuous section display as 2D diagram

Visualisation of profiles perpendicular to rails

Export of interpretation results to CAD system

Presentation of results and consultancy
Result:
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Doppler Radar sensors (module KMY 24) are used to detect movements within their
sensitivity range without measuring the absolute distance to the object.
Table 9-3 Key technical data of the KMY 24 motion sensor (Lohninger 1996)
Measured min. value typ. max.
2.4
2.45
2.4835
Unit
GHz
8
5
12
22
10
8
15.6
dBm
m
V
mA
–45
–36
dBm
3
ms
Operating frequency
Equivalent isotropic radiated
power at operating frequency
Range
Operating voltage
10.8
Operating current
Radiated harmonic power
1st/2nd/3rd harmonics
Time between turn-on
and first detection
Fig.9-4 Vertical/horizontal diagram of the patch antenna at 2.45 GHz Doppler Radar
sensors (Lohninger 1996)
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Fig.9-5 the Subsite® 2450GR ground penetrating radar system (Subsite 2013)
The Subsite® 2450GR ground penetrating radar system is designed to help subsurface
utility engineers and other contractors locate any type of utility conduit or piping—including
PVC pipes—beneath soil, rock, pavements and other surfaces. The 2450GR's advanced
locating capability makes it ideal for a wide range of other applications, including urban
planning, exploratory and archeological digs, void and sinkhole detection, concrete
detection, and locating underground storage tanks.
Radar Power Requirements:

Battery operating time: >10 hours

Power supply: 12V sealed lead acid, 12 Ah
Mechanical

Operating temperature: 14° F to 104° F -10° C to 40° C

Humidity: 100% (sealed)

Weight, without battery or PC: 60.6 lb 27.5 kg

Weight, without PC: 68.6 lb 31.1 kg

Weight, total: 73.9 lb 33.5 kg
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
Width: 21 in 533 mm

Length, handle fully extended: 50 in 1.27 m

Length, folded: 40 in 1.02 m

Height, handle fully extended: 39.5 in 1 m

Height, folded: 20.5 in 521 mm
Dual Frequency

Antenna technology: Ultra-wide band, ground coupled, shielded dipole

Typical range: 0.32 ft - 8.2 ft 0.1 m - 2.5 m

Maximum range: 0.32 ft - 19.7 ft 0.1 m - 6 m
Table 9-4 2450GR Specifications (Subsite 2013)
System
U.S.
Metric
Survey path width
19.7 in
500 mm
Recording channels
2
Transmitting frequency
200 kHz
Typical antenna frequency
250 MHz and 700 MHz
Typical collection speed (scans/second)
100
Typical collection speed at 2-in (5 cm) sampling 5.6 mph
interval
9 km/h
Display mode
Gray scale/color palette
Zoom
Up to 4x
Data storage
Laptop hard drive
Maximum profile length
Virtually unlimited
Stored data format: Raw data (for further data analysis)
Setting of GPR propagation velocity (to get accurate evaluation of depth of detected
targets): Ground truth or hyperbola fitting methods
Reading of pipe position/depth: Software cursor
System output: Printable radar map with descriptor of detected utilities
Key Features

Locates both metallic and non-metallic pipes and cables to allow one-pass
locates at depths of up to 19.7 feet (6 m).

With 5.6 mph (9 km/h) survey speed and digitally controlled radar, the 2450GR
provides fast, clear images.
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
Earth-engaged antenna provides better contact on uneven terrain and reduces
signal loss.

Dual-frequency antenna simultaneously sweeps in two frequencies; this allows
the operator to see both deep and shallow objects simultaneously.

The 2450GR folds up into a size that is easy to transport.
Rugged, four-wheel cart design allows the operator to scan in the easiest and roughest
conditions.
Software
All vendors provide data acquisition software that also shows a real-time visual display of
the data. Various software packages can be used to analyse the data. For instance, The
acquisition parameters (Su et al. 2011) for a test set are as follows:

Acquisition speed: typical walking speed (about 1.5 m/s); Horizontal sampling
interval: 0.012 m to 0.06 m;

Samples per scan: 512;

Antenna orientation: in y direction for the 400 MHz antenna and both y and x
directions for the 2 GHz antenna.
Fig.9-6 Interpretation elements in GeoExplorer (Kathage et al., 2005).
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10 Falling Weight Deflectometer
10.1 Introduction
A falling weight deflectometer (FWD) operates by dropping a known weight onto a circular
plate resting on the surface of interest. This imparts a physical impulse into the ground,
which is measured by one or more geophones. The geophones are located at the point of
impact and, often, at 300mm intervals from the point of impact in order to measure the
velocity profile of the surface response to the load. Fig.10-1 shows the FWD principle.
Fig. 10-1 Principles of FWD (Loizos et al. 2003, Brandley 2007). Where, c is the damping
co-efficient, m is the impinging mass, and k is the stiffness of the spring.
The deflections of the loaded sleeper, the ballast in the adjacent crib and the ballast in the
next crib, are interpreted as corresponding to the sleeper deflection, the deflection of the
loaded ballast, and the deflection of the formation, respectively (Brough et al., 2003).
A Light Weight Deflectometer (LWD) is a portable falling weight deflectometer. It is used
primarily to test insitu base and subgrade moduli during construction.
A Heavy Weight Deflectometer (HWD) is a falling weight deflectometer that uses higher
loads, used primarily for testing airport pavements.
A Rolling Weight Deflectometer (RWD) is a deflectometer that can gather data at a much
higher speed (as high as 55 mph) than the FWD. It is a specially designed tractor-trailer
with laser measuring devices mounted on a beam under the trailer. Another advantage of
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the RWD over the FWD is that it can gather continuous deflection data as opposed to
discrete deflection data collected by the FWD.
Fig.10-2 Schematic diagram of FWD in operation and the loading plate (COST-Transport
2005).
The test materials are described in ASTM D 4694, and the test method is defined in ASTM
D 4695.
Applications
The FWD is a powerful tool for directly measuring the performance characteristics of a
trackbed. It can be used at a more regular spacing than can trial pits to give spot values for
the stiffness parameters (Sharpe et al.1998). Falling Weight Deflectometer (FWD) is
usually used in the pavement industry in order to a measure static stiffness of pavement.
Similar special equipment has been developed for the railway industry (De Bold et al.
2011).
Advantages
 The measured deflections and the calculated stiffness moduli of both lines can be
compared
 The results of this comparison may yield indicative information on the residual life of
the pavement
 Test large area very quickly
• Run 1 test per minute
• Grid pattern to get general picture
 Data compiled and viewed in real-time
 Entire test can be run from a laptop inside vehicle
 Non-destructive test
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Limitations
 Its results are often dependent on such factors as the particular model of tester
used, the specific testing procedure, and the method of back-calculation.
 No fundamental criteria, namely subgrade strains,
 The stability of the FWD trailer machine is strictly.
 The costs and time of the testing are relatively high.
Benefits
Provision of the correct stiffness characteristics may have the following benefits:
 improved track geometry,
 reduced rate of deterioration of track geometry,
 reduce need for tamping,
 maximised ballast life (by reducing ballast breakdown due to high dynamic loads
and frequent tamping),
 increased critical velocity and hence a smaller "bow wave" effect.
10.2 Hardware and software
Components (Brandley 2007)
 Load Cell
 LVDT, Geophones, Accelerometers for displacement measurement
 Infrared temperature gages for temperature measurement
 Electronic Distance Measurement
 Control/Data Acquisition Unit
 All instrumentation used simultaneously
 Deflection profile is key output
 Temperature and load data used with deflections to back-calculate pavement
structure characteristics
Instrumentation Specifications
 Load Cells
o Range:
0 - 60,000 lb.
o Accuracy:
2%
 Displacement
o Range:
0 to 100 mils (0 to 2500 mm)
o Accuracy:
±0.04 mils (1 mm)
 Temperature
o Range:
0 to 750°F
o Accuracy:
±0.5°F
 A circular load plate - typically 300mm diameter
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10.2.1 Case one: work at the University of Edinburgh
An instrumented 12lb impact-impulse hammer with built-in load cell that converted the
impact force into an electrical signal was used to impact various parts of the track and the
vibration response was recorded using a nearby transducer. The 12lb hammer was chosen
over smaller models because it imparts the largest force and has the lowest frequency
content. Two different hammer tips were used, one made from rubber and one made from
vinyl. A velocity transducer (geophone) and a displacement transducer were used to record
the hammer impact responses. Later analysis found that the displacement transducer data
was not suitable as the low frequency performance was less linear. The geophone used
was a low frequency model and captured the data of interest, i.e., less than 100Hz,
whereas the displacement transducer did not.
A National Instruments dynamic signal conditioning unit with USB connectivity was used to
supply power and condition the signals from the hammer and geophone. National
Instruments software was used to record the data on a laptop PC. A programme was
constructed with the software to manage the devices and collect, analyse, display, and
record the data.
The general testing procedure for each crib was to impart a force onto the structure using
both the vinyl and rubber hammer tip with the geophone located at a distance of
500mm (this distance was found to produce the clearest and most consistent results). The
test was repeated three times at cribs 1, 2, 3, 4, 6, 8, 10, 12, 14, and 16.
The three main structural components were tested using the following setup configurations:
Setup 1 Ballast impacted with hammer and response from 1 ballast measured – “Hit
Ballast, Measure Ballast”.
Setup 2 Ballast impacted with hammer and response from tie measured – “Hit
Ballast, Measure Tie”.
Setup 3 Ballast impacted with hammer and response from rail measured – “Hit
Ballast, Measure Rail”.
Setup 4 Rail impacted with hammer and response from ballast measured – “Hit
Rail, Measure Ballast”.
Setup 5 Tie impacted with hammer and response from ballast measured – “Hit Tie,
Measure Ballast”.
When the impulse hammer was impacted on the ballast, a metal strike plate was used for
the hammer on the ballast. This would be bedded into the ballast with a sledge hammer
prior to testing.
When the response from the ballast was measured, the geophone would be affixed to a
15cm spike with a square flat head that would be driven into the ballast with a sledge
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hammer prior to testing. A 2 mm thick strip of plasticine was used as an effective coupling
material. The experimental setup is shown in Fig.10-3.
Fig.10-3 Experimental setup schematic and photograph
A typical FRF of a concrete structure can be broken down into three regions (Fig.10-4):
Region 1 0 to 50 or 100Hz – defines the static compliance and is directly related to
stiffness.
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Region 2 100 to 800Hz – the average mobility value inside this range is related to
stiffness.
Region 3 Above 800Hz – data in this region not related to stiffness.
Fig.10-4 Characteristics of an FRF
10.2.2 Case two: work at Nottingham University
Sharpe (1996) identified five separate mechanisms that affect track quality and identified
suitable stiffness parameters for each mechanism (see Table 1).
Table 10-1: Track quality mechanisms and associated stiffness parameters.
Displacement mechanism
Resilient Displacement
Ballast Settlement
Bow Wave Effect
Dynamic Loading
Quasi Static Sleeper Loading
Stiffness Parameter
Absolute Stiffness
Ballast Strain
Critical Velocity
Dynamic Stiffness
Effective Stiffness
The load was applied via a 1.1m long beam shaped to distribute the load to both ends of an
F27 sleeper. This was considered to be the most efficient form of loading since it enabled
the response of a trackbed to sleeper loading to be measured directly. Results have shown
that this loading system produces a load pulse similar to that applied by a single axle of a
train travelling at high speed. At each test location three adjacent sleepers were unclipped
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from the rails to decouple the rail from the trackbed. The geophones were arranged as
shown in Fig.10-4. The load, P, was measured in the centre of the loading beam and the
peak load was adjusted to 125kN.
Fig.10-5 FWD geophone arrangement (Sharpe et al. 1998)
With reference to Fig.10-5, the average of displacements D1, D2 and D3 was taken as the
mean sleeper displacement (DS), the average of displacements D6 and D7 was taken to be
the mean ballast displacement (DB), and the and the displacement D4 was taken to be the
displacement of an adjacent sleeper (DA).
Table 10-2: Definition of key parameters in terms of measured FWD deflections.
Parameter
Ballast Strain Factor (BF)
Dynamic Stiffness (KD)
Effective Stiffness (KE)
(c) The SMARTRAIL Consortium 2012
Definition
DS – DB
P / (DS - (DB + DA) / 2)
P / (DS - DA)
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Fig.10-6 Typical stiffness variations (Sharpe et al. 1998).
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11 Light Weight Deflectometers
11.1 Introduction
The light weight deflectometer (LWD) is one kind of field testing equipment for
determination of stiffness of layers materials in railway infrastructure. LWD can measure
deflections induced by dropping weight (up to 20 kg – hence light weight) using geophones.
It enables the measurement of dynamic deformation modulus for soils, stone or other noncohesive material. The measured data are vital to the construction of railways, buildings
and pavements.
Fig.11-1 Basic principle of light weight deflectometer (Mork 2008)
Applications
•
Test stiffness of granular bases, soils, and fine-grained pavement layers, road
construction, railway track construction, pipeline and cable work, gardening and
landscaping.
•
Determine if chemical stabilization of subgrade is effective.
Advantages
•
Portable device that can be used in areas where falling-weight deflectometers
(FWDs) cannot be used.
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•
Easy to operate, and small enough to be used at any place (especially construction
•
sites)Lower initial cost than an ordinary FWD (1/10)
Limitations
•
Cannot impart loads similar to truck traffic loads;
•
Measurements at discrete points.
Unit shown has single load and deflection sensor so it provides a composite stiffness for the
layer being tested. Multisensor units (up to three sensors) are available. Need to improve
software to obtain multilayer stiffness values.
Accuracy and Precision
Accuracy, repeatability, and reproducibility of the data are considered good as long
as the geophones and load cells are properly maintained and calibrated.
Speed
•
Data collection at each measurement point is within 10 s.
•
Data analysis can be performed within 1 h.
Costs
In 2009 (TRB 2009) Costs may range from $5,000 to $10,000, depending on the
manufacturer.
LWD products in the market
•
Dynatest LWD
•
Prima 100, CarlBro (previously Phoenix)
•
Light Drop Weight (LDW), Germany
•
Loadman, Finland
•
PAVELWD HMP Light Weight Falling Deflectometer, UK
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11.2 Hardware and software
The portable Light Weight Deflectometer (FWD) consists of a load plate with a geophone
and load cell. Two additional geophones can be mounted on the device to obtain a
deflection bowl.
11.2.1 Case one: Terratest 3000 GPS
An example tester is Terratest 3000 GPS (Cooper Technology 2013).
Key Features
•
Fully equipped compact device
•
Weatherproof box with external control buttons, protecting the electronics
•
GPS system with display in satellite picture
•
Integrated printer for immediate printout
•
Test saving on chip card
•
Internal memory for up to 2000 tests
•
Text input function
•
High-performance rechargeable battery
•
User friendly PC-software for evaluation and management of measured data
Calibration & Maintenance: Calibration, Annual Service and Maintenance Contracts are
available for this device. This device should be checked and calibrated annually.
Accessories
•
CRT-TERRA-LD-10KG: Additional weight for measuring Evd 15-70 MN/m2
•
CRT-TERRA-LD-15KG: Additional weight for measuring Evd 70-120 MN/m2
•
CRT-TERRA-CABLE2.5M: Measuring cable, 2.5 Meter incl. push-pull connectors
from Lemo
•
CRT-TERRA-CABLE2.5E: Extension cable, 2.5 Meter incl. push-pull connectors
from Lemo
•
CRT-TERRA-USBCABLE: 1.0 meter USB cable
•
CRT-TERRA-CARELLO: The comfortable fork system
•
CRT-TERRA-BOXMILANO: For transport of 10kg device
•
CRT-TERRA-BOXROMA: For transport of 10kg and 15kg device
•
CRT-TERRA-MAGPLATE: Magnet plate for placing on the ground
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•
CRT-TERRA-CARDS: 3 chip cards, reusable
•
CRT-TERRA-CARDREADER: Card reader
System Elements
The CRT-TERRA is comprised of:
•
Loading device with 10 kg drop weight
•
Load plate 300 mm
•
Integrated GPS system
•
Graphic display
•
Mini-printer
•
Chip card for saving test results
•
External chip card reader for PC connection
•
Connection cable testing computer/load
plate
•
Rechargeable battery to perform over 1000
tests when fully charged
•
Charger (110/220 volt), car charger lead (12
volt)
Fig.11-1 Terratest 3000 GPS
(Cooper Technology 2013).
Software for Terratest 3000 GPS
•
User-friendly software with integrated Google® Earth Interface
•
Measurement can be shown in a Google® Earth satellite picture with the measured
value, date and time
•
The
GPS
coordinates
will
automatically
be
converted
Gauss-Krüger coordinates, so data can be uploaded to CAD-plans
•
Individual data records as well as a statistical analysis of the entire testing area as
specified in ASTM E2835-11 can be created
•
Testing results are analyzed and archived automatically and necessary self
monitoring is achieved
•
The load and deflection data can be imported into a Microsoft Excel spreadsheet for
data analysis.
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Fig.11-2 software for Software for Terratest 3000 GPS (Cooper Technology 2013).
11.2.2 Case two: PRIMA100
PRIMA100 (Cooper Technology 2013) is another example tester. Specifications for
PRIMA100 (Cooper Technology 2013) are as follows:
Estimated Weight
•
Weight, standard equipment <20kg
•
Weight incl. all weights <30kg
•
Drop weight 10-15kg
•
Maximum drop height 85cm
•
Guide rod: D22mm stainless steel 316
Load Characteristics
•
Load plate: D100, 200 or 300mm
•
Load range: 1-200kN
•
Load pulse duration: 15-30ms
•
Load pulse shape: Essentially half-sine
•
Load pulse rise time: 8-15ms
Load Cell
•
Load cell accuracy: 1% +/- 0.1 kN
•
Load resolution: 0.1kN (1KPa)
•
Frequency range: 0-400Hz
Deflector sensor
•
Sensor type: Seismic Velocity Transducer
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•
Number of geophones: 1-3
•
Geophone accuracy: Better than +/-2%
•
Geophone resolution: 1micron
•
Geophone range: 1-2200microns
•
Frequency range: 0.2-300Hz
System Elements
•
100mm loading plate
•
300mm loading plate.
•
10kg drop weight (up to 15kg drop weight is possible).
•
4 rubber buffers.
•
1 load cell for force measurement.
•
1 centre deflection sensor (up to 3 deflection sensors are possible).
•
Interface box and communication cable for laptop / PC.
•
Measuring and data collection software (Windows 98/2000/NT/XP).
•
RoSy compaction.
•
E-modulus calculation/design software for up to 4 layer structures.
•
Manuals in English (1pc).
•
24 months warranty on LWD part.
•
CE marked
•
ISO 9001/2000
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11.2.3 ASTM E2583-07Dynatest 3031 LWD
Fig.11-3 LWD, FWD and DCP used for pilot study (Mork 2008)
•
It has a basic 10 kg falling mass (+5kg)
•
During the test, the falling mass impacts the plate, producing a load pulse up to 15
kN of 15 – 25 ms duration.
•
The center geophone sensor measures the deflection caused by the mass impact
on the loading plate. (+2 more geophones optional)
•
The diameter of the loading plate can easily be varied between 150 and 300 mm
•
The software associated with the equipment is LWDmod, which uses the same
principle as ELmod for Dynatest FWD.
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Fig.11-4 LWDmod used for analysis
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12 Electric Friction Cone Penetrometer Test (CPT)
12.1 Introduction
The Cone Penetrometer Test involves pushing an instrumented cone; tip first, into the
ground at a controlled rate between 1.5-2.5 cm/s. The resolution of the CPT in delineating
stratigraphic layers is related to the size of the cone tip. It is a valuable method of assessing
subsurface stratigraphy associated with soft materials, discontinuous lenses, organic
materials (peat), potentially liquefiable materials (silt, sands and granule gravel), and
landslides. The tip resistance is measured by load cells located just behind the tapered
cone. The tip resistance is theoretically related to undrained shear strength of a saturated
cohesive material, while the sleeve friction is theoretically related to the friction of the
horizon being penetrated.
Fig.12-1 shows a cone penetration testing and the data acquisition system.
Fig.12-1 Cone Penetration Testing (source: NGI, UMass Amherst, Cone Penetration
Testing
(CPT),
www.ead.anl.gov/new/newsdocs/DeGroot_Quick_Introduction.pdf,
accessed on 17 Feb. 2013).
Applications
•
The CPT is a valuable method used to assess the condition of subgrade, for
example subsurface stratigraphy associated with soft or organic materials like peat,
liquefiable materials and landslides. The technique is suitable for:
•
determination of consolidation characteristics
•
measuring pore water pressures
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•
penetration of dense sand layers
•
operating depths up to 60m+
•
dissipation testing (available on request)
•
Soil profile (stratigraphy)
•
Estimation of geotechnical parameters (strength, liquefaction resistance, shear
wave velocity
•
in-situ water content, porewater pressure, shear modulus, shear strength)
•
Evaluation of groundwater conditions
•
Geo-environmental: distribution and composition of contaminants
Advantages:
•
Continuous data
•
Elimination of operator error
•
Reliable, repeatable test results
•
Greater delineation of strata since readings are taken every 2cm
•
Repeatable, reliable penetration details
•
High quality, real time results
•
Using the instant CPT results, engineers can select, on site, the best locations for
sampling, dissipations tests etc.
•
Minimal soil disturbance
•
High productivity (up to 150m tested per day)
•
CPT platform can be used for deploying high quality push fixed piston samplers
•
More manageable data handling
Limitations:
•
Inability to penetrate through gravels and cobbles
•
Lack of sampling
•
Cone penetration testing cannot be carried out through rock layers.
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12.2 Hardware and software
Figs.10-2 and 10-3 show schematic section through a piezocone head (ASTM D5778), and
an electric friction-cone penetrometer tip (ASTM D 3441-94, ASTM 1994), respectively.
Fig.12-2 Schematic section through a piezocone head, showing the piezo-element and
friction sleeve. Adapted from ASTM D5778.
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Fig.12-3 Schematic section through an electric friction-cone penetrometer tip, taken from
ASTM D 3441-94 (ASTM, 1994).
12.2.1 Case one: Cone Penetrometer from JK Group
Maximum depth of 860mm.
The Electric Friction Cone Penetrometer (EFCP) (JK Group 2013) is mounted on a 6x4
Bogey drive truck, with:
•
35mm diameter rods with an instrumental tip
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•
hydraulic system capable of providing thrust in excess of 15t
•
refusal at 50MPa tip pressure
•
standard and piezocone tips
•
continuous data logging and interpretation
•
operating height 4.75/6.05m
•
operating width 2.5m
Table 12-1 Drill Rig Specifications (JK Group 2013)
JK500
(Hino
500GT)
AU51XO
Dimension / rig
type
A HEIGHT FOR
WORK (mast
vertical, ground
surface horizontal
– add up to 1
metre for slopes
up to 1:10 or 6
deg)
B HEIGHT FOR
TRAVEL ON
SITE (mast
horizontal)
C HEIGHT FOR
TRAVEL ON
ROAD (mast
horizontal,
including truck)
D WIDTH FOR
TRAVEL ON
SITE (see note
below regarding
safe work) *
E RIG LENGTH
FOR TRAVEL ON
SITE (mast
horizontal)
F LENGTH FOR
TRAVEL ON
ROAD (including
truck)
G WORKING RIG
LENGTH (mast
JK350
(Isuzu)
ZGX429
JK250
(Nissan UD)
YNW208
EFCP
(Freight-liner)
AV74SL
Melvelle
Mast
Tracked
Truck
Mobile
9.5m
Truck
mounted
6.2m #
4.1m
4.8m
2.2m
3.8m
3.3m
2.2m
3.5m
2.0m
3.8m
3.3m
3.4m
3.5m
2.3m
2.5m
2.2m
1.51m
2.5m
0.8m
9.8m
7.1m
3.3m
9.4m
N/A
9.8m
7.1m
7.8m
9.4m
N/A
9.8m
7.1m
3.1m
9.4m
N/A
Truck mounted
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vertical) **
SUITABLE UP
TO DEPTH ***
WEIGHT OF RIG
ON SITE
REGISTERED
VEHICLE
WEIGHT (TARE)
MAX WEIGHT
ON ROAD (GVM)
100m
60m
40m
44m
15m
13.0t
8.5t
3.6t +equip
24.0t
500kg
10.9t
6.1t
4.1t
24.0t
500kg
13.0t
8.5t
10.4t
24.0t
N/A
Notes
#
JK350
Extension can be removed for max height of 6.6m upon request.
^
Eziprobe Can be operated in limited capacity with reduced headroom
*
All Rigs
Room to move around equipment for safe operation is required. Additional
2m required if recirculation of drilling mud is required when coring.
**
All Rigs
Space is required for equipment handling during operation. Note also that
length required for unloading = travel length + rig length + ramp length.
***
All Rigs
May require support truck for equipment in excess of standard equipment
load. Remember to consider this when quoting.
12.2.2 Case two: Software CPeT-IT
CPeT-IT (Geologismiki 2013) is an easy to use yet detailed software package for the
interpretation of Cone Penetration Test (CPTu) data. CPeT-IT is the result of a collaborative
effort with Gregg Drilling Inc., a leading company in geotechnical site investigation and cone
penetration testing (CPT) and Professor Peter Robertson, co-author of the comprehensive
text book on the CPT.
Main Characteristics
•
Imports raw Cone Penetration Test data from any ASCII text file
•
Supports input and output in both the SI and Imperial unit systems
•
Tabular presentation of all interpretation results
•
Graphical presentation of all interpretation results
•
Analytic reports for every level of interpretation
•
Overlay report for selected CPTU files
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Dissipation data interpretation module
•
Direct settlements calculation module (for sands only)
•
Single pile bearing capacity calculation
•
Typical geotechnical section creation
•
2D cross section maker module
12.2.3 Case three: Software CPT Tool 3
For CPT Tool 3 (Datgel Data Solutions 2013), Work without limits as you define which types
of soil data to present in log, fence, cross-section and graph reports.
•
Define correlation formulas and reports
•
Preconfigured soil parameter and liquefaction correlations
•
300 customisable log, fence, cross-section and graph reports
CPT Tool 3 places advanced reporting directly in the hands of geotechnical engineers with
code-free report definition and an array of formula configurations, analysis and report
options unmatched in cone penetration testing.
Speed up soil data interpretation with rich-data visualisation in any situation, adapting
reporting output to changing requirements and conditions across projects. CPT Tool 3 is the
third release in Datgel’s CPT series and an add-on for gINT software.
Other geotechnical features:
•
Import CPT data files in numerous formats
•
Choose SI, English, or configure the units to suit your needs
•
Soil behaviour type correlations
•
Pile axial capacity
•
Dissipation test analysis
•
Seismic cone presentation
•
Tools to summarise data into characteristic values and layers
•
Comparison logs showing two PointIDs with your choice of parameters
•
Performance and utility features
•
Support for Access and SQL Server database formats (requires gINT Professional
Plus)
•
Multi-threaded calculation
•
Data correction tool - adjust measured data after it’s imported
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13 Dynamic Cone Penetrometer
13.1 Introduction
The Dynamic Cone Penetration Test (DCPT) provides a measure of a material’s in-situ
resistance to penetration. The DCPT is performed by dropping a hammer from a certain fall
height and measuring a penetration depth per blow for each tested depth. The shape of the
dynamic cone is similar to that of the penetrometer used in the cone penetration test (CPT).
The dynamic cone penetration test shows features of both the CPT and the standard
penetration test. The penetration of the cone is measured after each blow and is recorded
to provide a continuous measure of shearing resistance up to 5 feet below the ground
surface.
Applications
•
Measure thickness and stiffness of natural soils and fine-grained unbound granular
bases, and
•
Determine if chemical stabilization of subgrade is effective.
Advantages
•
Portable,
•
Easy to use,
•
Easy to observe and measure stiffness, and
•
Nonnuclear technology.
Limitations
•
Labour intensive,
•
Measurements at discrete points, and
•
Slow.
Software
•
Data is recorded manually with the device.
•
Equipment can be installed with the DCP to record the data electronically. Data can
be input into a Microsoft Excel or other spreadsheet program.
Speed
•
For most earthworks, data collection takes approximately 5 min per location.
Accuracy and Precision
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•
Accuracy, repeatability and reproducibility are good as long as the device is in
proper working condition.
Costs
•
From TRB (2009), the manual DCP on 2009 costs around $2,000. Automated DCPs
have been developed and their estimated cost is $40,000.
13.2 Hardware and software
Dynamic cone penetrometer (DCP) with measuring tape or other measurement device.
13.2.1 Case one: Humboldt’s DCP
The example Hardware and software here are from Humboldt (2013). Standard DCP
components include: Upper Rod and Hammer (Mass), Scale and Lower Rod showing
Disposable Cone.
Fig.13.1 Example components of DCP (adapted from Humboldt 2013)
13.2.2 Case one: Mn/DOT’s DCP
Dual Mass DCP Benefits include:
•
the ability to immediately determine the location and depth of layers;
•
can be used in both hard and soft soils for pavements (CBR 100% to .05%);
Single-Mass Dynamic Cone Penetrometers:
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Models H-4223 and H-4202 are typically used for foundations. These instruments corelate
to the “N” value for the Standard Penetration Test (SPT) The H-4202 comes with an auger
head, T-handle and multiple extensions are available for insertions up to 20 ft.
H-4218A — Dual 8 kg Mass.
H-4218A Standard, Dual Mass, Dynamic Cone Penetrometer, Includes: 8kg stainless twopart hammer assembly, upper rod, anvil, lower rod with wrench flats, lower rod, reusable
hardened point, cone adapter, 25 disposable cones, vertical scale, hand tools, manual,
software template and deluxe carrying case with wheels. Optional extension rods and
attachments are available to facilitate one-person operation.
H-4218D — Dual 8 kg Mass
H-4218D Deluxe, Dual Mass Dynamic Cone Penetrometer, Includes: 8kg stainless two-part
hammer assembly, 2 upper rods, 2 lower rods with anvils, 6 hardened reusable points, 2
cone adapters, 125 disposable cones, vertical scale, go/no-go gauge for points, hand tools,
manual, software template and deluxe carrying case with wheels. Optional extension rods
and attachments are available to facilitate one-person operation.
H-4219 Heavy-Duty, Dual Mass, Dynamic Cone Penetrometer, Designed in full compliance
with the U.S. Army Corps of Engineers specifications with design improvements to improve
assembly, performance and durability. Features machined taper and grooves on handle for
easier lifting of the mass, as well as heavy-duty rod design. Includes: dual-mass slide
hammer assembly, extension shaft with hardened tip, extension shaft with disposable cone
tip adapter, 100 disposable tips, vertical scale, go/no-go gauge, all necessary wrenches,
user manual with spreadsheet software template and carrying case.
H-4223 Heavy-Duty, Dynamic Cone Penetrometer, Developed for users requiring a more
rugged yet portable design. High-grade materials and design reduce shaft coupling and
thread failures associated with low cost versions. Includes: 10-pound slide hammer
assembly with a 24" drop, two 36" extension shafts with 6" increment markings, wrenches
and a hardened-steel 60° cone tip. All components packed in a heavy-duty carrying case
with wheels for easy transport to the job site.
H-4202 Dynamic Cone Penetrometer Test Set, Ten foot version for use in nearly all types
of soils. Includes: one sliding drive hammer assembly with 15 lb. (6.8 kg) mass; one heat
treated 60° cone penetrometer point with 1 ft. adapter rod; four 30" “E” drill rod extensions;
one auger head; one auger T-handle; four 36" auger extensions, and operating instructions.
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Fig.13-2 DCP design (Mn/DOT, 2013).
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Fig.13-3 DCP top section (Mn/DOT, 2013).
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Fig.13-4 DCP Lower shaft detail (Mn/DOT, 2013).
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Fig.13-5 DCP remote scale and cone tip details (Mn/DOT, 2013).
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14 Soil Resistivity Profiling
14.1 Introduction
The soil resistivity profiling method involves the measurement of the apparent resistivity of
soil and rock as a function of depth or position. The resistivity of soils is a complicated
function of porosity, permeability, ionic content of the pore fluids, and clay mineralisation.
Data are generally presented as profiles or contour maps and interpreted qualitatively.
Through resistivity profiling of the soils, one can detect map faults, map lateral extent of
conductive contaminant plumes, locate voids, map heavy metals soil contamination,
delineate disposal areas, map paleochannels, explore for sand and gravel, and map
archaeological sites.
Applications
Soil resistivity is used to detect changes in soil strata. Data analysis can be produced within
2 hours upon collection of data.
Once the data is collected, the data analysis can be produced within 2 h.
•
Subsurface mapping during project design
•
Interpolating between bore holes
•
Locating problem soil deposits (organics)
•
Sinkhole detection
•
Aggregate exploration
Advantages
•
Resistivity information can be used to determine where to take borings.
•
Readings can be obtained hundreds of feet deep.
•
Instrumentation is fairly inexpensive
•
Works well in conductive (clay) soils
•
Can look very deep (if needed)
•
Mobile systems under development
Limitations
•
Data analysis has to be verified by boring or sampling.
•
Different materials may have similar resistivity ranges.
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•
The setup is labor intensive and time-consuming. For a two-dimensional soil survey,
it usually takes three persons 1 day to collect data for a 1⁄2-mi length using 2-m
spacing between electrodes.
Speed
It usually takes three persons 1 day to collect a 1⁄2-mi length using a 2-m spacing
between electrodes for a two-dimensional soil survey. Data analysis can be
produced within 2 h.
Accuracy and Precision
The resolution is a function of the spacing between electrodes. For example, 2-m
spacing between electrodes produces about a 1-m accuracy. In terms of the
resistivity data, repeatability and reproducibility have been good as long as site
conditions have not changed and the equipment has been properly calibrated and
maintained.
Costs
AGI’s 56-electrode system is $45,000. Minnesota DOT purchased an AGI system
with underwater drag cables for $75,000. The cost includes data analysis software.
14.2 Hardware and software
14.2.1 Case one: soil resistivity testers
Examples: 3 and 4 pole earth resistance and soil resistivity testers (Chauvin Arnoux Group
2010) C.A 6460 & C.A 6462.
The C.A 6462 is tester designed for field-use. Housed in a sturdy, leak-proof case, it is
simply to set up and quick to use in order to deliver precise, reliable earth diagnosis.
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Fig.14-1 Soil resistivity testers C.A 6460 (Chauvin Arnoux Group 2010)
Ergonomics
•
Rugged, leakproof site case for use in the field
•
Large 2,000-count backlit LCD screen for easy reading
•
Digital display of the values measured and the units
•
Simple to operate
•
Instant connection thanks to colour-coding of the terminals and leads
Measurements
•
Earth resistance measurement with the 3 or 4-pole method and soil resistivity
measurement
•
Designed to reject high levels of noise and interference
•
Auto-ranging
•
3 warning LEDs:
-
high noise level,
-
high auxiliary stake resistance,
-
connection fault
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Power supply
•
Battery-powered (C.A 6460) or rechargeable battery (C.A 6462)
Table 14-1 Specifications and features for the soil resistivity testers (Chauvin Arnoux Group
2010)
Specifications
Measurements
Type
Measurement range
Resolution
Accuracy
No-load voltage
Frequency
Warnings
Other features
Power supply
Display
Electrical safety
Dimensions
Weight
C.A 6460
C.A 6462
Earth resistance / Soil
resistivity / Coupling
3-pole & 4-pole
0.01 Ω to 2,000 Ω
(3 automatic ranges))
10 m Ω / 100 m Ω/ 1 Ω
(depending on range)
± (2 % + 1 count)
24 V
128 Hz
3 fault-indication LEDs to
validate the measurement
Earth resistance / Soil
resistivity / Coupling
3-pole & 4-pole
0.01 Ω to 2,000 Ω
(3 automatic ranges))
10 m Ω/ 100 m Ω / 1 Ω
(depending on range)
± (2 % + 1 count)
48 V
128 Hz
3 fault-indication LEDs to
validate the measurement
8 x 1.5 V batteries
2,000-count digital LCD
IEC 61010 & IEC 61557
270 x 250 x 110 mm
2.8 kg
Rechargeable NiMH battery
2,000-count digital LCD
IEC 61010 & IEC 61557
270 x 250 x 110 mm
3.3 kg
C.A 6472 (Chauvin Arnoux Group 2010) is another example soil resistivity tester.
The C.A 6472 earth resistance and soil resistivity tester is a versatile instrument capable of
carrying out a quick but thorough survey of all the earthing configurations by combining all
the earth resistance measurement functions in a single tool.
Maintaining the same simple ergonomics as its predecessors, it is delivered in a rugged,
leakproof site case. In addition, when coupled with the C.A 6474, it can be used to measure
pylon earth resistances, making it an essential tool for diagnostics and maintenance of
earthing systems on all types of pylons.
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Ergonomics
•
Leakproof site case for use in the field
•
Large
backlit
LCD
screen
particularly legible multi-display
•
Simple to operate
•
Automatic recognition of connections
•
Instant connection thanks to colourcoding of the terminals and leads
•
Improved safety with
connections on the screen
•
USB communication interface
•
Compatible with the DataView® software
display
and
of
Fig.12-2 Soil resistivity testers C.A 6474
(Chauvin Arnoux Group 2010)
Power supply
•
Powered by rechargeable batteries
•
Adapters for battery charging on vehicle cigarette lighter or mains supply
Measurements
•
Earth resistance measurement by 3 or 4-pole method
•
Soil resistivity: automatic calculation (Wenner and Schlumberger methods)
•
Selective earth resistance measurement (4-pole measurement with clamp, loop
measurement with 2 clamps)
•
Measurement of ground potential according to the distance
•
Pylon earth resistance measurement (when used with C.A 6474)
•
Coupling measurement
•
200 mA continuity
•
Measurement frequency range from 41 to 5,078 Hz (automatic for the most
appropriate measurement frequency, as well as manual or sweep modes)
•
Measurement of auxiliary stake resistance
•
High rejection of disturbance voltages up to 60 V peak
•
Data storage
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Table 14-2 C.A 6472 Specifications (Chauvin Arnoux Group 2010)
Earth resistance Range
Measurements
Resolution
with 2 clamps
Measurement
frequency
Earth resistance Range (automatic
selection)
3-pole
Resolution
measurements
Test voltage
Measurement
frequency
Test current
Accuracy
Earth resistance Range
4P
Resolution
measurements/
4P
Test voltage
measurements
with clamps
Measurement
frequency
Test current
Accuracy
Measurement method
Soil resistivity
measurement
Range (automatic
selection)
– 4-pole method Resolution
Test voltage
Measurement
frequency
External voltage Range (automatic
selection)
measurement
Accuracy
Resistance
Type of measurement
measurement/
Range (automatic
selection)
continuity and
Accuracy
bounding
Test voltage
Test current
Data storage
Storage capacity
Communication
0.01 Ω to 500 Ω
0.01 Ω to 1 Ω
Auto: 1,367 Hz ; Manual: 128 Hz - 1,367 Hz 1,611 Hz - 1,758 Hz
0.01 Ω to 99.99 kΩ
0.01 Ω to 100 Ω
16 V or 32 Vrms rated voltage, selectable by
user
41 Hz to 5078 Hz automatic or manual
Up to 250 mA
±2 % R + 1 count at 128 Hz
0.001 Ω to 99.99 kΩ
0.001 Ω to 100 Ω
16 V or 32 V selectable
De 40 Hz to 512 Hz automatic or manual
Up to 250 mA
±2 % R ±1 count
Wenner or Schlumberger method with
automatic calculation of results and display in
Ω-metres or Ω-feet
0.01 Ω to 99.99 kΩ ; ρ max. 999 kΩm
0.01
to 100
16 or 32 V, selectable
41 to 512 Hz, selectable
0.1 to 65.0 VAC/DC – DC to 450 kHz
±2 % R + 1 count
2 wire and 4 wire method, selectable by user
2 wire: 0.01
to 99.9 k
– 4 wire: 0.001
to 99.99 k
±2 % R + 2 counts
16 Vdc (polarity +, - or auto)
> 200 mA for R < 20
512 test results
Optically-isolated USB
Other features:
•
Power supply: Rechargeable battery
•
Battery-charger power supply: External power supply with 18 Vdc / 1.9 A output or
12 Vdc vehicle power supply
•
Electrical safety: 50 V CAT IV
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•
Dimensions / Weight: 272 x 250 x 128 mm / 3.2 kg
Table 14-3 Test Accessories (Chauvin Arnoux Group 2010)
Composition
Earth resistance
Comprising 1 x 30 m green cable reel, 1 T-rod
1-pole loop kit
Earth resistance
50 m
Comprising 2 T-rods, 2 cable reels (50 m red, 50 m
blue), 1 cable winder (10 m green), 1 mallet, 5 spade lug
/ Ø 4 mm banana plug adapters, 1 carrying bag
3-pole earth kit
100 m Comprising 2 T-rods, 2 cable reels (100 m red, 100 m
blue), 1 cable winder (10 m green), 1 mallet, 5 spade lug
/ Ø 4 mm banana plug adapters, 1 carrying bag
150 m Comprising 2 T-rods, 2 cable reels (150 m red, 150 m
blue), 1 cable winder (10 m green), 1 mallet, 5 spade lug
/ Ø 4 mm banana plug adapters, 1 carrying bag
Earth and resistivity kit 100 m Comprising 4 T-rods, 4 cable reels (100 m red, 100 m
–
blue, 100 m green, 30 m black), 1 cable winder (10 m
green), 1 mallet, 5 spade lug / Ø 4 mm banana plug
adapters, 1 prestige carrying bag
4-pole
150 m Comprising 4 T-rods, 4 cable reels (150 m red, 150 m
blue, 150 m green, 30 m black), 1 cable winder (10 m
green), 1 mallet, 5 spade lug / Ø 4 mm banana plug
adapters, 1 prestige carrying bag
Resistivity add-on kit
100 m Comprising 2 cable reels (100 m green and 30 m black),
1 standard carrying case, 2 T-rods
C.A 647X continuity
Comprising 4 x 1.5 m cables terminated by Ø 4 mm
bound test kit
banana plugs, 4 crocodile clips, 2 test probes
(μΩ position)
Fig.14-3 Earth and resistivity kit: earth resistance and soil resistivity measurements using
any method (Prestige carrying bag) (Chauvin Arnoux Group 2010)
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Earth clamps: Each earth clamp is delivered in a carrying case with a 9 V battery and an
operating manual in 5 languages.
Table 14-4 Specifications of Earth clamps (Chauvin Arnoux Group 2010)
Earth resistance
Measurement
range
0.00 to 1.00 Ω
1.0 to 50.0 Ω
50.0 to 100.0 Ω
100 to 200 Ω
200 to 400 Ω
400 to 600 Ω
600 to 1,200 Ω
Measurement frequency
Current / leakage current (C.A
6412 & C.A 6415)
Current measurement frequency
Indication of disturbance currents
and incorrect closure
Alarm (C.A 6415)
Storage (C.A 6415)
Resolution
0.01 Ω
0.1 Ω
0.5 Ω
1Ω
5Ω
10 Ω
50 Ω
2403 Hz
1 to 299 mA
1 mA
0.300 to 2.999 A
0.001 A
3.00 to 29.99 A
0.01 A
47 to 800 Hz
By symbol displayed on LCD
±2 % ±2 counts
±1.5 % ±1 count
±2 % ±1 count
±3 % ±1 count
±6 % ±1 count
±10 % ±1 count
±25 % ±1 count
±2.5 % ±2 counts
±2.5 % ±2 counts
±2.5 % ±2 counts
User configurable
99 measurements
Other features
•
Power supply: 9 V battery
•
Display: 3,000-count LCD
•
Electrical safety: IEC 61010 - CAT III 150 V
•
Dimensions / Weight: 55 x 100 x 240 mm / 1 kg
Fig.14-4 Earth clamps (Chauvin Arnoux Group 2010)
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Software: Texas, Florida, and Minnesota DOTs used software developed by AGI that
comes with the equipment.
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15 Rebound Hammer Test
15.1 Introduction
The Rebound Hammer Test consists of a spring-controlled hammer mass which slides on a
plunger inside a tubular housing. The spring forces the hammer against the concrete test
surface, which may be at any angle, and the distance of rebound is measured on a scale.
Whatever the angle of the surface, the instrument must be calibrated against in the position.
Applications
A rebound (Swiss or Schmidt) hammer is a device used to measure the surface hardness
and penetration resistance of concrete or rock. The hammer can be used to measure the
elastic properties or strength of finished concrete structures as a result of its nondestructive nature.
Advantages
The rebound hammer can provide a fairly accurate estimate of concrete compressive
strength, with an accuracy of ±15 to ±20 per cent when specimens cast cured and tested
under conditions for which calibration curves have been established. In addition, it is
inexpensive, simple, and quick.
Limitations
Since the rebound hammer measures the surface hardness of the concrete, it is important
to understand all the items that might affect surface conditions of the concrete and thus, the
rebound hammer numbers. These factors include:
•
Smoothness of the surface
•
Size and shape of the concrete sample
•
The rigidity of the test area
•
Age of the concrete
•
Surface moisture
•
Internal moisture (moisture gradient)
•
Coarse aggregates
•
Type of cement
•
Forms used
•
Carbonation
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•
Location of the reinforcement
•
Frozen concrete
For these reasons, the user of the rebound hammer must follow exact procedures and use
engineering judgment.
15.2 Hardware and software
15.2.1 Case one: rebound hammer from Spectro Analytical Labs
Limited
The rebound hammer is an arbitrary scale ranging from 10 to 100. The hammers are
available from their original manufacturers in several different energy ranges. These
include: (i) Type L-0.735 Nm impact energy, (ii) Type N-2.207 Nm impact energy; and (iii)
Type M-29.43 Nm impact energy.
Fig.15-1 Rebound Hammer (Spectro Analytical Labs Limited 2013)
Table 15-1 Average Rebound number and quality of concrete (Spectro Analytical Labs
Limited 2013)
Average Rebound Number
>40
30 to 40
20 to 30
< 20
0
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Very good hard layer
Good layer
Fair
Poor concrete
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Procedure to determine strength of hardened concrete by rebound hammer (Spectro
Analytical Labs Limited 2013):
1. Before commencement of a test, the rebound hammer should be tested against the
test anvil, to get reliable results, for which the manufacturer of the rebound hammer
indicates the range of readings on the anvil suitable for different types of rebound
hammer.
2. Apply light pressure on the plunger - it will release it from the locked position and
allow it to extend to the ready position for the test.
3. Press the plunger against the surface of the concrete, keeping the instrument
perpendicular to the test surface. Apply a gradual increase in pressure until the
hammer impacts. (Do not touch the button while depressing the plunger. Press the
button after impact, in case it is not convenient to note the rebound reading in that
position.
4. Take the average of about 5 readings.
ASTM C805, Standard Test for Rebound Numbers of Hardened Concrete, provides some
standard procedures so that the user can have consistency when using the rebound
hammer.
Some of these standard procedures are:
•
Do not test frozen concrete.
•
The test area must be at least 150 mm (6 inches) in diameter and fixed rigidly within
the structure.
•
The surface to be tested must be flat with no loose mortar.
•
The surface to be tested must be free from water.
•
If the layer of carbonated concrete is thick, it should be removed before testing.
•
The hammer must be held in the same direction — horizontal, upward, downward
and it should always be at a right angle to the surface being tested.
•
Do not test over reinforcement with a cover of less than 20 mm (3/4 inch).
•
If estimating concrete strength takes at least two cores from six locations that have
different rebound hammer number.
•
Take 10 rebound hammer readings at each test area.
•
All individual readings should be at least 25 mm (1 inch) apart.
•
Discard any reading that is over six units from the average and calculate the
average of the remaining readings.
•
If two units are over six units from the average, discard the entire set of reading and
redo the test.
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15.2.2 Case two: James Digital Test Hammers
Fig.15-2 James Digital Test Hammers (James Instruments Inc. 2013)
Features of James Digital Test Hammers: Automatic calculation of mean rebound number,
compressive strength and more; Field Printer, PC connection and software for
downloading.
Table 15-2 Specifications of James Digital Test Hammers (James Instruments Inc. 2013)
Display:
2x16 Trans “ reflective
Construction:
All Aluminium for rugged construction environment
Operating Temperature:
0° to 50° C (32° to 122° F)
Batteries:
2 ˜AA™
Ap. Size:
100mm x 100mm x 270mm ( 4
Ap. Weight:
1.6 Kg (3.5 lbs.)
Printer Size:
64mm x 49mm x 31mm ( 2.5
Weight:
up to 0.270 kg ( 0.6 lbs ) with paper
Battery:
Internal Lithium ion with 1 yr. approximate life
Charger:
100VAC “ 240VAC 5 VDC 3.0A
Operating Temperature:
0° to 50° C (32° to 122° F)
Software
Windows PC Compatible / USB interface required
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x4
x 1.9
x 10
)
x 1.2
)
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16 Laser Scanning
16.1 Introduction
The laser scanning method uses the controlled steering of laser beams to perform a
distance measurement at every pointing direction. This method, often called 3D object
scanning or 3D laser scanning, is used to rapidly capture shapes of objects, buildings and
landscapes. The resulting data is acquired and generated with static survey accuracy, but
much faster and with much higher resolution. For instance, it can create (a) visual image of
the visible surface and its condition for crack detection; (b) thermal image of temperature
distribution for locate moisture and water intrusion; and (c) 3D recording of clearance for
detection of damages.
Fig. 16-1 Laser Scanning of Railway Tunnels (Cronvall unknown)
Applications
Laser scanning is an optical remote sensing technology. Its uses include finding the range
between sensor and target, and other property measurements such as the reflectance of
the target surface that corresponds to the magnitude of the backscattered laser energy.
The technique has numerous applications, including:
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
Monitoring movements and deformations of highway/railway infrastructure (tunnel
linings, retaining walls, bridge girders, etc.), and rock slopes,

Condition assessment and inspection of tunnels,

3-D mapping and modelling,

Aerial surveying,

Visualization,

Distance measurements, and

Characterization of aggregate characteristics.
Advantages

Captures “as is” conditions,

Creates 3-D models,

Attains 100% coverage, and

Allows continuous monitoring.
Limitations
The equipment collects data only for objects within the line of sight. Corrections for
atmospheric effects may be required as Laser range measurements can be influenced by
atmospheric conditions (air temperature and pressure).
Speed

The time needed to collect data with the method (i.e., the speed of testing) is less
than a minute to minutes, depending on point density and area of coverage.

Point clouds may be used immediately for visualization and distance
measurements. Post-processing modelling, CAD drawings, fitting, and so on are on
the order of weeks.
Accuracy and Precision
For most of the instruments that would be used for construction applications, the
manufacturer specifications vary from 5 to 10 mm. No standard method of verifying these
numbers exists. The FHWA NDE Centre used a system that had a reported accuracy of
0.0039 in. at 32.8 ft and 0.0094 in. at 78.7 ft. Repeatability and reproducibility are assumed
to be good.
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Costs
Most scanners cost between $100,000 and $150,000 and come with software for limited
modelling. Other, more sophisticated software ranges from $10,000 to $25,000 for annual
licenses. Service providers are available to assist with customer specific applications.
The FHWA Nondestructive Evaluation (NDE) Centre owns a scanner that costs
approximately $300,000.
16.2 Hardware and software
The hardware depends on the manufacturer but generally consists of a laser emitter, a
mirror system for deflecting the laser beam and collecting the backscattered laser light
cone, and electronics for data acquisition and processing.
Fig.16-1 Scan Point Density for railway Analysis Scanning (California Department of
Transportation 2011)
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16.2.1 Case one: Laser Scanning in USA
Fig.16-2 A laser scanning set (Wimsatt et al. 2008)
Fig.16-3 Typical Mobile terrestrial laser scanning (MTLS) Scanning Platforms (California
Department of Transportation 2011)
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Table 16-1 Stationary Terrestrial Laser Scanning Specifications (California Department of
Transportation 2011)
Operation/Specification
Initial calibration of instrument at startup and
during operation. Excessive vibration may render
the scanner inoperable
Level compensator should be turned ON unless
unusual situations (See Note 1) require that it be
turned OFF.
Minimum number of targeted control points
required.
STLS control and validation point surveyed
positional local accuracy.
Strength of figure: α is the angle between each
pair of adjacent control targets measured from
the scanner position.
Target placed at optimal distance to produce
desired results
Control targets scanned at high density
Measure instrument height (when occupying
control) and target heights
Fixed height targets (when occupying control)
Check position of instrument and targets over
occupied control points
Be aware of equipment limitations when used in
rain, fog, snow, smoke or blowing dust, or on wet
pavement.
Distance to object scanned not to exceed best
practices for laser scanner and conditions Equipment dependant
Distance to object scanned not to exceed
scanner capabilities to achieve required
accuracy and point density.
Observation point density
Overlapping adjacent scans (percentage of scan
distance)
Maximum measurement distance to meet
vertical accuracy standard for horizontal
(pavement) surface measurements
Minimum measurement distance
Registration of multiple scans in post-processing
Post-processing software registration error
report
Registration errors not to exceed in any
horizontal dimension
Registration errors not to exceed in vertical
dimension
Independent control validation points
(confidence measurements) to confirm
registration
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STLS Scan Application
Scan Type A
Scan Type B
Each set-up
Each set-up
2 for each set-up
H ≤ 0.03 foot
V ≤ 0.02 foot
Recommended
60º ≤ α ≤ 120º
H and V
≤ 0.10 foot
Recommended 40º ≤
α ≤ 140º
Each set-up
Required
Yes
Required
Recommended
Begin and end of each set-up
Each set-up
Manufacturer’s specification
Each set-up
Sufficient density to model object.
5% to 15%
260 feet
N/A
Manufacturer’s specification
Required
Required
0.03 foot
0.15 foot
0.02 foot
0.10 foot
Minimum of
three (3) per
scan
Minimum of two (2)
per scan
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Table 16-2 Mobile Terrestrial Laser Scanning Specifications (California Department of
Transportation 2011)
Operation/Specification
MTLS equipment must be capable of
collecting data at the intended accuracy and
precision for the project.
Initial calibration of MTLS system (per
manufacturers specs)
Dual-frequency GNSS recording data at 1
Hz or faster
Minimum IMU positioning data sampling
rate capability
Maximum IMU Gyro Rate Bias
Maximum IMU Angular Random Walk
(ARW)
Maximum IMU Gyro Rate Scale Factor
Minimum IMU uncorrected positioning
capability due to lost or degraded GNSS
signal
Maximum duration or distance travelled with
degraded or lost GNSS signal resulting in
uncorrected IMU positioning
Maximum uncorrected IMU X-Y positioning
drift error for 60 second duration or 0.6 mile
distance of GNSS outage
Maximum uncorrected IMU Z positioning
drift error for 60 second duration or 0.6 mile
distance of GNSS outage
Maximum uncorrected IMU roll and pitch
error/variation for 60 second duration or 0.6
mile distance of GNSS outage
Maximum uncorrected IMU true heading
error/variation for 60 second duration or 0.6
mile distance of GNSS outage
Project control should be the constraint for
GNSS positioning
Minimum order of accuracy for GNSS base
station horizontal (H) and vertical (V) project
control
MTLS Local Transformation Point and
Validation Point surveyed positional
accuracy requirements.
GNSS base stations located at each end of
project
Maximum post-processed baseline length
Maximum PDOP during MTLS data
acquisition
Continued
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MTLS Scan Application
Scan Type A
Required
Scan Type B
As Required
Required
100 Hz
1 degree per hour
0.125 degree per √hour
150 ppm
GNSS outage of 60 seconds or 0.6 miles
distance travelled
GNSS outage of 60 seconds or 0.6 miles
distance travelled
0.33 foot (0.100m)
0.23 foot (0.070m)
0.020_degrees RMS
0.020 degrees RMS
Yes
Horizontal – 2nd
Vertical – 3rd
H ≤ 0.03 foot
V ≤ 0.02 foot
H and V
≤ 0.10 foot
Recommended
Five (5) miles
Five (5)
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Table 16-2 Mobile Terrestrial Laser Scanning Specifications (California Department of
Transportation 2011) - Continued
Operation/Specification
Minimum number of common healthy
satellites in view for GNSS base stations
and mobile scanner
Minimum overlapping coverage between
adjacent runs
Monitor MTLS system operation for GNSS
reception
Monitor MTLS system operation for IMU
operation and distance and duration of any
uncorrected drift
Monitor MTLS laser scanner operation for
proper function
Monitor MTLS system vehicle speed
Minimum orbit ephemeris for kinematic
post-processing
Observations – sufficient point density to
model objects
Vehicle speed – limit to maintain required
point density
Filter data to exclude measurements
exceeding scanner range
Local transformation point maximum
stationing spacing throughout the project on
each side of scanned roadway
Validation point maximum stationing
spacing throughout the project on each side
of scanned roadway for QC purposes as
safety conditions permit.
MTLS Scan Application (See Section 15.8)
Scan Type A
Five (5)
Scan Type B
20% sidelap
Throughout each pass
Throughout each pass
Throughout each pass
Throughout each pass
Broadcast
Each pass
Each pass
Each pass
1500 foot intervals
2400 foot intervals
500 foot intervals
800 foot intervals
Software
Software comes with the unit, usually provided by the manufacturer.
16.2.2 Case two: track surface inspection systems
Features of track surface inspection systems from MERMEC Group include:

Track geometry, two technologies available (optical and inertial)

Rail profile and rail corrugation, from grinding to high speed application

Track vision systems, able to perform qualitative detection and dimensional analysis
of surface defects on the rail (e.g. 'head check') and inconsistencies in the ballast,
fasteners, sleepers and fishplates
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
Track video surveillance
Fig.16-4 V•CUBE has been engineered to integrate a track surface inspection system
(TSIS), track surface measurement system (TSMS) and track head-check inspection
system (THIS) into one small, easy platform. (MERMEC Group 2013)
Fig.16-5 (a) Scanner Configuration, (b) Track & Structure Inspection- AMV (MRX 2013)
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17 Conclusions
A survey on specifications of non-destructive test (NDT) methods for assessing railway
infrastructure has been carried out. This report summarises the benchmarking of the-stateof-art of the NDT methods in literature review. The present specifications may be
considered as experimental examples in the related subjects. And the data may provide as
references for design, development and analysis of a NDT instrument for the railway
infrastructure assessment. Through comparisons of applications, advantages and
disadvantages, costs, hardware and software, suitable methods may be seen to meet the
requirements and conditions of a user.
a) A railway infrastructure system is a complicated system with different materials’
layers, therefore there is no one single NDT method available to detect all kinds of
defects within the whole system. For instance, some NDT methods can be used in
rail assessment very well, but may not be suitable for other layer materials. Thus a
useful measurement device has to use multiple or/and hybrid NDT methods to
evaluate the track bed system.
b) Advanced technologies have been applied to rail transport, and great research and
development are still continuing in order to make railways more reliable, faster,
heavier, longer and greener. Some resources on NDT methods can be available
from NDT conferences and journals, as well as projects’ reports.
c) Various NDT methods have been developed in transport, some of which are
successfully used in railway; some are still on the development stage. A user should
choose suitable methods for the individual requirements and conditions.
d) Specifications of some NDT methods are available online, but some are not. Some
methods have national or international standards to follow, but some of them only
have company internal regulations. Specific specifications and products sometimes
are only suitable for some specific situations.
e) It would be helpful and beneficial to continuously “borrow” or merge with advanced
NDT technologies from other areas to railway infrastructure, such as from
aerospace industry and pavement industry.
f)
In development of NDT for railway infrastructure, advanced technologies and
specifications should be employed, in particularly for IT technologies and navigation
technologies.
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