Report 104190 Design of a Tractor for Optimised Safety and Fuel

Report 104190 Design of a Tractor for Optimised Safety and Fuel
Design of a Tractor for
Optimised Safety and Fuel
Consumption
Report 104190
Contents
3
Contents
1
Introduction.................................................................................................................... 6
2
Approach ....................................................................................................................... 7
3
State-of-the-Art Semi-trailer Trucks ............................................................................... 9
3.1
Body Shape of Trucks ............................................................................................. 9
3.2
Body Shape of Trailers .......................................................................................... 11
3.3
Close to Series Concept Trucks............................................................................. 12
3.4
Future Design Concept Trucks .............................................................................. 15
3.5
Key Learnings........................................................................................................ 20
4
Standards and Regulations.......................................................................................... 22
4.1
4.1.1
Vehicle Dimensions ............................................................................................ 24
4.1.2
Vehicle Masses .................................................................................................. 25
4.1.3
Passive Safety ................................................................................................... 27
4.1.3.1
External Projections .................................................................................... 27
4.1.3.2
Pendulum Tests .......................................................................................... 27
4.1.3.3
Front Underrun Protection Device ............................................................... 28
4.1.3.4
Lateral Protection ........................................................................................ 28
4.1.4
Towing Devices .................................................................................................. 29
4.1.5
Active Safety ...................................................................................................... 29
4.1.5.1
Direct Vision ................................................................................................ 29
4.1.5.2
Indirect Vision ............................................................................................. 30
4.1.5.3
Lighting Installation ..................................................................................... 32
4.2
Future Regulations ................................................................................................ 34
4.3
Key Learnings........................................................................................................ 36
5
6
Valid Regulations ................................................................................................... 23
Build-up of CAD Models .............................................................................................. 38
5.1
Definition of Reference Truck ................................................................................ 38
5.2
Optimised Base Concepts ..................................................................................... 40
Safety and Aerodynamic Concepts .............................................................................. 42
Contents
6.1
4
CFD Simulations .................................................................................................... 42
6.1.1
Aerodynamic Fundamentals ............................................................................... 42
6.1.2
CFD Simulations of the Reference Truck ........................................................... 46
6.1.3
CFD Simulations of the Optimised Base Concepts ............................................. 49
6.1.4
Selection of Concept for Additional Optimisation ................................................ 50
6.1.5
Advanced Concept ............................................................................................. 52
6.2
Wind Tunnel Tests ................................................................................................. 56
6.3
Crash Simulations.................................................................................................. 59
6.3.1
6.3.1.1
Definition of Functional Requirements ......................................................... 59
6.3.1.2
Concept Design .......................................................................................... 63
6.3.1.3
ECE-R 93 Test ............................................................................................ 66
6.3.2
Definition of Representative Crash Simulation Setups........................................ 67
6.3.2.1
HGV Accident Statistics .............................................................................. 67
6.3.2.2
Passenger Car Occupant Protection ........................................................... 73
6.3.2.3
VRU Protection ........................................................................................... 75
6.3.2.4
Self Protection............................................................................................. 76
6.3.3
7
Crash Management System ............................................................................... 59
Results of Crash Simulations ............................................................................. 78
6.3.3.1
Comparison of Partner Protection Performance .......................................... 78
6.3.3.2
Comparison of VRU Protection Performance .............................................. 84
6.3.3.3
Comparison of Self Protection Performance................................................ 85
Technical Assessment ................................................................................................. 89
7.1
Estimation of the Impact on Fatality Numbers in Europe ........................................ 93
7.2
Weight Investigation .............................................................................................. 95
7.3
Evaluation .............................................................................................................. 98
8
Environmental and Economic Assessment ................................................................ 100
8.1
Cost Estimation ................................................................................................... 103
8.2
Evaluation ............................................................................................................ 111
9
Recommendations ..................................................................................................... 113
9.1
Design Space ...................................................................................................... 113
Contents
5
9.2
Material Usage .................................................................................................... 115
9.3
Direct Vision ........................................................................................................ 115
10
Summary and Outlook ............................................................................................... 116
11
Formula Symbols and Indices.................................................................................... 118
12
Literature ................................................................................................................... 119
13
Appendix ................................................................................................................... 130
13.1
CFD Simulations .................................................................................................. 130
13.2
Partner Protection Simulations ............................................................................ 131
13.3
Frontal Collision without Offset ............................................................................ 131
13.4
Rear Shunt .......................................................................................................... 134
13.4.1
VRU Protection Simulations .......................................................................... 138
13.4.2
Reference Tractor: Central Impact ................................................................ 138
13.4.3
Reference Tractor: Edge Impact ................................................................... 141
13.4.4
Advanced Concept: Central Impact .............................................................. 143
13.4.5
Advanced Concept: Edge Impact.................................................................. 146
1
Introduction
1
Introduction
6
Current trucks are designed to carry a maximum of payload or a maximum volume of goods.
In European Union Regulations, the maximum weight and dimensions of trucks are clearly
restricted limiting the flexibility that is needed for safety or aerodynamic issues.
This study will analyse the benefits in terms of safety and CO2 emissions that would result
from an increase in the maximum semi-trailer tractor combination length (i. e. 40 t-HGV of
currently 16.5 m) without changing the maximum load length. Furthermore, the dimensions,
layout and design of such an optimised tractor will be determined. Simulations, calculations
and illustrations will support the achieved solution and recommendations will be derived.
The focus of the research project is to show the impact of a possible change in legislation
regarding the cabin length. The task is to develop an integrated cabin concept which is
focused on maximising environmental performance through aerodynamic streamlining and
optimising safety compared to an appropriate reference cabin. Utility and total cost of
ownership aspects set important boundaries. With regard to the internal consistence of the
project, the definition of both cabins including material use will be based around consumer
preferences. This approach guarantees comparability.
In the course of the safety optimisation and with regard to utility implications such as payload
requirements, the new cabin’s front structure properties will be designed to optimise impact energy absorption and simultaneously ensure a payload that reflects customer’s requirements. If the larger cabin is found to be heavier than the reference cabin, the report
will provide additional general lightweight design strategies for trucks to compensate.
In contrast to the APROSYS-project, which is described below in chapter 2.1, a significant
advantage in aerodynamic performance at a reasonable cabin length increase is one major
task of the study. As a starting point of the optimisations, the generic reference 40 t-HGV will
undergo aerodynamic optimisation. The most promising aerodynamic concepts will be set-up
in safety simulations, in which optimised passive and active safety performance will be
assessed and proven. In the course of the safety optimisation process the fully developed
deflecting front shape of the APROSYS-project will serve as a valuable basis. The
experiences can be used for the design of an aerodynamic and at the same time safer front
structure.
The final objective of the project is the concept development of a tractor unit for a 40 t-HGV
which is optimised for both safety performance and fuel consumption related to
aerodynamics making use of a variable tractor unit length without substantial increase of the
empty vehicle weight. The new tractor design will be assessed in a simulation environment
and also realised in a 1:18 hardware model for demonstration. The overall aim is to find out
how much length increase will prove to be the optimum for the best safety and environmental
performance and to create a basis to quantify fuel saving, emission reduction, reduction of
fatalities and serious injuries. Also the economic impacts will be analysed.
2
Approach
2
Approach
7
The first step is an overview of the state of the art concerning the body shape of trucks
carried out in chapter 3. This also includes the description of close to series and future
concept trucks. In addition, the most relevant valid and future regulations are described. On
these conditions a generic reference truck has to be defined in chapter 5.
As a starting point of the optimisations in chapter 6 the generic reference 40 t-HGV
undergoes an aerodynamic optimisation. The most promising aerodynamic concepts is setup in safety simulations in which optimised passive and active safety performance is
assessed and proven. In the course of the safety optimisation, and with regard to utility
implications such as payload requirements, the new front structure of the truck is designed to
optimise impact energy absorption and simultaneously ensure a payload that reflects
customer’s requirements. To evaluate the self-protection characteristics of the truck, it is
crashed against a semi-trailer block in finite elements (FE) simulation. The partner protection
characteristics are evaluated by the FE simulation of truck against passenger car
(compatibility) and VRU (vulnerable road users) protection simulations. In addition, the active
safety characteristics are evaluated concerning direct and indirect vision.
The detailed technical assessment of the optimised front structure is described in chapter 7
of the final report. Therefore the most relevant evaluation parameters are identified at first.
Afterwards, a new concept is evaluated for technical aspects. Analogous to that, the
environmental and economic impacts are analysed in chapter 8. Reduction of fuel
consumption, utility and total cost of ownership aspects set important boundaries. With
regard to the internal consistence of this study, the definition of both cabins including material
usage is based around consumer preferences. The results from aerodynamic simulation are
validated with wind tunnel tests in chapter 6.2.
A guideline for new development activities of the industry to introduce an optimised front
structure is given in the recommendations of chapter 9. This includes a detailed summary of
the effects on passive safety and fuel consumption as well as a priority list for changes of
current EU legal standards for cabin lengths. Also the influence on direct and indirect vision
is regarded.
The study concludes the results with a summary highlighting the main steps and giving an
outlook for possible future developments and further research potential. An overview of the
work packages of this study is shown in Fig. 2-1.
2
Approach
8
Step 1:
State of the art, constraints
and regulations
Step 2:
Simulation study
with optimisation
runs
WP3
Development of
safety and
aerodynamic
concepts
WP1
Research of
standards and
regulations
concerning
tractors
WP2
Model build-up of
tractor and semitrailer
WP4
Technical
assessment of
developed
concepts
WP5
Environmental
and economical
assessment
WP8
Documentation
Fig. 2-1:
Workflow of the study
Step 3:
Recommendations
and hardware
models
WP6
Derivation of
recommendations
WP7
Build-up of a
hardware
demonstrator
model and wind
tunnel test
3
State-of-the-Art Semi-trailer Trucks
3
State-of-the-Art Semi-trailer Trucks
9
In this chapter the general function of current body shapes for semi-trailer tractors is
described. Afterwards an overview of series and close to series concepts is given. Finally
future design concepts are described.
3.1
Body Shape of Trucks
The backbone of a tractor is the frame (Fig. 3-1). All other components, e.g. the cabin,
drivetrain, wheels, suspension, steering system and brakes are attached to the frame. The
cabin is constructed as a self-supporting unibody and should ensure sufficient survival space
for passengers. The cabin support absorbs energy in case of a crash. Especially semi-trailer
tractors have a high static load (Fstat) on their frame. This requires a complex balance
between stability, stiffness and mass. [BAC09, SCA10]
Sections of a tractor
Cabin
Static load on the frame
Suspension
Frame
Cabin support
Fig. 3-1:
Drivetrain
Fstat
Body shape of a tractor [BAC09, SCA10]
A large quantity of different requirements by the hauling companies result in a high flexibility
of the equipment of a tractor. This can be shown by the examples of the cabins in Fig. 3-2.
Most manufacturers offer a large range of different cabins. The height of the cabin can be
varied as well as the depth [DAF10, IVE07a, MAN09, DAI10a, REN10, SCA10, VOL10a].
Another vehicle that can be used as semi-trailer tractor for local distribution service is the
Mercedes-Benz Econic shown in Fig. 3-3. The cabin is made of an aluminium Spacecage®
covered by sheet moulding compound (SMC). Due to this the manufacturer claims a mass
reduction of the Econic cabin by 25 %. In addition two cabin heights are available and the
tractor shown in Fig. 3-4 is also available with natural-gas engine. Particularly advantageous
are the large side- and windscreens that enable a good visibility for the driver [DAI10b].
However, for long-distance transport this concept shows disadvantages. Because of the
package layout only small engines are available. The most powerful available engine for the
Mercedes-Benz Econic tractor version, for example, has 205 kW [DAI10b]. Regular long haul
vehicles come with engine power between 300 and 540 kW. Furthermore low-floor concepts
do not provide a hydraulic cabin support. Hence disadvantages regarding driving comfort
must be expected.
3
State-of-the-Art Semi-trailer Trucks
DAF XF
Iveco Stralis
Active
Day
Space
Cabin
10
Active
Time
MAN TGX
XL
Active Space³
Scania R-series
Medium Large low
Large
high
Fig. 3-2:
S
Active
Time
Super
Space Cabin
Renault Magnum
Large
XLX
XXL
Volvo FH
Medium
Large Longline
extra high
L, L low, L high Megaspace
Volvo FH 16
Medium high
Large
Large
M
Large high
Large high
Heavy duty truck cabs [IVE07a, MAN09, DAI10a, REN10, SCA10, VOL10a]
Spacecage®
Cabin types
Visibility
Fig. 3-3:
MB Actros
Mercedes-Benz Econic [DAI10b]
3
State-of-the-Art Semi-trailer Trucks
11
Tractor version
Fig. 3-4:
Tractor version of Mercedes-Benz Econic [DAI10b]
3.2
Body Shape of Trailers
Conventional HGV semi-trailers are available with one, two or three axles. The most
common semi-trailer is a three axle semi-trailer as shown in Fig. 3-5. These trailers are
available as board wall or as curtainsider. In general no special aerodynamic claddings are
used.
Conventional trailer
Fig. 3-5:
Krone Eco Liner
Trailer concepts [HOC10, KRO09]
Optimisation potential to reduce the fuel consumption of the complete truck does not only
exist in tractor design, but also in trailer design. A common technology is the application of
side fairings such as it is the case of the Krone Eco Liner. An accordingly equipped
articulated truck can have 5 % to 7 % lower fuel consumption because of reduced
aerodynamic drag [KRO09].
The UK trailer manufacturer Don-Bur offers an aerodynamically optimised trailer with a
curved roof, known as the “Teardrop Trailer”. First generation models were designed to
circulate on the domestic market exclusively which allowed for maximum heights strongly
exceeding four metres. Don Bur claims significantly reduced aerodynamic drag resulting in
important fuel economy improvements [DON10]. Recently Don Bur introduced a four metres
model designed for circulation on Continental European roads. The aerodynamic concept of
this trailer is compared with a UK standard trailer (4.2 m height) in Fig. 3-6.
3
State-of-the-Art Semi-trailer Trucks
British trailer (4.2 m height)
Fig. 3-6:
12
Teardrop trailer (4.7 m max. height)
Comparison of British trailer with Teardrop Trailer [DON10]
A similar concept to the Teardrop Trailer is the Cheetah from Cartwright. Through the
consequent application of aerodynamic covers, a curved roof and an open rear chassis, the
manufacturer claims that fuel savings of 16 to 18 % are possible (Fig. 3-7) [CAR10]. Another
example meeting legal dimensions for unlimited circulation within the EU territory is shown by
the so called 2WIN® trailers manufactured by the Dutch manufacturer Van Eck as well as
other according trailers form niche manufacturers Langenfeld and Spermann. The trailer
design contains two decks with a free loading height of 1.83 m. It is targeted to customers
that transport relatively light weight unstackable pallets with a height between 1.25 m and
1.80 m with regular matching return loads. The second deck increases the loading area more
than 50 % from 33 to over 50 Euro-pallets [EMO10].
Cartwright Cheetah
2WIN® Trailer
Fig. 3-7:
Cartwright Cheetah and 2WIN® trailer [CAR10, EMO10]
3.3
Close to Series Concept Trucks
One close to series concept is the prototype for the next generation of the Mercedes-Benz
Actros. First pilot production tractors are already tested on public roads. The tractor is
expected to have a new arrangement of daytime running lights, an intensive usage of
alternative powertrains and will be offered on market in 2011 [VER09]. Pictures of the first
prototypes show that the tractor has optimised aerodynamics, but no fundamental changes in
design.
3
State-of-the-Art Semi-trailer Trucks
Fig. 3-8:
13
Next generation of the Mercedes-Benz Actros [MOT11]
The concept truck of the Renault named Radiance was presented in 2004. It is illustrated in
Fig. 3-9. Numerous cameras mounted on aerodynamic supports allow visibility all around the
driving position. A steer-by-wire system without steering column improves crash
performance. The usage of active curve light further improves safety. The vehicle has
already been tested on public roads as well [LAS04].
Fig. 3-9:
Renault Radiance [LAS04]
A very detailed optimisation of a conventional truck is realised in the Iveco Transport
Concept shown in Fig. 3-10. Beneath optimised aerodynamics of the tractor, the vehicle has
a higher ground clearance and uses tires with a low rolling resistance. The trailer is the
Koegel Big-MAXX that is 1.3 m longer than a conventional semi-trailer. This increases the
load capacity and requires an exception permit for usage on public roads. The inflatable fins
on the cabin rear panel and rear end covering of the trailer reduce turbulences and improve
the aerodynamic drag. An additional improvement of aerodynamics is realised by underbody
covers. The manufacturer claims a fuel saving of 15 % in comparison to a conventional Iveco
Stralis truck resulting from all measures.
3
State-of-the-Art Semi-trailer Trucks
14
Fig. 3-10: Iveco Transport Concept [IVE07b]
A similar concept is realised by the Renault Optifuel Solution Generation 2010 concept. It
can be seen in Fig. 3-11. The truck is able to move 25 t of payload and consumes about 5 l
less fuel per 100 km. So the diesel consumption is reduced by 15 % as compared to a
conventional truck. The improved aerodynamics involves a front wraparound bumper that is
30 cm longer than in a conventional truck. The rearview mirrors are removed by a camerabased rearview system. The streamlined roof is raised to 4.16 m, so that it functions as a
deflector. The side fairing, underbody covering and 70 cm deflectors in the rear further
improve aerodynamics. In total 1 m is added to the overall vehicle length, leaving the payload
volume and mass unchanged [REN08].
Concept truck
Camera-based rearview system
Fig. 3-11: Renault Optifuel Solution Generation 2010 concept [REN08]
Due to stronger future regulations regarding fuel consumption and CO2-emissions and rising
requirements of customers, innovations in truck design will be necessary. One approach to
meet such requirements is to lower the truck’s weight. Volvo, for example, is developing a
“Super Light Heavy Truck” concept. Within this concept the manufacturer wants to achieve a
3
State-of-the-Art Semi-trailer Trucks
15
mass reduction of cabin and frame by 20 % in 10 years. The super-light cabin is designed in
FE simulation, using steel with reduced sheet thickness, aluminium and carbon fibre
reinforced plastics. The reduction of the total weight is realised without affecting other key
characteristics (e.g. crashworthiness or the ability to bear loads). The truck has the same
load capacity, but is powered by a smaller engine. To improve the sustainability, renewable
fuels or hybrid solutions are realised in which the diesel engine is jointly powering the electric
motor [VOL10b, HAR10].
Fig. 3-12: Cabin of the “Super Light Heavy Truck” [VOL10b]
3.4
Future Design Concept Trucks
The EC funded integrated project Advanced PROtection SYStems “APROSYS” is one of the
most important projects for this study because it is intended to start this project based on
these results. In the APROSYS project a safety concept for commercial vehicles which is
able to deflect a vulnerable road user (VRU: pedestrians and cyclists) sideways in case of an
accident by using the impact impulse was developed. The achieved deflection reduces the
risk of a run over. A tapered truck front has been designed and analysed that allows
additional deformation space for frontal collisions. Such a front shape can be realised by an
add-on structure mountable to the front or by a fully integrated concept as shown in
Fig. 3-13. In this project the integrated concept will be scaled to a 40 t-HGV truck.
Add-on structure
Fig. 3-13: Concepts of the APROSYS project [FAS08]
Integrated concept
3
State-of-the-Art Semi-trailer Trucks
16
During the development phase of the new front structure in APROSYS a large number of
design versions were generated and assessed. The resulting final principal shape was
compared to the basic truck in various numerical simulations with different accident
scenarios, pedestrian models and parameter settings. Due to the deflection principle, which
is used in the rounded front design for the weakest traffic participants, the structure
underneath can be designed mainly for protecting the heavy vehicle’s occupants and integrating partner protection relating to passenger vehicles (improved compatibility). The
deflection is not only a solution for the protection of pedestrians, but also reduces the impact
energy introduced into the heavy vehicle and the passenger car in a HGV-to-car-accident.
Such a convex truck front can significantly reduce the risk of a run over for VRU and also
deflect passenger cars. In addition, it provides a crush zone for energy absorption. The
enhanced passive safety could be shown in avoiding serious rollover accidents by 87.5 % of
the simulated cases in APROSYS [FAS08].
Another concept truck shown in Fig. 3-14 was presented at the IAA Commercial Vehicles
2002 in Hannover. The Aero Safety Truck is a semi-trailer tractor for long-distance transport.
The concept was developed in the innovation and design centre of the vehicle manufacturer
Hymer. The improved aerodynamics lead to a reduction in fuel consumption of up to
3 l/100 km. An improvement of safety is realised by an extremely stiff safety cage [LAS03,
HYM02].
Fig. 3-14: Aero Safety Truck [LAS03, HYM02]
The DAF Xtreme Future Concept (XFC), which can be seen in Fig. 3-15, was presented at
the IAA Commercial Vehicles in 2002. The improved aerodynamic concept reduces fuel
consumption and the danger of overrunning other road users by a deflecting frontend. The
cabin is designed to be based on an aluminium space frame [EAA02].
3
State-of-the-Art Semi-trailer Trucks
17
Fig. 3-15: DAF XFC [EAA02]
The Scania Concept illustrated in Fig. 3-16, was also presented on the IAA Commercial
Vehicles in 2002 as a bonnet truck concept for the future. The targets are to identify the
market interest for this concept and to optimise aerodynamics. In 2003 an additional concept
was presented with the Scania Crash Zone Concept. It has an added structure of 600 mm at
the front that absorbs more energy than that of a conventional truck. Therefore the survivable
collision speed rises from 56 to 90 km/h. It has potential to reduce the number of fatalities in
car to truck collisions. The extra weight for nose concept amounts to 250 kg [SCA02,
HAH03].
Scania STAX
Scania Crash Zone Concept
Fig. 3-16: Concept trucks by Scania [SCA02, HAH03]
In 2005 a demonstrator of the Colani Space Truck shown in Fig. 3-17 was presented. The
basis of this tractor is a Mercedes-Benz Actros. It is optimised for the usage with a silo semitrailer. With a cD value of 0.38 a reduction of fuel consumption of 30 % in comparison to its
reference is possible [NEW08].
3
State-of-the-Art Semi-trailer Trucks
18
Fig. 3-17: Colani Space Truck [NEW08]
Volvo presented the Volvo BeeVan Concept illustrated in Fig. 3-18 on the International Auto
Show in Detroit 2007. It is a concept for a heavy duty truck for the US market and took part in
the Michelin Challenge Design contest. The driver’s seat is in the centre of the cabin to
realise a full 180° visibility. Blind spot camera technology, lane tracking, parking sensors and
driver drowsiness sensors improve the active safety. The doors are slider operated and
hidden steps slide out automatically [AUT07].
Fig. 3-18: Volvo BeeVan Concept [AUT07]
In 2008 MAN presented the Bionic Truck with the body form of a dolphin shown in Fig. 3-19.
The design of the truck leads to a reduction of fuel consumption up to 25 % according to the
manufacturer’s declaration. Therefore the cabin needs to be lengthened by 70 cm and the
trailer by about 50 cm. So over all, the truck is 1.2 m longer than a conventional truck.
Furthermore comprehensive design changes are carried out at the tractor and at the trailer.
The trailer has a much rounder front shape. The trailer has a tear drop shape with a tapered
rear part and its wheels are covered. For these reasons the truck has a cD value of 0.29
[SCH08]. A further development of this study is the Concept S, which was exposed at the
IAA in 2010 as a hardware demonstrator as shown in the right image.
Fig. 3-19: MAN Bionic Truck and Concept S [SCH08]
3
State-of-the-Art Semi-trailer Trucks
19
The Scania Truck Concept shown in Fig. 3-20 was presented in 2009. It uses a hybrid
electric diesel drivetrain and has an ergonomic interior to provide a clean and liveable space
for the driver. The high-tech fenders show the duration the truck is travelling on the road as
information to other road users. Fig. 3-21 clarifies this. The optimised aerodynamics reduce
fuel consumption [PAL09].
Fig. 3-20: Scania Truck Concept [PAL09]
Green lights
Green and red lights
Driving < 7 h in a 24 h period
and driving < 4 h since last 45 min break
Driving < 7 h in a 24 h period,
but driving > 4.5 h since last 45 min break
Red lights
Flashing red lights
Driving longer than 9 h in 24 h period
Truck travelling faster
than allowed on this kind of road
Fig. 3-21: Fenders of the Scania Truck Concept [PAL09]
Recently Magna presented the Eco Truck shown in Fig. 3-22 with an aerodynamic design
and a lightweight heavy truck frame. The tractor is using a frame in “Monocoque Design“ and
is designed for the European market. By the usage of welded sheet metal and a casted
3
State-of-the-Art Semi-trailer Trucks
20
frame head, a weight reduction of 290 kg (34 %) in comparison to a conventional frame has
been realised. Beneath a good space utilisation by the integration of components (e.g. tank)
in the frame, the design qualifies the tractor for the usage of alternative drivetrains. In
addition it is suitable for future safety requirements and has a high stiffness [WIN10].
Fig. 3-22: Magna Eco Truck – lightweight heavy truck frame [WIN10, WOL10]
3.5
Key Learnings
Today all trucks have a similar design. The backbone of the tractor is the frame on which the
cabin, all drivetrain parts and the suspension parts are mounted. The cabin is executed as a
self-supporting unibody construction. The analysis of close to series trucks shows there will
be no fundamental changes of the flat front design of tractors within the next few years.
Important components that can be found on regular 40 t tractors are shown in Fig. 3-23. The
optimisation of aerodynamics, passive safety and lightweight design are the most important
development fields on the truck body. These components are considered in the generic
reference model that is used as the basis for the optimisations in this study.
3
State-of-the-Art Semi-trailer Trucks
Screens
21
Roof spoiler
Large standard
cabin
Side spoilers
Mirrors
Air inlets
5th wheel
Engine
Frame
Front cover
Tanks
Chassis
Drivetrain
Side covers
Fig. 3-23: Components of a 40 t-HGV tractor
In future the flexible integration of different drivetrain concepts will gain increased efficiency.
Design studies with increased tractor length show clear advantages on aerodynamics.
Additionally, improvements of active and passive safety are realised in some concept trucks.
Some of the ideas shown in this chapter will be adapted for the design of the new front
structure.
4
Standards and Regulations
22
4
Standards and Regulations
The important Directives and Regulations released by the European Union that affect the
design, the environmental and the safety performance of 40 t trucks are summarised in
Fig. 4-1 to Fig. 4-4. The most important Directives and Regulations for this study are marked
with an “!”.
Environment
99/99/EC
Engine power
2003/76/EC
Emissions
2006/81/EC
Diesel emissions
2007/34/EC
Sound levels
595/2009/EC
Emissions (EURO VI)
Fig. 4-1:
Important Directives and Regulations for trucks concerning environment
Passive Safety
89/297/EEC & ECE-R 73
Lateral protection (!)
91/226/EEC
Spray suppression systems
92/114/EEC
External projection of cabs (!)
2000/40/EC & ECE-R 93
Front underrun protection (!)
2001/31/EC
Door latches and hinges
2001/92/EC
Safety glazing
2004/11/EC
Speed limiters
2005/39/EC
Seat strength
2005/40/EC
Safety belts
2005/41/EC
Safety belt anchorage
2006/20/EC
Fuel tank
661/2009/EC
General safety (!)
ECE-R 29
Pendulum tests (!)
Fig. 4-2:
Important Directives and Regulations for trucks concerning passive safety
4
Standards and Regulations
23
Active Safety
70/387/EC
Doors
70/388/EC
Audible warning
94/53/EC
Identification controls
95/56/EC
Antitheft
97/39/EC
Speedometer and reverse gear
99/7/EC
Steering effort
2002/78/EC
Braking
2005/11/EC
Tyres
2005/27/EC
Indirect vision (!)
2008/89/EC & ECE-R 48
Lighting installation (!)
Fig. 4-3:
Important Directives and Regulations for trucks concerning active safety
Other directives
70/222/EC
Rear registration plate
78/507/EC
Statutory plates
94/20/EC
Mechanical couplings
96/64/EC
Towing hooks
98/91/EEC
Vehicles for transport of dangerous goods
2003/19/EC & 96/53/EC
Masses & dimensions (!)
2006/119/EC
Heating systems
2009/19/EC
Interference suppression
Fig. 4-4:
Other important Directives and Regulations for trucks
Because the rear wall of the cabin in the optimised concept of this study is not changed in
comparison to the reference cabin, only the front impact is of interest.
4.1
Valid Regulations
This chapter provides an overview of the important regulations affecting the design and
dimensions of European Heavy Goods Vehicles. It includes those regulations that concern
the frontal tractor structure and prescribe aerodynamics implications.
The optimised cabin design concept is subsequently built up in a way that ensures
compliance with all of the below regulations, except for the provisions concerning maximum
authorised vehicle length in national and international traffic as set out in the current version
of 96/53/EC.
4
4.1.1
Standards and Regulations
24
Vehicle Dimensions
A unified European Regulation was introduced in 1984. Before 1984 all European countries
had their own regulations. In the context of the implementation of a common road freight,
European transport market harmonised maximum vehicle lengths for all transport affecting
international competition were first introduced in 1984. The total length for tractor semi-trailer
combinations was set to 15.5 m (85/3/EWG).
In 1990 the maximum total length of semi-trailer trucks increased to 16.5 m (89/461/EEC).
This length limit was adopted in 1996 with directive 96/53/EC. The target was to allow for
sufficient productivity of vehicle combinations and to improve the driver’s space. To this end, the maximum length of a semi-trailer was limited to 13.6 m and the maximum distance
between the king pin and frontend of the semi-trailer to 2.04 m. The maximum authorized
vehicle length in national and international traffic as set out in this directive is still valid today.
In 96/53/EC provisions are set out to Member States that allow an extension of the maximum
length for vehicles that circulate on their territory. The directive stipulates that member states
may only grant such allowances under strict conditions. National circulation may for instance
not affect the functioning of the common EU road freight transport market.
European vehicle width for standard vehicles is limited to a maximum of 2.55 m with only
Finland and the Ukraine allowing for larger vehicles for national transport that does not affect
European competition. For refrigerated transports in Europe the general limit is 2.60 m.
Maximum vehicle height for free circulation across Europe is set at 4 m. One example of
where a member state allows for the circulation of vehicles that deviate from this limit is the
UK. In the UK national transport that does not affect international competition, is not height
limited. The default high roof trailer height has become 16’’ (4.88 m) which allows for the
circulation across the country without facing significant infrastructure boundaries on primary
roads.
European HGV type approval legislation 97/27/EC, that governs the approval for new vehicle
types, cross references the maximum dimensions of the circulation directive 96/53/EC. In
other words: No Member States may refuse to issue European type approval to a new
vehicle on the grounds of vehicle dimensions aspects, if that vehicle complies with the
maximum dimensions as set out in 96/53/EC.
Member states may also issue type approval to longer, higher or larger vehicles – however
their subsequent circulation is then subject to the above mentioned limitations and any
Member State may refuse to accept the approval on his territory.
4
Standards and Regulations
25
Important points are:



Whereas 96/53/EC entails maximum dimensions of whole vehicle combinations,
97/27/EC governs each of the vehicles separately.
Whenever the above conditions regarding circulation are not met, vehicles may only
circulate on a national basis provided certain conditions are fulfilled.
Vehicles exceeding the dimensions in 96/53/EC may not circulate internationally.
This study will optimise a standard tractor-trailer combination that is eligible receive type
approval and to freely circulate across Europe. The most important maximum dimensions for
such a combinations are shown in Fig. 4-5 [HOE06b, EEC89, ECX96]. They form the
reference for the design concept.
≤ 12 m ≤ 4 m ≤ 2.04 m ≈ 13.6 m ≤ 16.5 m Fig. 4-5:
≤ 2.55 m Lengths guideline for European tractor/trailer combinations (96/53/EC)
The provisions indirectly result in a limited design space for European tractor manufacturers
that offer tractors for the European general cargo market. This market, which constitutes a
big share of heavy goods vehicle transport in Europe typically, features semi trailers that
exploit maximal trailer dimensions. This leaves less than 2.5 m between the forward most
part of the trailer and the front end of the tractor. This constraint is indirectly regulated as the
difference between the maximum total vehicle length (16.50 m) and the maximum trailer
length (~ 14.05 m). The resulting length defines the dimensions for tractor unit design in
Europe.
The current implicit cabin length limits imposed by directive 96/53/EC result in blunt front
cab-over-engine designs, which have disadvantages regarding aerodynamics and safety.
4.1.2
Vehicle Masses
The maximum laden weight of Heavy Goods Vehicles in international transport 96/53/EC is
also governed by 96/53/EC. In general terms, cross border circulation of semi-trailer trucks is
limited to a maximum of 40 t. For national transport and in combined transport operations
with 40’ ISO containers, the laden weight may deviate from this maximum weight, provided axle load requirements are met.
4
Standards and Regulations
26
The load on a single axle of a tractor must be lower than 10 t, a double axle lower than 11.5 t
to 19 t, depending on the wheel base. The load on the drive axle of the tractor is limited to
11.5 t. The single axle load of a trailer is limited to 10 t, a double axle load to 11 t to 20 t and
a triple axle load to 21 t to 24 t, depending on the axle spacing of the trailer [ECX96].
For combinations made up of a two axle tractor and a three axle trailer this results in a 40 t
weight limit – being the most common configuration on European roads. 44 t vehicles must
have a three-axle tractor in order to distribute the weight in accordance with the provisions.
Four axle articulated vehicle combinations have a total weight limit of 36 t. If the distance
between the axles of the semi trailer is more than 1.8 m a margin of 2 t can be permitted
[ECX96]. Fig. 4-6 provides an overview of the possible combinations.
44 t
40 t
36 t (+2 t)
Fig. 4-6:
Weight limits for semi-trailer trucks [ECX96]
Turning cycle requirements are governed by Directive 97/27/EC. Every vehicle and every
vehicle combination has to be able to turn in a circle with an outer radius of 12.5 m and an
inner radius of 5.3 m (Fig. 4-7). When the vehicle moves forward on either side following the
circle of 12.5 m radius, no part of it may protrude the vertical plane by more than 0.8 m
[ECX03].
R = 12.5 m
r = 5.3 m
U ≤ 0.8 m
U
r
R
Fig. 4-7:
Turning cycle requirements [ECX03]
4
Standards and Regulations
4.1.3
27
Passive Safety
This chapter describes important regulated passive safety requirements. This includes
requirements on external projections as well as test regulations and protection devices.
4.1.3.1
External Projections
The general requirements for external projections of Heavy Goods Vehicles are described in
92/114/EEC. It determines that no external surface of the vehicle may exhibit a part likely to
catch or injure pedestrians, cyclists or motor cyclists. It mandates usage of rounded edges to
decrease the likelihood of injuries (radius ≥ 2.5 mm). Frontal protective devices must have a
radius of ≥ 5 mm. Parts of grilles must exhibit a radius of curvature of not less than 2.5 mm if
the distance between adjacent parts is more than 40 mm. If the distance is between 25 and
40 mm, the radius must not be less than 1 mm and if the distance is less than 25 mm, the
radius must not be less than 0.5 mm. The protrusion of handles, hinges, pushbuttons of
doors, luggage compartments, bonnets, vents, access flaps and grab handles must be
≤ 50 mm (≤ 30 mm for pushbuttons, ≤ 70 mm for grab handles). All edges of lateral air and
rain deflectors must have a radius of curvature ≥ 1 mm and sheet metal must not be touched
by a sphere of 100 mm diameter or is provided with a protective covering having a radius of
curvature ≥ 2.5 mm.
4.1.3.2
Pendulum Tests
The standards for pendulum tests on truck cabins are set out by ECE-R 29. These are
explained in Fig. 4-8. The target is to enable enough space for the occupants without contact
with rigid elements of the cabin after a collision. A minimum survival space has to be
provided for every seat. In the front impact test, the impact energy for a total permissible
weight ≤ 7 t is 2900 mdaN. For a total permissible weight ≥ 7 t it is 4400 mdaN. In the roof
strength test, the load P is the maximum permitted weight for the front axle with a maximum
weight of 10 t. The load P of the rear-wall strength tests amounts to 200 kg per ton of
permitted payload [ECE93].
Front impact
Roof strength
Rear-wall strength
P
P
Fig. 4-8:
Pendulum tests for cabins (ECE-R 29) [ECE93, DAF10]
4
Standards and Regulations
4.1.3.3
28
Front Underrun Protection Device
An important body component for a frontal crash (e.g. against a passenger car) is the front
underrun protection device (FUPD). ECE-R 93 describes the requirements for this
component.
The section height of the FUPD cross-member should be ≥ 120 mm. The lateral extremities
of the cross-member shall not bend to the front or have a sharp outer edge (rounded outside
and a radius of curvature ≥ 2.5 mm). The outermost surfaces of every front guard installation
shall be essentially smooth or horizontally corrugated save that domes heads of bolts or
rivets may protrude beyond the surface to a distance not exceeding 10 mm [ECE94]. Other
important measurements and requirements of FUPD are shown in Fig. 4-9.
Side view
Plan view
Vehicle front
700-1200
P1
After test
P2
P3
P2
200
Minimum
guard width
100
Maximum
guard width
Points P
Max. 400 mm Max. 450 mm
after test
after test
Mudguard
Max. 445 mm
as installed
Fig. 4-9:
Front underrun protection device [ECE94, DAF10]
4.1.3.4
Lateral Protection
All trucks must have an effective lateral protection in form of a special lateral protective
device or special components that complies with the requirements. That means components
permanently fixed to the vehicle, e.g. spare wheels, battery box, air tanks, fuel tanks, lamps,
reflectors and tool boxes may be incorporated in a sideguard. Additionally they must meet
the dimensional requirements of this regulation. The lateral protective device shall not
increase the overall width of the vehicle. Its forward end should be turned inwards and the
outer surface of the device shall be smooth, as far as possible continuous from front to rear.
All external edges and corners with a radius ≥ 2.5 mm and the device may consist of a
continuous flat surface or rails or a combination of both. The distance between the rails shall
not exceed 25 mm and measure at least 25 mm of height. The longitudinal position shall be
≤ 300 mm rearward to the outer surface of the next tire. The edge shall consist of a
4
Standards and Regulations
29
continuous vertical member extending the whole height of the guard. The lower edge of the
sideguard should be ≤ 550 mm above the ground and the upper edge of the guard shall not
be more than 350 mm below that part of the structure of the vehicle. Sideguards shall be
essentially rigid, securely mounted and made of metal or any other suitable material.
Because they are not relevant for frontal crash, the requirements are not described in detail.
Further information can be found in ECE-R 73 [ECE88].
4.1.4
Towing Devices
All motor vehicles must have a special towing-device that is fitted at the front. To this towing
device a connecting part, such as a towing-bar or tow-rope, may be fitted. Each special
towing-device fitted to the vehicle must be able to withstand a tractive and compressive static
force of at least half the authorised total weight of the vehicle, only without the towed load to
which it is fitted [EEC77].
4.1.5
Active Safety
A number of active safety requirements concerning indirect vision and lighting installation are
important for this study.
4.1.5.1
Direct Vision
European trucks’ minimum direct field of vision is not regulated. Regulation ECE-R 125,
relating to direct field of vision, only applies to passenger cars (vehicles of category M1).
Notably due to the high seating position of the driver the downward vision shall be adequate
to allow the driver to recognise pedestrians walking in front or besides of the cab. The
downward vision is illustrated in Fig. 4-10.
Fig. 4-10: Downward vision of trucks
4
Standards and Regulations
4.1.5.2
30
Indirect Vision
An important aspect of active safety on large vehicles is indirect vision as shown in Fig. 4-11.
Class V
Class IV
Class II
Danger zone
Fig. 4-11: Field of vision requirements 71/127/EEC [MEK10]
The requirements of indirect vision devices for new vehicles are set out by 2003/97/EC
(Fig. 4-12). It repealed 71/156/EC and strengthened the requirements.
The vision on the passenger’s side and on the driver’s side is ensured by mandatory Class II
and Class IV mirrors on both sides. A close-proximity mirror (class V) on the passenger side
is compulsory. It must be fixed at least 2 m above the ground. A class V mirror on the driver
side can be used as an option. The first-time prescribed front mirror (class VI) enables the
driver to see the area directly in front of the vehicle to improve the visibility of pedestrians
and cyclists. As a result the danger zone can now be seen indirectly by the driver.
4
Standards and Regulations
31
Class V
Class IV
Class VI
Class II
Danger zone
Fig. 4-12: Field of vision requirements 2003/97/EC [MEK10]
Following the adoption of 2003/97/EC the European Commission has mandated stricter
requirements of existing vehicles through the adoption of 2007/38/EC which governs
retrofitting requirements of indirect vision devices. This has improved the safety level across
the fleet.
The differences in the field of vision between 71/127/EEC and 2003/97/EC for class IV and
class V mirrors are shown in Fig. 4-13.
Comparison of field of vision requirements for class IV mirrors
71/127/EEC
= 215 m²
2003/97/EC
= 308 m²
Difference
= 93 m²
Comparison of field of vision requirements for class V mirrors
71/127/EEC = 2.25 m²
2003/97/EC = 5.5 m²
Fig. 4-13: Field of vision requirements 2007/38/EC [DOD09]
Difference = 3.25 m²
4
Standards and Regulations
32
With the fulfilment of directive 2003/97/EC about one third of the potential blind spots can be
eliminated. An additional elimination of blind spots is possible with the usage of supplementary devices like the ones shown in Fig. 4-14. Using a Fresnel lens, an elimination of 78
to 90 % of the blind spots is possible. The optimum position on the passenger side is the
bottom of the window. A retrofitting of trucks with this lens is possible, but also an
implementation to a laminated screen of new trucks is feasible [DOD09].
BDS mirror
Fresnel lens
Dobli mirror
Fig. 4-14: Supplementary devices to reduce blind spots [DOD09]
An alternative solution is using curvature mirrors like a Dobli mirror or a BDS mirror. The BDS
mirror eliminates 37 to 75 % of the blind spots and the Dobli mirror 43 to 76 %. Both fulfil the
directive 2003/97/EC for class IV and class V mirrors but are difficult to adjust without special
ground markings. But they do not fulfil the requirements for the indirect field of vision for all
ocular points.
4.1.5.3
Lighting Installation
Another important regulation for active safety is ECE-R 48 that governs the lighting
installations of all road vehicles. The positions of the different lamps are shown in Fig. 4-15.
The most important lamps for driving at night are the headlamps (Fig. 4-15, position 1). Two
or four main-beam headlamps are mandatory for trucks > 12 t. The headlamps must not
cause any discomfort to the driver either directly or indirectly through mirrors or reflecting
surfaces of the vehicle. If four headlamps are used, only one per side is allowed to be used
for bending light. The headlamps have to ensure a conical illumination (≤ 5°) of the forefield
[ECE08].
Also beneath the main-beam headlamps, two dipped-beam headlamps (Fig. 4-15, position 2)
are mandatory. Their position is described in ECE-R 48. The edge of the apparent surface in
the direction of the reference axis, which is farthest from the vehicle's middle plane, shall not
be more than 400 mm from the extreme outer edge of the vehicle. The inner edges of the
apparent surfaces in the direction of the reference axes shall not be less than 600 mm apart.
The height should be between 500 mm and 1200 mm above the ground level. In addition no
discomfort to the driver either directly or indirectly through mirrors or reflecting surfaces of the
vehicle is allowed to occur. The allowed lighting angle are 15° upwards and 10° downwards
as well as 45° outwards and 10° inwards [ECE08].
4
Standards and Regulations
33
rear
front
≥ 600 mm ≤ 400 mm
Fig. 4-15: Position of lighting installation [ECE08]
Front fog lamps (Fig. 4-15, position 3) are optional on motor vehicles. The edge of the
apparent surface in the direction of the reference axis, which is farthest from the vehicle's
middle plane, shall be not more than 400 mm from the extreme outer edge of the vehicle.
Their position in height is established between 500 mm and the maximum height of the
vehicle. Analogous to the other front lamps, no discomfort to the driver either directly or
indirectly through mirrors or reflecting surfaces of the vehicle is allowed to occur. The allowed
lighting angle are 5° upwards and downwards as well as 45° outwards and 10° inwards
[ECE08].
Direction indicator lamps (Fig. 4-15, position 5 and 7) are mandatory for all vehicles. Different
categories of lamps are used. Category 1, 1a and 1b are front direction indicator lamps,
category 2a and 2b are rear direction indicator lamps, category 5 and 6 are side direction
indicator lamps. A description of their illumination angles is shown in Fig. 4-16. The edge of
the apparent surface in the direction of the reference axis which is farthest from the vehicle's
middle plane shall be not more than 400 mm from the extreme outer edge of the vehicle. The
inner edges of the apparent surfaces in the direction of the reference axes shall be not less
than 600 mm apart. The height above ground level is between 500 mm and 1500 mm for
category 5 and 6 lamps. Category 1, 1a, 1b, 2a and 2b have to be arranged between
350 mm and 1500 mm in height. Optional direction indicator lamps have to be fixed more
than 600 mm above the mandatory lamps. The side direction indicator lamps must be fixed
less than 1800 mm behind the front direction indicator lamps [ECE08].
4
Standards and Regulations
34
Fig. 4-16: Illumination angles of indicator lamps [ECE08]
In the rear part of a vehicle, two rear position lamps (Fig. 4-15, position 9) are mandatory for
all vehicles. The edge of the apparent surface in the direction of the reference axis which is
farthest from the vehicle's middle plane shall not be more than 400 mm from the extreme
outer edge of the vehicle. The inner edges of the apparent surfaces in the direction of the
reference axes shall not be less than 600 mm apart. The height should be between 350 mm
and 1500 mm above ground. The allowed lighting angle are 45° inwards and 80° outwards
as well as 15° above and below the horizontal plane [ECE08].
In addition to these lamps, all vehicles exceeding 2.1 m in width must have end-outline
parking lamps. Two of them must be fixed in the front and two in the rear of the vehicle.
These lamps must be attached ≤ 400 mm from the outer edge of the vehicle. They must have
a lighting angle of 80° outwards, 5° above and 20° below the horizontal plane [ECE08].
Also two front and two side reflector lamps are mandatory for all vehicles exceeding 2.1 m in
width. These lamps are also attached in an area less than 400 mm from the outer edge of
the vehicle. Their position in height is between 250 and 900 mm above ground level and they
shall have a lighting angle of 30° inwards and outwards as well as 10° above and below the
horizontal plane [ECE08].
4.2
Future Regulations
The General Safety Regulation 661/2009/EC announces the repeal of directives that were
identified as vital in the context of this study, namely on indirect vision and type approval.
Indirect vision requirements will be globally harmonised. The commission has already
aligned legislation with existing UNECE regulations on these issues. 97/27/EC will be
converted into a directly applicable European regulation. This will likely happen in
comitology. Work has started concerning weights and dimensions. Whereas an extension of
aerodynamic devices from measurement might be added to the future type approval
regulation, this would not allow for longer integrated cabin designs since devices are
detachable.
4
Standards and Regulations
35
To identify more future regulations, the latest global technical regulations (GTRs), proposals
for GTRs and candidates for GTRs are analysed for relevance. For GTRs and candidates for
GTRs no relevant regulations for heavy trucks have been identified.
On the one hand this is a proposal to develop a regulation concerning the common
definitions of vehicle categories, masses and dimensions (TRANS/WP.29/AC.3/11). The
target is to harmonise the commonly given definitions of the category, mass and dimensions
of vehicles in all GTRs to help the contracting parties in establishing and adopting GTRs.
On the other side this is a proposal to develop a global technical regulation concerning
vehicles with regard to the installation of lighting and light-signalling devices
(TRANS/WP.29/AC.3/4). This proposal has several targets. One target is to harmonise the
regulation on installation of lighting and light-signalling. This should have positive effects on
the safety of the travelling public worldwide. Light signalling devices should convey a simple,
understandable message. In addition this should lead to a cost reduction of vehicle design
and production costs for manufacturers. It would be possible for a manufacturer to design,
stamp or mould one set of body panels for a vehicle model if a harmonised GTR would exist.
The consumer would benefit by having better choice of vehicle lighting built to better, globally
recognized regulations providing a better level of safety and at lower price [TRA05, TRA03].
In addition working documents of different working parties of the last years have been
analysed. These are GRSP (Working Party on Passive Safety), GRSG (Working Party on
General Safety Provisions), GRE (Working Party on Lighting and Light-Signalling) and GRPE
(Working Party on Pollution and Energy). In the GRSG one relevant document has been
identified that is a proposal for amendments to devices for indirect vision (ECE/TRANS/
WP.29/GRSG/2010/9). The target is to reduce side-swipe incidents when large vehicles are
changing lanes on motorways by providing a better visibility for the driver. This should result
in an enlargement of the visible area in the side of the truck as described in Fig. 4-17. The
visibility can be realised by direct vision or via indirect vision by using devices.
Fig. 4-17: Improvement of direct and indirect visibility for lane changing [GRS10]
4
Standards and Regulations
36
An outlook on future active safety systems that could become mandatory for new trucks is
described in the directive 661/2009/EC. In this direction national authorities are advised to
refuse new vehicles without an electronic stability control system starting in 2011. More than
that this directives advised the commission to assess advanced emergency braking systems,
lane departure warning system and tyre pressure monitoring systems to become a
mandatory installation in future [ECX09].
4.3
Key Learnings
Requirements that result from Directives and Regulations are summarised in Fig. 4-18. This
figure includes the Directives and Regulations that are important for this study.
The most constraining regulation in this study is the length limitation by 96/53/EC. This
regulation obstructs improvements of passive safety and aerodynamics. In the past an
adaptation of the length has been realised to improve road safety, for environmental reasons
or to improve rentability. The same reasons are discussed in this study to increase maximum
total length with the important condition of unchanged loading lengths. Changes of the front
structure will also result in changes of the axle load. Clearly existing axle load provisions
have to be fulfilled.
The most important requirements on passive safety are described in 92/114/EEC. In addition
the requirements on front underrun protection devices are described in ECE-R 93. Apart from
these regulations, also the requirements on active safety concerning indirect vision
(2003/97/EC) and lighting installation (ECE-R 48) have to be fulfilled by the new concept.
Pendulum tests as described in ECE-R 29 will be substituted by crash tests in this study (see
chapter 6.3).
Indirect vision
through mirrors
Limited total length (tractor and
trailer)
Limited total
height
Sufficient field
of direct view
Crash performance
of the cabin
Limited total mass
(tractor and trailer)
Functional areas
for headlamps
Lateral protection devices
Towing device
Front underrun
protection device
(underneath the
front covering)
Radii of edges > 2.5 mm
Limited axle loads
Limited total
width
Radii of front protection devices > 5 mm
(e.g. for pedestrian protection)
Fig. 4-18: Important requirements from Directives and Regulations
4
Standards and Regulations
37
The influences by requirements on lateral protection improve aerodynamics (ECE-R 73).
These are regarded as marginal for this study as well as influences on the front structure by
towing devices (77/389/EEC).
Finally a detailed recommendation for changes in length limitation with regard to active and
passive safety requirements is elaborated in this study. Chapter 9 will contain a detailed
explanation of how the new concept complies with all of the above identified regulatory
boundaries.
5
Build-up of CAD Models
5
Build-up of CAD Models
38
In this chapter the build-up of the CAD models that are required as input data for the
investigation is described. Therefore first a reference truck is defined. After this, three
optimised base concepts are derived, which can be used as the basis for a second
optimisation step.
5.1
Definition of Reference Truck
To evaluate the influence of optimisations on a 40 t-HGV truck, CAD data of a reference
model is built up. This reference model shall represent a state of the art long haul truck. As a
basis scan points of the outer skin of a 40 t-HGV tractor are used. Therefore a typical
representative tractor with a good aerodynamic performance according to the state of the art
design is chosen. A CAD model is derived from these scan points and their resulting curves.
The cabin is a common large standard cabin. To improve its aerodynamics, a roof spoiler
and two side spoilers are implemented in the CAD model. Missing components, like the
crash structure for example, are taken from a real tractor. Therefore a tractor, in use by fka,
is investigated and important dimensions are taken from it to complete the CAD model.
Especially, the limitations of dimensions and masses result in a similar appearance of the
tractors from different manufacturers. Fig. 5-1 shows that only design elements like the
geometry of lamps and the grille give a tractor the identity of a special brand. For that
reasons these design elements are limited to functional areas in the generic reference
model, so the tractor serves as a generic model.
Fig. 5-1:
Design elements of different manufacturers [WOL10]
In this study a conventional trailer with board walls is used for the reference truck as well as
for the optimised concept. The data for the semi-trailer are measured from a real semi-trailer.
Some of the trailer dimensions are shown in Fig. 5-2. To build up CAD data that are capable
5
Build-up of CAD Models
39
as a basis for an FE model, special attention is paid to the respective material thicknesses
and the joining technologies.
Fig. 5-2:
Dimensions of a standard semi-trailer [SCB10]
The resulting CAD model of the reference truck is shown in Fig. 5-3. This truck is used as a
basis for the evaluation of the new concept. It contains all important aerodynamic devices of
a modern truck.
Fig. 5-3:
Reference truck
5
5.2
Build-up of CAD Models
40
Optimised Base Concepts
As a first step three optimised base concepts are set up. After investigation of the base
concept properties one of these concepts is selected by means of a pre-assessment to
undergo further optimisation measures.
The models of the optimised base concepts are based on the reference CAD data. For that
reason the geometry of the integrated concept from the APROSYS project will be transferred
to the 40 t-HGV tractor of this study. Within this step, three different additional lengths
(400 mm, 800 mm, and 1200 mm) will be provided to the front structure of this reference
tractor. This also includes a repositioning of the front axle. The usage of CAD data simplifies
the consideration of structural changes in the FE models. The FE models for CFD, crash and
VRU protection simulations directly base on this CAD data.
The three base concepts are shown in Fig. 5-4. The length extension of 400 mm at the
optimised base concept 1 effects that there are slight disadvantages regarding the approach
angle, because the position of the front axle is not changed in this concept. But since this
concept is not designed for off road use, this disadvantage is accepted. The position of the
front axle and the stairs are reorganised in base concept 2 and base concept 3 to ensure a
sufficient approach angle and an easy entry for the driver. The length extension of base
concept 2 is 800 mm. The wheelbase is extended by 400 mm. Concept 3 has an extended
length by 1200 and a lengthened wheelbase by 800 mm. In the construction of these
optimised base concepts, important requirements from directives (see Fig. 4-18) are
considered. Beneath the requirements for passive safety (e.g. large radii for VRU protection)
also active safety requirements are considered. One important component is the windscreen.
To ensure the direct field of vision is comparable to the reference truck, a large curved
windscreen is needed. The side windows must be redesigned to minimise occultation by the
A-pillar. Because the trailer remains unchanged, it is not displayed in these pictures.
5
Build-up of CAD Models
Side view
41
Front view
Base concept 1
Reference plane
Larger edge radius
for improved
aerodynamics
400 mm length extension
Base concept 2
Reference plane
400 mm extension
of wheelbase
800 mm length extension
Base concept 3
Reference plane
800 mm extension of
wheelbase
1200 mm length extension
Fig. 5-4:
Optimised base concepts
Larger
windscreen
Isometric view
Smaller radius of
front and larger
radii at the edges
for improved
aerodynamics
Deflective shape
of front
6
Safety and Aerodynamic Concepts
6
Safety and Aerodynamic Concepts
42
In this chapter a detailed description of the completed FE simulations is realised. This
includes a description of the important technical knowledge and the results of FE simulations.
6.1
CFD Simulations
The most important aerodynamic fundamentals concerning 40 t-HGVs are described in this
chapter. Afterwards the optimisation of the new front structure is described.
6.1.1
Aerodynamic Fundamentals
Typical values for the aerodynamic drag coefficient of different vehicles are shown Fig. 6-1.
Whereas passenger cars have an aerodynamic drag coefficient (cD) between 0.25 and 0.42,
most trucks have a drag coefficient > 0.6. The reason for that are the large front area and the
dimensions of the truck that are optimised to carry as much payload as possible by
legislation. In addition, the drag coefficient of an articulated truck is larger than that of a semitrailer tuck, because of the larger gap between tractor and articulated trailer [HOE08].
0.9
0.8
cd value
0.7
0.6
0.5
0.4
0.3
0.2
Fig. 6-1:
cD value of different vehicle types [HOE08]
The aerodynamic drag increases in the area with high dynamic pressure in the front
(Fig. 6-2). The fitting stream in the roof area of the cabin results in a reduction of
aerodynamic drag. The cD value continuously increases in the rugged substructure of the
truck. A radical increase of aerodynamic drag results in the gap between cabin and trailer
that is caused by a low pressure area in this gap. This behaviour can be optimised by the
usage of spoilers on the roof and side flaps at cabin or a combined device of these two. In
the area of the trailer a fitting stream reduces the drag again. At the end of the trailer a
radical increase of the drag caused by a low pressure area exists.
Safety and Aerodynamic Concepts
43
Cummulative drag
6
X-position
Fig. 6-2:
Behaviour of aerodynamic drag at a truck [HOE08]
Important for the reduction of aerodynamic drag of a semi-trailer truck is the usage of a roof
spoiler on top of the cabin if the height of the trailer is larger than the height of the cabin. The
correct setting of the adjustable roof spoiler avoids having a second dynamic pressure area
at the trailer’s front wall (Fig. 6-3). However, it is important to adjust the spoiler in an optimum
position. If it is too steep, the aerodynamic drag also increases because of its own dynamic
pressure area. In addition a steep spoiler increases the negative pressure between the
driver's cab and the trailer. This results in a lateral flow and an enlargement of the separated
flow region in the following section of the trailer. A non optimised setting of the spoiler can
result in 3 % higher fuel consumption [HOE08].
Drag increase
Spoiler down
Spoiler up
Fig. 6-3:
Relevance of spoiler setting
The influence of an angular stream is shown in Fig. 6-4. The quotient of the tangential force
coefficient (cT), that results from the stream lateral to the driving direction and the aerodynamic drag coefficient (cD) directly depends on the stream angle. Especially streaming
angles between 3° and 15° have a large influence on the behaviour of trucks [HOE08].
6
Safety and Aerodynamic Concepts
44
1.6
1.4
Ct / Cw
cT/cD value
1.5
1.3
1.2
1.1
1.0
Inclined flow
5 10 15 20 25 30
Stream angle
Fig. 6-4:
Influence of stream angle [HOE08]
A reduction of the influence of angled stream is possible by the usage of an aerodynamic
package (Fig. 6-5). Especially of angle > 10° a high pressure area in front of the trailer’s front
wall increases the aerodynamic drag. With the usage of side spoilers, this area remains at
low pressure with a better aerodynamic drag [HOE08].
With aerodynamic
Without
aerodynamic
With aerodynamic
Without
aerodynamic
package
package
package
packagepackage
With aerodynamic
package
Without aerodynamic
Fig. 6-5:
Influence of the aerodynamic package at 10° stream angle [HOE08]
This shows that the usage of deflectors is very important. The difference in fuel consumption
of a truck using deflectors and a truck not using deflectors is shown in Fig. 6-6. A truck with
deflectors has lower fuel consumption. For that reason deflectors are already implemented in
the reference truck (see Fig. 5-3).
6
Safety and Aerodynamic Concepts
45
%
Difference in fuel consumption
125
120
115
without air deflectors
110
105
100
with air deflectors
95
90
70
70
80 80 90
90
100
100
Velocity [km/h]
Fig. 6-6:
Importance of deflectors [STÜ07]
Different measures to decrease the cD value by the usage of deflectors are shown in Fig. 6-7.
By the usage of deflectors a decrease of the of cD value > 21 % is possible, with the usage of
an optimised deflectors a decrease of up to 34 % is possible.
cD value
Fig. 6-7:
cD value
0.863 Basis
0.656 24.0 %
0.663 23.2 %
0.629 27.1 %
0.660 23.5 %
0.820
0.657 23.8 %
0.673 22.0 %
0.668 22.6 %
0.568 34.1 %
0.680 21.0 %
0.609 29.4 %
Decrease of cD value by air deflectors [HUC08]
4.2 %
6
Safety and Aerodynamic Concepts
6.1.2
46
CFD Simulations of the Reference Truck
The aim of the CFD simulations is to identify the aerodynamic performance of the different
concepts. Since the cD value is independent from the truck’s speed the flow velocity is arbitrary for the simulations. But to reproduce realistic conditions a velocity of the truck of
85 km/h (23.61 m/s) is accepted. This means the air flow towards the truck and the street
underneath the truck have a velocity of 85 km/h. The truck itself is a static wall. To consider
the influence of rotating wheels, these are admitted with a rotation speed equivalent to the
velocity of 23.61 m/s. The CFD model of the reference truck is shown in Fig. 6-8.
Velocity [m/s]
24
X-velocity
of air:
23.61 m/s
0
Rotation of wheels in X-direction:
-23.61 m/s
-24
23.61 m/s
X-velocity of street: 23.61 m/s
Fig. 6-8:
Velocity of important components of the CFD model (reference truck)
The target is to identify the aerodynamic performance of the new truck in comparison to the
reference truck. Therefore changes in the cD value, the flow and velocity of flow are analysed
as well as differences in pressure and the velocity. The relationship between velocity and
pressure is described by the equation of Bernoulli. It reveals that the energy resulting from
pressure and the energy resulting from velocity must be constant in sum. This is shown in
Fig. 6-9. In front of the truck the high pressure results in low velocity of the air. In the upper
part of the tractor there is an area of low pressure that results in a high velocity of air. Behind
the truck high turbulences occur as a third kind of energy. For that reason pressure and
velocity are low in that area.
Pressure
Velocity
Pressure [mbar]
40
Velocity [m/s]
30
Lowest pressure =
highest velocity
Turbulences
Stagnation point
-40
Fig. 6-9:
Pressure and velocity in the surrounding of the truck
0
6
Safety and Aerodynamic Concepts
47
The most important parameters for the determination of the aerodynamic drag are the
pressure and the friction resistance. The pressure resistance results from the pressure
distribution in the boundary layers of the truck. Fig. 6-10 shows the pressure in the boundary
layer of the truck. The highest pressure occurs in the stagnation point in the front area of the
tractor. In addition to that also at the mirrors high pressures can occur. This pressure
diversification results in a longitudinal force that is mandatory for the aerodynamic drag. The
friction resistance results from the velocity gradient between the truck (that is a stationary
wall) and the air flow around the truck with a high velocity. Because of the tangential
cohesion of the fluid (air), friction effects between the fluid and the surface of the truck result
in a second longitudinal force.
Pressure in the boundary layer
Velocity of streamlines
35
4
0
Velocity [m/s]
-4
Pressure [mbar]
Fig. 6-10: Pressure in the boundary layer and velocity of streamlines
Because rotating wheels are considered in the CFD model, the air adheres on the surface of
the wheels and starts to rotate in the wheel house (Fig. 6-11). This is an important effect on
the total aerodynamics of a vehicle. Additionally the drivetrain and the air inlets in the front of
the tractor are considered to model the flow through the tractor. These details are also
considered for the optimised concepts.
Rotating wheels
Air inlets and drivetrain
Velocity [m/s]
30
Velocity [m/s]
30
0
0
Front wheel
0.004
Crankshaft Gearbox
Fig. 6-11: Flow in the wheel house and the engine compartment
Engine
Cooler
Air inlet
6
Safety and Aerodynamic Concepts
48
A detailed analysis of the aerodynamics of the reference truck shows high turbulences with
high air speeds behind the main-mirror. In addition a high pressure occurs on the front
surface on these components. Another area with high pressure is the sun visor and the area
on the windscreen (underneath the sun visor). Also the windscreen wipers cause turbulences
and an area of high pressure.
High pressure under sun visor
Pressure [mbar]
4
-4
30
High pressure on
main-mirror surface
Turbulence behind main-mirror
0
Velocity [m/s]
Fig. 6-12: Optimisation potential at the main-mirrors and the sun visor
The main mirrors are required by law, so they must be considered also for the optimised
concept. But to evaluate the influence of the sun visor, this component is removed from the
reference truck. In an optimised concept the installation of windscreen wipers could be
improved by hiding them underneath outer skin parts. To erase the influence of the wiper
they are also removed from the reference truck.
The result of this new CFD simulation is compared with the conventional reference truck with
wipers and sun visor in Fig. 6-13. The reference truck with wipers and sun visor has a cD
value of 0.729. By omission of the sun visor and the wipers the cD value can be decreased to
0.703. This is a decrease of 3.57 % in comparison to the reference truck with wipers and sun
visor. The areas of high pressure that are reduced by omitting the sun visor and the mainmirrors are marked in Fig. 6-13. The basis for the comparison of the optimised concepts and
the reference tractor will be the best reference case, so the reference truck without sun visor
and wipers.
6
Safety and Aerodynamic Concepts
49
With wipers and sun visor
Without wipers and sun visor
4
Pressure [mbar]
4
Pressure [mbar]
-4
cD = 0.729
-4
cD = 0.703
Fig. 6-13: Influence of main-mirrors and sun visor
6.1.3
CFD Simulations of the Optimised Base Concepts
CFD Simulations are executed for all three optimised base concepts. Fig. 6-14 shows the
comparison of the pressure distribution of the reference truck and base concept 1.
Reference truck
Base concept 1
4
4
Pressure [mbar]
cD = 0.703
-4
Pressure [mbar]
-4
cD = 0.671
Fig. 6-14: Pressure distribution of reference truck and base concept 1
By extending the vehicle front by 400 mm the high pressure areas in the middle are reduced.
This leads to a reduced cD value of 0.671, which means a reduction of 4.61 % compared to
the reference truck. The pressure distributions of base concept 2 and base concept 3 are
shown in Fig. 6-15.
6
Safety and Aerodynamic Concepts
50
Base concept 2
Base concept 3
4
4
Pressure [mbar] -4
Pressure [mbar] -4
cD = 0.658
cD = 0.640
Fig. 6-15: Pressure distribution of base concept 2 and base concept 3
Base concept 2 and base concept 3 show further reduced areas of high pressure.
Furthermore the change-over from high pressure to low pressure areas are smoothened.
The cd value of base concept 2 is reduced by 6.39 % compared to the reference truck. Base
concept 3 achieves a reduction of 8.89 %. The velocities in the streamlines of all concepts
can be seen in Fig. 13-1 in the attachment of this study.
6.1.4
Selection of Concept for Additional Optimisation
For execution of further optimisation measures one concept is selected. Therefore the
general concept features are pre-assessed in regard to compliance with the permissible axle
loads and its operability is investigated. Fig. 6-16 shows measurements and forces working
on the tractor.
Reference
lTractor
GTractor
FFront
lWB
Fig. 6-16: Forces working on tractor
lTrailer
GTrailer
FRear
6
Safety and Aerodynamic Concepts
51
The loads for a tractor carrying a fully loaded trailer are assumed as follows:
GTotal  GTrailer  GTractor  18 t  g
Eq. 6-1
GTractor  8 t  g
Eq. 6-2
G Trailer  10 t  g
Eq. 6-3
FFront  6.5 t  g
Eq. 6-4
FRe ar  11.5 t  g
Eq. 6-5
The rear axle load FRear of 11.5 t must not be exceeded because of legal requirements. The
centre of gravity of the tractor is calculated in Eq. 5-6 and Eq. 5-7.
GTrailer  lTrailer  GTractor  lTractor  FFront  l Wb
Eq. 6-6
FFront  l Wb  GTrailer  l Trailer
GTractor
Eq. 6-7
l Tractor 
The reference truck has a wheelbase of 3730 mm. So the centre of gravity is 2318 mm in
front of the rear axle. Since base concept 1 has the same wheelbase as the reference truck
the centre of gravity can also remain unchanged to assure the compliance of maximum rear
axle load. To achieve this for base concept 2 with a wheelbase of 4130 mm the centre of
gravity must be at least 2643 mm in front of the rear axle. This means that the gravitational
centre has to be moved 325 mm towards the front. Because the concept provides more
design space in the front this can be achieved by accordant package measures. For base
concept 3 a shifting of the centre of gravity by 750 mm is required. Therefore more
comprehensive measures are necessary.
The extension of the wheelbase does not only complicate to assure the compliance of the
permissible rear axle load, it also has disadvantages regarding operability. Manoeuvring is
more difficult with vehicles with long wheelbases. The general concept features are preassessed in Fig. 6-17.
6
Safety and Aerodynamic Concepts
52
Base concept 1
Base concept 2
Base concept 3
Aerodynamic
performance
-
+
+
Compliance with
axle loads
+
o
-
Operability
+
o
-
-: moderate
o: neutral
+: good
Fig. 6-17: Pre-assessment of optimised concepts
The pre-assessment shows that base concept 2 is the best compromise. It has sufficient
improvement of the aerodynamic and safety concept and still ensures good operability.
Hence it is selected to undergo further aerodynamic optimisation.
6.1.5
Advanced Concept
The further optimisation measures aim for an additional reduction of high pressure areas in
the middle of the front structure and the low pressure areas at the front edges that cause
high flow velocities and high friction forces. Therefore a smaller curvature radius is applied to
the middle part of the front. In contrast, the edges are carried out with larger radii.
Furthermore the concept is equipped with optimised main mirrors that are adapted to the
front shape. Fig. 6-18 shows the further advanced concept.
Smaller radius to
reduce high
pressure areas
Bigger radii to
reduce high
velocity areas
r ≈ 320 mm
r ≈ 1600 mm
r ≈ 3120 mm
r ≈ 1130 mm
r ≈ 825 mm
Optimised
main mirrors
Fig. 6-18: Advanced concept
r ≈ 1600 mm
r ≈ 1600 mm
6
Safety and Aerodynamic Concepts
53
To prove that the requirements regarding manoeuvrability are fulfilled, a multi-body
simulation of the advanced concept is executed. Fig. 6-19 and Fig. 6-20 show the simulation
result. It can be seen that the requirements according to 97/27/EC are fulfilled.
Fig. 6-19: Manoeuvrability of advanced concept in top view
Fig. 6-20: Manoeuvrability of advanced concept (3D)
The advanced concept also fulfils the requirements regarding the external projections of the
cabin governed by 92/144/EEC. The advanced concept does not have any exterior parts that
face outwards so they could be dangerous for pedestrians. Furthermore the radii at the grill
are larger than 2.5 mm. The bumper covers are bended inwards as governed by the
regulation. Also the edges of the steps are rounded. Further paragraphs of 92/144/EEC are
related to parts that are not considered in this early concept stage like for example the door
handles, brand labels and wheel nuts. The general design changes of the advanced concept
do not have any effect on this level of detail. Hence it can be assumed that all requirements
can be met. Fig. 6-21 shows the arranged measures to achieve compliance with
92/144/EEC.
6
Safety and Aerodynamic Concepts
54
r = 5 mm
r = 20 mm
Fig. 6-21: Measures for compliance with 92/144/EEC
The lateral protection device remains unchanged compared to the reference truck. The
relocation of the entrance steps does not affect the protection device. Hence the concept can
fulfil the lateral protection device requirements set by 89/297/EEC and ECE-R 73 in the same
way as state of the art trucks with entrance steps behind the front axle (e.g. Renault
Magnum).
The configuration for the front impact pendulum test described in ECE-R 23 is shown in
Fig. 6-22. The advanced concept provides additional crush zone for energy absorption.
Hence it is to expect that the advanced concept shows better test results than the reference
tractor. There are no disadvantages to expect regarding the roof strength and rear wall
strength test, because there are no changes in general structural cabin design.
Δs
Fig. 6-22: Pendulum test
CFD Simulations of the advanced concept reveal that the cD value is reduced by 6.11 %
compared to base concept 2. Compared to the reference truck a reduction of 12.10 % is
achieved. Fig. 6-23 and Fig. 6-24 show the pressure distribution of base concept 2, the
6
Safety and Aerodynamic Concepts
55
advanced concept and the reference truck. The Figures also disclose that the high pressure
area on the optimised main mirrors is reduced compared to the reference mirrors.
Base concept 2
Advanced concept
4
4
Pressure [mbar] -4
Pressure [mbar]
cD = 0.658
-4
cD = 0.618
Fig. 6-23: Advanced concept compared to base concept 2
Reference
Advanced concept
4
4
Pressure [mbar]
-4
cD = 0.703
Fig. 6-24: Further optimised concept compared to reference
Pressure [mbar]
cD = 0.618
-4
6
Safety and Aerodynamic Concepts
6.2
56
Wind Tunnel Tests
To validate the CFD simulation results wind tunnel test are executed at the Chair of Flight
Dynamics at the RWTH Aachen University. The setup of the test facilities can be seen in
Fig. 6-25. The operating speed range of this wind tunnel reaches from 0 to 70 m/s.
14.6 m
Turbine
Drive
Exhaust
8m
3m
Nozzle
Diffusor
USK (Wind Tunnel)
Measuring Station
Fig. 6-25: Wind tunnel at Chair of Flight Dynamics (RWTH Aachen University)
For the wind tunnel tests physical models of the reference tractor, the optimised tractor and
the trailer are manufactured in a 1:10 scale. The model is mostly made from birch multiplex
wood and Ureol-plastics. Parts that are needed in multiple executions, like the tyres for
example are casted from polyurethane casting resin. Fig. 6-26 shows the hardware models
mounted to the test bench in the wind tunnel.
To measure the pressure forces and friction forces both models are mounted to the test
bench successively. Then different air flow velocities between 20 m/s and 55 m/s are
applied. A balance is used to measure the occurring forces. To reproduce realistic conditions
the whole model, which means tractor and trailer, has to be fitted to the balance. At this point
a simplification needs to be accepted, because the 1:10 model is too big for the balance.
Therefore only the tractor is connected to the balance. It does not have any contact with the
6
Safety and Aerodynamic Concepts
57
test bench frame, so the forces in all directions can be detected by the balance. The trailer,
however, is fixed to the test bench frame. This simplification is visualised in Fig. 6-27. This
way the friction resistance of the trailer and the low pressure area behind the trailer is
neglected, but the flow pattern of the model reproduces realistic conditions. Nevertheless,
this test configuration allows measuring the difference between the two tractor concepts.
Fig. 6-26: Hardware models for wind tunnel tests
Fixed coupling between test bench
frame an trailer
No contact between tractor and
test bench frame
Fig. 6-27: Mounting of model with simplification
Balance
6
Safety and Aerodynamic Concepts
58
The measured results of the wind tunnel test are shown in Fig. 6-28. The cD value is plotted
against the air flow velocity. The averaged cD value over the flow velocity is 0.625 for the
reference truck and 0.427 for the advanced concept. This means a reduction 31.68 %.
0.8
0.7
c D value
0.6
0.5
0.4
0.3
0.2
0.1
0
15
20
Reference
25
30
35
40
45
50
55
60
Velocity
Optimised
Fig. 6-28: Measured cD values with simplified test setup (trailer fixed to test bench frame)
These results show a deviation from the simulation results. The simulations bring out a cD
value of 0.703 for the reference truck and a value of 0.618 for the advanced concept, which
means a reduction of 12.11 %. The deviation between the simulation results and the test
result is caused by the simplification of the measuring. Because of the disregard of the
friction forces at the trailer and the low pressure area behind the trailer the measured cD
values are lower than the calculated ones.
Furthermore also the difference between the reference truck and the advanced concept is
bigger in the test results than in the simulation results. Because of the simplification of the
measuring only effects caused by the different front shapes of the tractor are detected. The
negative influence of the usage of the same trailer for the reference truck and the advanced
concept is not measured. The fact that the difference between reference truck and advanced
concept is bigger when trailer effect are neglected reveals that in a reverse conclusion there
is even more potential for improvement of the concept’s aerodynamic properties by adapting the trailer accordingly.
To investigate the adequacy of the simulation results additional simulations are executed. In
doing so the simplification of the tests are also considered in the simulation. This way a cD
value of the reference truck of 0.625 was calculated. This value shows complete consistency
with the test result. The simulation result for the advanced concept reveals a cD value of
0.439. This means a deviation of 2.81 %. Due to this good compliance of the test results with
the calculated values is proven.
6
Safety and Aerodynamic Concepts
59
Besides measuring of the cD values, analysis of the flow pattern is also executed by means
of smoke plumes. An example of these investigations is shown Fig. 6-29. These tests are
also documented as video files. Generally it can be seen that the streamlines show a
smoother course at the advanced concept.
Reference
Advanced Concept
Fig. 6-29: Analysis of flow pattern with smoke plumes
6.3
Crash Simulations
Besides the aerodynamics also safety issues shall be improved by the advanced concept.
For the evaluation of the passive safety performance crash simulations are executed. It
cannot be assumed that the change front geometry without improving the crash structures
has positive effects. For that reason a crash management system is designed in the first
step. Therefore functional requirements are defined. After this, a CAD model is built up
based on a topology optimisation.
To define the simulation setups, HGV accident statistics are investigated. This is followed by
the execution of the simulations and the according evaluation.
6.3.1
Crash Management System
The advanced concept provides additional design space in the front area due to the length
extension of the front. This space can be used to achieve an optimisation of the safety
concept by adding an additional crash management system.
6.3.1.1
Definition of Functional Requirements
The crash management system should optimise the energy absorption behaviour and also
serve as an underrun protection system for passenger cars. Underrun protection systems
have to fulfil the requirements given in ECE-R 93. These are illustrated in subchapter 4.1.3.3.
For the development of the crash management system the required dimensions are
considered and the bearable force levels are checked in FE simulations.
6
Safety and Aerodynamic Concepts
60
The crashworthiness target values need to refer to the passenger car, because the accident
severity will be much heavier for car occupants than for the truck occupants in case of a car
to truck crash. But such values for a development of a truck crash management system
cannot be found in the executed literature research. For that reason limit values for common
car crash tests are investigated, because they are defined according to the physical limits of
human body. Fig. 6-30 shows the EURO NCAP crash test setup. For the crash evaluation, a
dummy is used. The evaluation points on this dummy are displayed in Fig. 6-31.
40 % overlap = 40 % of the width of the widest
part of the car (not including wing mirrors)
1000 mm
540 mm
64 km/h
Fig. 6-30: Setup of EURO NCAP crash test [CAR11]
Head: acceleration and HIC
Neck: forces
Thorax: depression
Upper leg: forces
Knee: displacement
Lower leg: forces
Foot: displacement (brake pedal)
Fig. 6-31: Evaluation points on a dummy [CAR11]
The recorded values at the dummy also depend on restraining system like seat belts and
airbags. These influences should not be considered for the design of a truck crash
management system. Hence car related limit values are required.
Such car related values are used in the ULSAB Project. They are listed in Fig. 6-32. Only
intrusion and displacements are considered in these values. But for a complete evaluation of
6
Safety and Aerodynamic Concepts
61
the accident severity the occurring accelerations need to be considered. Both of the values,
intrusion and acceleration, should be as low as possible. A low acceleration can be achieved
by a bigger deformation path, but this automatically leads to an increase of the intrusions.
Since the human body only tolerates limited accelerations but huge intrusions also cause
heavy injuries a good compromise between these values is acquired.
Crash Event
US NCAP Front Impact
Crashworthiness Targets
Overall dynamic deformation ≤ 650 mm
Steering column displacement ≤ 80 mm in X-direction
Crash Event
EURO NCAP
Crashworthiness Targets
A-pillar displacement < 650 mm
Footwell intrusion < 80 mm
Steering column displacement ≤ 80 mm in X- direction
Fig. 6-32: Crashworthiness targets of ULSAB [ULS98]
Target values for intrusion are also used in the SLC project. Furthermore also maximal
acceleration is considered. For this reason accelerations are recorded at the lower end of
both B-pillars and at the middle tunnel. The decisive value is the average of these values.
Fig. 6-33 shows the SLC target values. Adverse in the present case is that the simulation
model and the evaluation of the simulation respectively have a high degree of complexity.
Due to this again the only intrusions into the car’s firewall and the accelerations at the rear seat are used for the evaluation of the simulation results. Similar to the previously discussed
projects also a EURO NCAP crash is the basis for the comparison. For this purpose also a
EURO NCAP crash is simulated as shown in Fig. 6-34. The according intrusions and
accelerations can be seen in Fig. 6-35 and Fig. 6-36 respectively.
6
Safety and Aerodynamic Concepts
62
Reference
SLC
Peak Intrusion Depth (mm)
POINT
TARGET
SLC
Footwell 
< 100
53
Footwell 
< 100
51
Footwell 
< 100
42
Wheelhouse 
< 100
43
Footrest 
< 100
35
Shaft hole 
< 100
49
A-plr ave
< 20
19
Shocktower
< 100
84
Steering
< 100
16
Door gap
---
20
Pulse amax
 55 g
56 g
Seat torsion
<
80
40
4
6
5
Fig. 6-33: Target values defined in SLC development [BER09]
Fig. 6-34: EURO NCAP Crash
1
2
3
6
Safety and Aerodynamic Concepts
63
Intrusion
[mm]
200
150
100
50
0
Max = 370 mm
Fig. 6-35: Intrusions into the car’s firewall after the EURO NCAP crash
Rear seat left side
200
Rear seat right side
175
Acceleration [g]
150
125
100
75
50
25
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 6-36: Acceleration at the car’s rear seats during the EURO NCAP crash
6.3.1.2
Concept Design
Considering the modes of deformation that energy-absorbing elements undergo, aluminium
systems make it possible to absorb significantly more energy per unit of weight than
traditional steel systems. As a thumb rule, the light-weighting potential exceeds 40 %
[GIL04]. The higher energy absorption capacity of aluminium compared to steel is illustrated
in Fig. 6-37, which shows a qualitative comparison of two different crash profiles. One of
them is made from St14 steel sheet. The other one is made from an aluminium extrusion
profile (AlMgSi0.5). Because of the higher force level the aluminium profile absorbs more
energy than the steel profile.
Safety and Aerodynamic Concepts
64
Force
6
AlMgSi0.5
St14 Sheet
Path
Fig. 6-37: Energy absorption of crash elements [OST92]
For that reason the usage of aluminium for crash structures in passenger cars is widely
spread. The application of extruded crash bumpers with crash boxes is a common way to
realise such systems. Fig. 6-38 shows an example. These systems are characterised by their
high effectiveness and low complexity.
Fig. 6-38: Extruded bumper beam with crash boxes [GIL04]
To further increase the effectiveness of crash management systems honeycomb structures
as shown in Fig. 6-39 can be used. The energy absorption potential of these structures is
higher than of simple extrusion profiles. The disadvantages regarding the manufacturing and
joining complexity however avoid a higher market penetration of this technology presently.
Fig. 6-39: Honeycomb structures for crash modules
6
Safety and Aerodynamic Concepts
65
Furthermore, an unconventional approach is considered. To improve the crash performance
of trams transversally mounted structures are developed currently. As an example the
“safetram” system is shown in Fig. 6-40. An advantage of this system is that it can face
multiple accident scenarios. For example, it is designed to dampen a head-on shock at
20 km/h with an identical tramway weighing 35 t or a 45°-collision at 25 km/h with a light
commercial vehicle (3 t) [GIL04].
Fig. 6-40: “Safetram” system for trains [GIL04]
The properties of the three discussed concepts are abstracted in Fig. 6-41. The concept with
extruded bumper beams and crash boxes shows good performance and is a well known
technology. Hence it is selected for the first approach.
Extruded beams
with crash boxes
Safetram crash
module
Honeycomb
structures
Effectiveness
+
o
+
Manufacturing
complexity
+
+
o
Complexity of joining
+
+
-
-: moderate
o: neutral
+: good
Fig. 6-41: Assessment of possible crash management systems
To assign the optimal structural shape for the crash management system a topology
optimisation of the free space is executed. Pictures of the topology optimisation are shown in
Fig. 6-42.
6
Safety and Aerodynamic Concepts
66
Model of free
design space
Applied
load
Optimised topology
for crash structure
Fig. 6-42: Topology optimisation of free design space
The results of the topology optimisation are interpreted as illustrated in Fig. 6-43. The upper
crash bumper improves the self protection performance. The lower bumper serves as an
underrun protection device. The additional two vertical beams are added to consider different
bumper heights of possible accident opponents. This way the partner protection performance
is enhanced.
To avoid redundancy of bumper systems the original steel bumper is omitted. Furthermore
the lateral parts of the steel bumper are integrated into the crash management system as
illustrated in Fig. 6-43.
Self
protection
Front underrun
protection
Reinforcement for
ECE-approval
Aluminium
crash boxes
Fig. 6-43: Additional aluminium crash management system
6.3.1.3
ECE-R 93 Test
To check the requirements given in ECE-R 93 the simulation model shown in Fig. 6-44 is
build up. The defined forces are applied on the prescribed test points. The force curves in
Fig. 6-45 show that the underrun protection device is able to withstand the defined forces
without plastic deformation.
6
Safety and Aerodynamic Concepts
67
Fig. 6-44: Test configuration (ECE-R 93)
Left side
100
Right side
Force [kN]
80
Left side
200
Right side
150
60
100
40
50
20
0
0
0
100 200 300 400 500 600 700
0
Time [ms]
100 200 300 400 500 600 700
Fig. 6-45: Force levels
6.3.2
Definition of Representative Crash Simulation Setups
To define simulation setups HGV accident statistics are investigated to find out the most
significant accident scenarios.
6.3.2.1
HGV Accident Statistics
The crash structure of the tractor shall serve for self-protection and for partner protection.
The following section will analyse available statistics to determine typical accident scenarios
involving the frontal structure of a truck and derive affected relevant target population of road
6
Safety and Aerodynamic Concepts
68
user categories. The statistical findings serve to select the crash simulation setups that best
characterise the passive safety performance.
To identify the target population, the number of fatalities in different accident scenarios is
estimated. The total number of fatalities with involvement of HGVs in 2008 is estimated at
7070 in a study executed by TRL based on road casualty numbers for the EU-27 countries
[TRL10].
The distribution of fatalities in accidents with involvement of HGVs on the different types of
road users is shown in Fig. 6-46. These values apply for the EU18 countries. They are
considered to be representative, so they can be scaled to execute coarse estimations for
Europe. In association with the total amount of 7070 fatalities per year, the numbers of car
occupants, truck drivers and VRUs killed in accidents with HGV involvement can be
estimated. This method yields 1555 killed VRUs, 3535 car occupants and 989 truck drivers
per year.
Others
989
(14 %)
VRU
1555
(22 %)
Passenger car
3535
(50 %)
Trucks
989
(14 %)
Fig. 6-46: Distribution of fatalities with HGV involvement [ERS08]
The relevant target population consists of those fatally injured road users that are hit by the
front of the truck. Fig. 6-47 shows distributions of killed and severely injured (KIS) VRUs in
prominent accident scenarios determined by four different authorities. Assuming that these
values are representative and the percentages of killed and severely injured people are
analogue to shares of fatalities, the number of VRUs killed in the different scenarios can be
determined.
HGV front vs.
VRU when
taking off
10
IVECO [%]
Typical situation
DEKRA [%]
Scenario 1
Description
69
Cidaut [%]
Safety and Aerodynamic Concepts
Volvo [%]
6
26
7
4
20
9
27
26
18
Scenario 2
HGV vs. VRU
when
reversing
20
Scenario 3
HGV vs. VRU
crossing road
20
Scenario 4
HGV side vs.
VRU when
turning
20
Scenario 5
HGV rear vs.
unprotected,
driving
straight
10
13
22
13
Others
38
Others
-
25
13
15
-
24
Fig. 6-47: Killed and severely injured VRUs in prominent HGV-VRU scenarios [HDV05]
6
Safety and Aerodynamic Concepts
70
In scenario 1 and scenario 3 the VRUs involved in one of these scenarios can benefit from
the developed front design. For all other scenarios a mitigation of the accident consequences
cannot be expected.
In a pessimistic estimation the total number of involved VRUs in scenario 1 and scenario 3
can be calculated according to Eq. 6-8. An optimistic estimation is determined in Eq. 6-9. The
percentages for each scenario determined by one authority are summed up. The minimum
sum is used for the optimistic estimation; the maximum sum is used for the pessimistic
estimation. In this context the pessimistic estimation leads to a higher number of fatalities,
but in a reverse conclusion also a higher benefit is generated by the advanced concept that
way. This approach shows that a number from 467 to 544 VRUs can benefit from the
developed front design.
1555  (10  20)%  467
Eq. 6-8
1555  (26  9)%  544
Eq. 6-9
An analogue investigation is also executed for car occupants. Fig. 6-48 shows the
distribution of killed and severely injured car occupants in prominent accident scenarios. The
car is hit by the front of the truck in the scenarios 1, 2, 3 and 5. For these cases positive
effects for the car occupants are expectable caused by the optimised truck front design. The
pessimistic estimation is determined in Eq. 6-10. The value for the optimistic estimation is
calculated in Eq. 6-11.
3535  (19  19  16  6)%  2121
Eq. 6-10
3535  (30  5  15  15)%  2298
Eq. 6-11
The percentages for the killed and severely injured HGV occupants in prominent collisions
scenarios are illustrated in Fig. 6-49. An optimised frontal structure can yield positive effects
for scenario 3, Scenario 4 scenario 5 and - with some limitations - scenario 1. In these
scenarios the truck front gets or could get in contact with an obstacle.Analogue to the
previous calculations a number from 613 to 989 killed HGV occupants is determined in
Eq. 6-12 and Eq. 6-13.
989  (52  2  6  2)%  613
Eq. 6-12
989  (21  79)%  989
Eq. 6-13
DEKRA
[%]
IVECO
[%]
21
5
27
19
11
15
16
11
Scenario 1
19
Scenario 2
19
Oncoming
traffic HGV
front vs. car
side
Scenario 3
30
Oncoming
traffic HGV
front vs. car
front
Traffic ahead
in same
direction HGV
front vs. car
rear
Scenario 4
Typical situation
Traffic ahead
in same
direction car
front vs. HGV
rear
12
6
10
Scenario 5
Description
71
Cidaut
[%]
Safety and Aerodynamic Concepts
Volvo
[%]
6
Intersection
HGV front vs.
car side
15
6
18
13
9
7
6
9
32
15
11
15
Scenario 6
Intersection
car front vs.
HGV side
12
Scenario 7
Lane change
accident HGV
side vs. car
side
10
Others
1
Others
-
Fig. 6-48: KSI passenger car occupants in prominent HGV-car collisions [HDV05]
Volvo
[%]
Cidaut
[%]
DEKRA
[%]
IVECO
[%]
Scenario 1
HGV single
driving off
road
35
52
21
30
Scenario 2
HGV single
rollover on
road
12
8
0
11
Scenario 3
HGV - HGV
collision,
oncoming
traffic
front vs. front
10
2
0
13
Scenario 4
72
HGV - HGV
collision,
traffic ahead
in same
direction
front vs. rear
20
6
79
25
Scenario 5
Safety and Aerodynamic Concepts
HGV passenger car
collision,
oncoming
traffic, HGV
front vs. car
10
2
0
2
Others
6
Others
Description
Typical situation
-
24
Fig. 6-49: Killed and severely injured HGV occupants in prominent collisions [HDV05]
These statistical findings suggest defining a set of crash simulation runs.
19
6
Safety and Aerodynamic Concepts
6.3.2.2
73
Passenger Car Occupant Protection
For the definition of simulation setups for the analysis of the car occupant protection
performance only those scenarios from the statistical findings are considered, in which the
truck front has contact to the accident opponent. These are the scenarios 1, 2, 3 and 5. The
biggest percentages can be covered with simulation configurations representing a frontal
crash and a rear shunt. In frontal accidents an offset between the car and the truck often
occurs, because the two accidents opponents are approaching on different sides of the road.
Hence two simulation setups are considered for the front crash: One without offset and one
with an offset of 30 %. As an example the simulation setup for the offset crash can be seen
in Fig. 6-51 and Fig. 6-52. To represent scenario 3 rear shunt simulations with two different
impact velocities are executed. In these setups the car is standing and the truck has an
impact speed of 20 km/h and 40 km/h respectively.
The frontal collision setup with 30 % offset is also used by DEKRA to evaluate the partner
protection performance of trucks as shown in Fig. 6-50. In this car crash test configuration
the truck has a velocity of 21 km/h. The passenger car’s speed is 42 km/h [DEK10]. These
velocity values represent a typical intra-urban accident scenario. Hence the same values are
used for the simulation setup.
Crash configuration
Truck after crash
Fig. 6-50: DEKRA truck against car crash test [DEK10]
Fig. 6-51: Simulation configuration in top view
Car after crash
6
Safety and Aerodynamic Concepts
74
Fig. 6-52: Simulation configuration in isometric view
Crash test with similar configuration are also executed by truck manufacturers. Volvo for
example completes a crash test illustrated in Fig. 6-53 to develop the Front Underride
Protection System (FUPS). The truck has a velocity of 65 km/h and hits the car with 50 %
offset. The target of this crash test is to identify the crash performance of the tractor using a
FUPS. Therefore the energy absorption behaviour is evaluated [VOL10c].
Crash configuration
Crash test
Truck after crash
Fig. 6-53: Volvo truck against car crash test [SCH06]
In addition this crash tests is completed with different velocities of the car (56 km/h, 64 km/h
and 75 km/h) and with different kinds of cars (super mini and small family). So it is possible
to design the FUPS for different crash severities [VOL10c]. Further information about the
FUPS can be found in [UTA05].
Impact force
Volvo FUPS
maximum force
Large car
Medium car
Small car
Volvo FUPS trigging force
Time
Fig. 6-54: Results of Volvo crash test [VOL10c]
6
Safety and Aerodynamic Concepts
6.3.2.3
75
VRU Protection
For the evaluation the VRU protection characteristics of the advanced concept in comparison
to the reference truck, several simulations are completed. The design changes of the
advanced concept are limited to the front of the truck. Hence the VRU is hit by the front of the
truck in the simulation setup. To represent a big percentage of all fatal VRU accidents found
in the accident statistics, two different impact zones are considered for both of the concepts
as shown in Fig. 6-55.
Centre
Edge
Fig. 6-55: Consideration of two different impact zones
For each impact zone several human body models are investigated. These are:


6 year old child
5 % female



50 % male
95 % male
Cyclist
The percentages in the declaration of the model indicate how many percent of the female or
male population fall below the size of the respective model according to statistics.
The effect on VRU protection performance is identified by analysing the crash kinematics. An
example of the dummy kinematics of a 50 % male hitting a light duty truck in straight forward
driving with 40 km/h is shown in Fig. 6-56. The evaluation of the VRU protection behaviour of
the new concept is based on this scenario [HAM09]. An example of the vehicle front model
(multi-body model) in a pedestrian accident scenario is shown in Fig. 6-56.
6
Safety and Aerodynamic Concepts
76
t = 0,02 s
t = 0,16 s
t = 0,32 s
t = 0,48 s
t = 0,64 s
t = 0,80 s
0.02 s
0.48 s
0.16 s
0.64 s
0.32 s
0.80 s
Fig. 6-56: Kinematics of the 50 % male in the straight forward driving situation [FAS08]
6.3.2.4
Self Protection
For the evaluation of the self protection performance scenario 1 and scenario 4 in Fig. 6-49
represent the biggest percentages of fatal accidents. Since the critical obstacle in scenario 1
cannot be identified, scenario 4 is used for the build up of a simulation setup.
This configuration is also used by truck manufacturers. A crash test executed by MAN is
shown in Fig. 6-57. The truck hits a barrier with a velocity of 30 km/h and an offset of 50 %
between truck and barrier. The deformable barrier has a weight of 20 t. The target is to
identify the intrusion and the energy absorption behaviour of the tractor’s structure. Additionally the evacuation behaviour to rescue the driver is evaluated. Especially the cabin
is tested with this crash configuration.
Crash configuration by MAN
Deformed structure in FE simulation
door structure
cabin support
Fig. 6-57: Crash configuration by MAN [BAC09]
longitudinal
beam
6
Safety and Aerodynamic Concepts
77
Volvo is completing similar crash tests against an 850 t heavy steel block barrier with an
angle of 30°. This configuration can be seen in Fig. 6-58. The truck has a velocity of 30 km/h.
This test corresponds to a 50 km/h crash into the rear of a trailer. Again the target is to
identify of the energy absorption, cabin strength, cabin attachment and the evacuation
behaviour of the cabin structure. In addition occupant injuries are evaluated [VTN09].
Side view
Top view
Fig. 6-58: Crash configuration by Volvo [VTN09]
For the FE simulations of the self-protection tests in this study, the tractor hits a semi-trailer
with a velocity of 30 km/h and an offset of 50 % between truck and the trailer. The crash
performance is evaluated by analysis of the intrusions and the energy absorption behaviour.
The FE model configuration used for the simulations can be seen in Fig. 6-60 and Fig. 6-59.
Fig. 6-59: Simulation configuration in top view
Fig. 6-60: Simulation configuration in isometric view
6
Safety and Aerodynamic Concepts
6.3.3
78
Results of Crash Simulations
The results of the crash simulations are presented in the following.
6.3.3.1
Comparison of Partner Protection Performance
As an example the simulation results for the frontal collision with 30 % offset are
investigated. The recorded data for all other car to truck simulations can be seen in
subchapter 13.2 of the appendix.
The comparison of the simulation results of the reference truck and the advanced concept
are shown in Fig. 6-61.
Reference truck
Advanced concept
Fig. 6-61: Simulation results with additional crash management system
6
Safety and Aerodynamic Concepts
79
The evaluation of the intrusions and the occurring accelerations show differences in the
crash behaviour. These data are illustrated in Fig. 6-62, Fig. 6-63 and Fig. 6-64.
Reference truck
Advanced concept
Intrusion
[mm]
180
140
100
60
20
0
Max = 186.1 mm
Max = 174.4 mm
Fig. 6-62: Intrusions into the car’s firewall after the crash
The maximum intrusion into the car’s firewall after the crash with the reference truck is
186.1 mm. After the crash with the advanced concept the peak value is 174.4 mm.
Furthermore the advanced concept shows reduced values in the steering wheel area. This
area is critical, because intrusions here can easily cause contact between the car occupant
parts of the car which increase the risk of injuries.
100
Rear seat left side
Rear seat right side
Acceleration [g]
80
60
40
20
0
0
20
40
60
80
Time [ms]
100
120
140
Fig. 6-63: Acceleration at the car’s rear seats during crash with reference truck
160
6
Safety and Aerodynamic Concepts
80
100
Rear seat left side
Rear seat right side
Acceleration [g]
80
60
40
20
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 6-64: Acceleration at the car’s rear seats during crash with the advanced concept
Analysing the accelerations it becomes conspicuous that the application of the crash
management system leads to a reduced peak value below 70 g (compared to 85 g for the
reference truck). In conclusion, the partner protection performance is enhanced.
To evaluate the trucks behaviour during the crash the forces inside the side members are
investigated. Fig. 6-65 shows the evaluation points for the recording of the occurring forces.
The results are shown in Fig. 6-66 and Fig. 6-67.
1: Left side
member front
2: Left side
member rear
3: Right side
member front
4: Right side
member rear
Fig. 6-65: Evaluation points for occurring forces
6
Safety and Aerodynamic Concepts
81
400
1
3
350
2
4
Force [kN]
300
250
200
150
100
50
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 6-66: Forces in the side members of the reference tractor during the crash
400
1
3
350
2
4
Force [kN]
300
250
200
150
100
50
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 6-67: Forces in the side members of the advanced concept during the crash
The evaluation of the forces in the side members of the truck shows that the forces are
reduced. This way the self protection performance is improved.
To further clarify the positive effects of the crash management system the different amounts
of absorbed energy are shown in Fig. 6-68 and Fig. 6-69. It can be seen that the share of
6
Safety and Aerodynamic Concepts
82
energy absorbed by the car is reduced in case of the advanced concept with crash
management system compared to the reference truck.
The investigations show that the application of the crash management system can reduce
the accident severity. Hence all further simulations are executed for the advanced concept
with crash management system.
225
Total amount
of absorbed
energy
200
Energy [kJ]
175
Energy
absorbed
by car
150
125
Energy
absorbed
by truck
100
75
50
25
0
0
20
40
60
80
100
Time [ms]
120
140
160
Fig. 6-68: Energy absorption behaviour of reference truck
225
Total amount
of absorbed
energy
200
Energy [kJ]
175
Energy
absorbed
by car
150
125
Energy
absorbed
by truck
100
75
50
25
0
0
20
40
60
80
100
Time [ms]
120
140
160
Fig. 6-69: Energy absorption behaviour of advanced concept
In Fig. 6-70, Fig. 6-71 and Fig. 6-72 the maximum values of all partner protection simulations
are contrasted. All according figures can be seen in subchapter 13.2 of the appendix. It can
be seen that except for one value all values have improved, so a mitigation of the accident
6
Safety and Aerodynamic Concepts
83
severity can be assumed for these cases. A more detailed investigation of the intrusion in the
frontal crash without offset is illustrated in Fig. 6-72. It reveals that the maximum value of
intrusion only occurs in a small area on the upper right side. The intrusions in the critical
steering wheel area and the rest of the firewall however are reduced.
Frontal crash with offset
Reference truck
Advanced concept
max. intrusions into the car’s firewall [mm]
186.1
174.4
max. acceleration
[g]
85
70
max. force in side member
[kN]
305
240
Fig. 6-70: Comparison of maximum values for frontal crash with offset
Frontal crash without offset
Reference truck
Advanced concept
max. intrusions into the car’s firewall [mm]
175.9
187.3
max. acceleration
[g]
250
112.5
max. force in side member
[kN]
427
235
Fig. 6-71: Comparison of maximum values for frontal crash without offset
Reference truck
Advanced concept
Intrusion
[mm]
180
140
100
60
20
0
Max = 175.9 mm
Max = 187.3 mm
Fig. 6-72: Intrusions into the car’s firewall after frontal crash without offset
6
Safety and Aerodynamic Concepts
84
Rear shunt
Reference truck
Advanced concept
max. intrusions into the car’s rear floor panel [mm]
-80.2
-34.8
max. acceleration
[g]
170
59
max. force in side member
[kN]
90
74
Fig. 6-73: Comparison of maximum values for rear shunt
6.3.3.2
Comparison of VRU Protection Performance
As an example the result of one VRU protection simulation for the reference tractor is shown
in the picture sequence in Fig. 6-74. In comparison to this the results for the advanced
concept using the same configuration is illustrated in Fig. 6-75.
It can be seen that the reference tractor overruns the human model. In contrast, the
advanced concept deflects the pedestrian away from the truck after the initial contact. This
way the overrun is prevented. Picture sequences of all further VRU protection simulations
can be seen in subchapter 13.2.
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 6-74: Reference tractor against 50 % male
6
Safety and Aerodynamic Concepts
85
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 6-75: Optimised concept against 50 % male
The results of all simulations are summarised in Fig. 6-76. The overrun is prevented in 100 %
of the simulated cases for the advanced concept. In contrast simulations with the reference
tractor lead to an overrun in 70 % of all cases.
Position
Centre
Edge
Cyclist
Human model
Reference
Advanced concept
6 year old child
overrun
no overrun
5 % female
overrun
no overrun
50 % male
overrun
no overrun
95 % male
overrun
no overrun
6 year old child
no overrun
no overrun
5 % female
no overrun
no overrun
50 % male
no overrun
no overrun
95 % male
overrun
no overrun
50 % male
overrun
no overrun
Fig. 6-76: Evaluation of VRU protection simulations
To quantify the possible reduction of fatalities due to the implemented measured
comprehensive evaluation of traffic accident statistics in further studies are required.
6.3.3.3
Comparison of Self Protection Performance
The result of the simulation is shown in Fig. 6-77. The comparison of the simulation results
already shows that the self protection performance of the advanced concept is improved.
6
Safety and Aerodynamic Concepts
86
The advanced concept absorbs more crash energy in the front part of the cabin. This
becomes more evident when the intrusions into the front of the truck and the front lateral
beam are evaluated. These are shown in Fig. 6-78 and Fig. 6-79.
The evaluation of the intrusions into the tractor front reveals that both the maximum value
and the average values are lower at the advanced concept’s front. From this follows that the survival space for the driver is larger and also the evacuation behaviour to rescue the driver
is improved. The curves of occurring forces in the side members during the crash are shown
in Fig. 6-80 and Fig. 6-81.
Reference truck
Advanced concept
Fig. 6-77: Simulation results with additional crash management system
6
Safety and Aerodynamic Concepts
87
Reference truck
Advanced concept
Intrusion
[mm]
400
300
200
100
0
Max = 373.1 mm
Max = 351.5 mm
Fig. 6-78: Intrusion into front
Advanced concept
Reference truck
Intrusion
[mm]
200
150
100
50
0
Max = 148.8 mm
Max = 59.1 mm
Fig. 6-79: Intrusion into the front lateral beam
300
Force [kN]
250
1
3
2
4
200
150
100
50
0
0
20
40
60
80
100
120
Time [ms]
140
160
180
200
Fig. 6-80: Forces in the side members of the reference tractor during the crash
220
6
Safety and Aerodynamic Concepts
88
300
Force [kN]
250
1
3
2
4
200
150
100
50
0
0
20
40
60
80
100
120
Time [ms]
140
160
180
200
220
Fig. 6-81: Forces in the side members during the crash with crash management system
All curves show lower peak values, which leads to a reduction of the accident severity and
also the evaluation of the occurring forces shows an improvement of the self protection
performance.
The analysis of the simulation furthermore reveals that optimisation potential also exists in
trailer design. It can be seen in Fig. 6-82 that the upper part of the crash management
system hits the rear bumper of the trailer. The mounting of the rear bumper however
collapses, so the crash management is not able to absorb lots of energy. Instead the side
member of the trailer hits the cabin and causes high intrusions. This behaviour can be
approved by alternative trailer concepts to mitigate accident consequences in this scenario.
Fig. 6-82: Side view of crash kinematics
7
Technical Assessment
7
Technical Assessment
89
To evaluate the consequences of the optimisations on the vehicle, several criteria have to be
analysed. The criteria are classified in the topics passive and active safety, lightweight
design, structural requirements and others. An overview of the criteria is shown in Fig. 7-1.
Passive safety:
• Good self protection performance
Structural
requirements:
• Good partner protection performance
• Easy reparability
• Good pedestrian protection performance
• Good corrosion
resistance
Active safety:
• Easy handling of towing
device
• Good visability through screens
• Good indirect vision
• Good visability by lighting installation
• Easy application of driver assistance
systems
Lightweight design:
• Low weight
• High weight saving by functional integration
• Additional weight reduction strategies
Others:
• Good operability
• High freedom of design
(branding)
• High degree of
innovation
• Effective engine cooling
• Compliance of max. axle loads
Fig. 7-1:
Evaluation criteria
In the next steps the criteria are ranked for importance on 40 t-HGVs. Therefore all criteria
are compared with each other as described in Fig. 7-2. If both criteria have the same
relevance, the rating is 1. If the criterion in the column is more important than the one in the
line, the rating is set to 0. If the criterion in the line is the more important one, the rating is 2.
The sum of each criteria line results in a ranking shown in Fig. 7-3. The criteria with the
highest points have a very high importance for the evaluation of the new structure. Overall
five classes are used to evaluate the different criteria. As shown in Fig. 7-3 the compliance of
the axle loads and safety requirements are the most important criteria for the technical
evaluation of the new truck front shape. Some of the important criteria can be evaluated by
the simulation results. Others are investigated in the following.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Fig. 7-2:
Good self protection performance
Good partner protection performance
Good pedestrian protection performance
Easy reparability
Low weight
High weight saving by functional integration
Additional weight reduction strategies
Compliance of max. axle loads
Good operability
Good visability through screens
Good indirect vision
Good corrosion resistance
High freedom of design (branding)
High degree of innovation
Easy application of driver assistance systems
Good visability by lighting installation
Effective engine cooling
Easy handling of towing device
Easy reparability
Low weight
High weight saving by functional integration
Additional weight reduction strategies
Compliance of max. axle loads
Good operability
1
1
0
0
0
0
0
2
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
2
0
1
0
0
0
0
0
0
0
0
2
1
0
0
0
0
2
0
1
0
0
0
0
0
0
0
0
2
2
2
2
2
2
2
2
2
2
1
1
1
1
2
2
0
2
2
2
0
1
1
2
1
2
2
0
0
1
1
2
1
0
2
2
2
0
1
1
2
1
2
2
0
0
1
1
2
1
0
2
2
2
0
1
1
2
1
2
2
0
0
1
1
2
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
2
2
2
0
1
1
1
1
1
1
0
0
0
0
1
1
0
10 11 12 13 14 15 16 17 18
1
1
1
0
0
0
0
2
1
1
0
0
0
0
1
1
0
2
2
2
0
0
0
0
2
1
1
0
0
0
1
1
1
0
2
2
2
1
2
2
2
2
2
2
2
1
1
2
2
2
0
2
2
2
1
2
2
2
2
2
2
2
1
1
2
2
2
1
2
2
2
1
1
1
1
2
2
2
2
1
1
1
2
2
0
2
2
2
1
1
1
1
2
2
2
1
0
0
1
1
1
0
2
2
2
0
0
0
0
2
1
1
1
0
0
0
1
1
0
2
2
2
0
1
1
1
2
1
1
1
0
0
0
1
1
Easy handling of towing device
9
Effective engine cooling
8
Good visability by lighting installation
7
Easy application of driver assistance systems
6
High degree of innovation
5
High freedom of design (branding)
4
Good corrosion resistance
3
Good indirect vision
2
Good visability through screens
1
Good pedestrian protection performance
Pairwise comparison of the criteria
90
Good partner protection performance
Technical Assessment
Good self protection performance
7
2
2
2
2
2
2
2
2
2
2
2
2
1
2
2
2
2
0
Pairwise comparison of the criteria
Evaluation
compliance of max. axle loads
good crash performance (self protection)
good crash performance (partner protection)
good crash performance (pedestrian protection)
good visability through screens
good indirect vision
good visability by lighting installation
good operability
effective engine cooling
low weight
high weight saving by functional integration
additional weight reduction strategies
easy application of driver assistance systems
high degree of innovation
easy reparability
good corrosion resistance
high freedom of design (branding)
easy handling of towing device
Fig. 7-3:
Ranking of the criteria
very high importance
high importance
medium importance
importance
low importance
7
Technical Assessment
91
To ensure sufficient lighting installation a possible set up for the reference tractor and the
optimised tractor is shown in Fig. 7-5. The optimised concept does not require any special
changes in lighting installation and functional areas for lighting installation are arranged. For
that reason there are no disadvantages to expect compared to the reference truck. All
requirements can be completely fulfilled.
Reference tractor
Indicator lamp
(category 1)
Indicator lamp
(category 1)
Main-beam
headlamp
Main-beam
headlamp
Dipped-beam
headlamp
Dipped-beam
headlamp
Front
reflector
End-outline
parking lamp
Fig. 7-4:
Advanced concept
Front reflector
Indicator lamps
(category 5 or 6)
End-outline
parking lamp
Indicator lamps
(category 5 or 6)
Possible lighting installation
A lateral view of the reference truck and the optimised concept with the downward vision
lines is shown in Fig. 7-5. Since there are no changes in positioning of the driver’s seat, the eye points also remain in the same position. The lower edge of the optimised concept’s windscreen is located further towards the front than reference truck’s windscreen edge. To provide the same downward vision angle the windscreen edge of the optimised concept is
lowered. Because of the extended front shape, the occultation area of the optimised concept
is smaller than the area of the reference truck.
Reference
truck
Advanced
concept
Fig. 7-5:
Direct visibility trough front screen
7
Technical Assessment
92
The lateral area of downward vision occultation is considered in Fig. 7-6. To improve the
direct vision in this direction the bottom side screen edges of the optimised concept are lower
than at the reference tractor. The figure shows that this leads to a smaller occultation area.
Reference
truck
Advanced
concept
Fig. 7-6:
Direct visibility trough side screens
The vision occultation in a top view can be seen in Fig. 7-7. The fields of occultation of the
two concepts are similar, because there are no variations of the seat position and also the Apillar position and rear side screen edges are similar. Furthermore even the reward indirect
vision performance is not modified, because the main mirrors setup is the same in both
concepts.
Reference
truck
Advanced
concept
Fig. 7-7:
Vision occultation in top view
7
Technical Assessment
93
Furthermore, it is apparent that the advanced concept offers more design space. To fulfil
future emission regulations, larger components, for example, for engine cooling and exhaust
after-treatment will be required. In this regard the advanced concept has advantages
compared to the reference truck as well.
7.1
Estimation of the Impact on Fatality Numbers in Europe
The investigation of HGV accident statistics leads to an estimated number of 2121 to 2298
fatally injured car occupants in truck to car accidents per year. Due to improved partner
protection performance that is proven in the simulation results, it can be expected that the
accident severity will be mitigated for this amount of car occupants. However, a big share of
these 2121 to 2298 fatalities is not avoidable, because they are attributable to high impact
velocities. A distribution of the impact velocities for the different accident scenarios is
currently not available in accident statistics.
Concerning fatal VRU accident with HGV involvement the total amount is estimated to 467 to
544. One reason for fatal injuries can be an overrun by the truck. The simulation results show
that an overrun can be prevented in all of the simulated cases. However, another important
factor that has an influence on the accident consequences is the initial contact between the
VRU and the truck front. The front must be soft enough, so the accident opponent can
survive this contact. Further detailed development of the advanced concept should aim to
meet the requirements for the initial contact between the truck front and VRUs.
For an estimation of a number of avoided VRU fatalities, the distribution of HGV impact
velocities in accidents with VRUs is required. It is illustrated in Fig. 7-8. In 40 to 50 % of all
fatal VRU accidents the truck velocity is below 40 km/h [WAN05, SIM05]. For the following it
is accepted that it is very unlikely to survive an accident with an impact speed higher than
50 km/h, so nearly 100 % of the fatal accidents happen with impact velocities less than this.
For impact velocities below 40 km/h it can be expected that a high percentage of fatalities
can be avoided, if the front structure is soft enough to survive the initial contact and an
overrun does not happen. However, not all fatalities will be prevented, because the
secondary contact between VRU and other objects like road users or any other obstacles in
the nearer surroundings cannot be avoided. This secondary contact can also be responsible
for fatal injuries. Hence it is assumed that 70 % of the fatalities in the lower velocities level
can be prevented. That way an optimistic estimation is calculated in Eq. 7-1 and the
pessimistic one in Eq. 7-2.
467  40%  70%  131
Eq. 7-1
544  50%  70%  190
Eq. 7-2
In the velocity level between 40 km/h and 50 km/h the percentage of avoided fatalities are
expected to be low due to the high impact speed. The estimation that 30 % of these fatalities
are preventable leads to a number of 232 to 296 avoided fatalities according to Eq. 7-3 and
Eq. 7-4.
7
Technical Assessment
94
131  (467  131)  30%  232
Eq. 7-3
190  (544  190)  30%  296
Eq. 7-4
100
90
Cumulative percentage [%]
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100
120
HGV impact velocity [km/h]
Fig. 7-8:
Distribution of HGV impact velocities in accidents with VRUs [SMI05]
Additionally, the improvement of the field of direct view can have a positive effect on the
number of killed VRUs. Because of the smaller occultation area of the advanced concept, the
probability that VRU are recognised in critical situations is greater, so accidents can be
prevented. Fig. 7-9 and Fig. 7-10 clarify this.
The improved downward vision can mainly improve impact on the scenarios 1, 4 and 5 from
Fig. 6-47. It is difficult to estimate the amount of lives saved, but the fact that in 47 % among
the accidents occurring on an intersection and involving at least one VRU blind spots from
the truck driver’s view are the main cause of the accident [IRU06], makes clear that positive
effects can be achieved.
The simulation results reveal that also for the truck occupants a mitigation of the accident
consequences is expected. But in this context it is important to mention that this group
exhibits a share of 50 % to 75 % of drivers who refuse to use a seat belt [DEK09]. It is
necessary to increase this percentage. The positive effect of the developed front shape of
the advanced concept can be utilised for drivers who are restrained properly.
7
Technical Assessment
95
VRU completely occluded
Reference
truck
VRU partly visible
Advanced
concept
Fig. 7-9:
Occultation of VRUs in side view
VRU completely occluded
Reference
truck
Advanced
concept
VRU partly visible
Fig. 7-10: Occultation of VRUs in front view
7.2
Weight Investigation
For a first estimation of the weight difference, the general structure and also the used
materials and manufacturing technologies for the advanced concept shall remain the same
as for the reference tractor. The weight changes as a result from changing the size and the
7
Technical Assessment
96
density of the respective parts. The weight increase because of the enlargement of the
windscreen as illustrated in Fig. 7-11. The investigation of the front covers and glazing are
explained in Fig. 7-11 and Fig. 7-12.
Reference tractor
Front
glazing
area: 2.0 m²
thickness:
5.5 mm
Advanced concept
Front
glazing
area: 3.0 m²
thickness:
5.5 mm
Weight increase: 12.3 kg
Fig. 7-11: Weight increase because of larger windscreen
Reference tractor
Advanced concept
Cooling cover
PP GF 30
area: 2.25 m²
thickness:
5.5 mm
Cooling cover
PP GF 30
area: 2.25 m²
thickness:
5.5 mm
Front bumper
cover
PP GF 30
area: 2.73 m²
thickness:
6.0 mm
Front bumper
cover
PP GF 30
area: 1.83 m²
thickness:
6.0 mm
Weight reduction: 6.01 kg
Fig. 7-12: Weight reduction because of smaller front cover
The crash management system’s weight is 60.7 kg. The standard steel bumper system’s weight is 53.6 kg. Since the crash management system replaces the steel bumper system, a
further weight increase of 7.1 kg is caused by the advanced concept. All in all, the mentioned
measures result in a total weight increase of 13.39 kg. To compensate this added weight
lightweight design measures are considered. Fig. 7-13 shows the qualitative cost of
lightweight design. It reveals that the usage of carbon fibre reinforced plastic (CFRP) enables
high weight savings, but high expenses are incurred due to this. In contrast, aluminium
7
Technical Assessment
97
applications lead to a lower increase of production cost, but also the achievable weight
reduction is lower.
The compensation of the added 13.39 kg of the changed tractor front can be realised by
easy measures. For this reason the most cost efficient measures are considered. This
means that aluminium parts which are easily applicable to the tractor by exchanging parts
without any changes of the basal construction are investigated.
One example for such a measure is the usage of an aluminium fifth-wheel plate instead of a
conventional steel device. This way a mass reduction between 33 kg (37 %) to 45 kg is
possible. If the slider combination beneath it is also modified and adapted a reduction of
even 58 kg is achievable.
Vehicle weight
low
high
Steel
high
Production cost
€/kg
low
Today
Future
Fig. 7-13: Cost of lightweight design [GOE09]
Fig. 7-14: Aluminium fifth-wheel plate
Furthermore, aluminium wheels are an option to reduce weight. For a tractor with six wheels
a total weight reduction of 120 kg can be realised, but the high cost of about 3000 € avoid a 7
Technical Assessment
98
higher market penetration. Furthermore aluminium wheels are more damageable as steel
wheels when assembling the tyre.
Fig. 7-15: Aluminium wheel
7.3
Evaluation
After considering these points and the simulation results, the concept evaluation can be
executed as shown in Fig. 7-16. To plot the result each evaluation value is multiplied by the
according criterion ranking. After this all multiplied values are summed up. In total the
reference truck reaches 306 evaluation points whereas the optimised concept reaches 426
points. The percentage result is shown in Fig. 7-17.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Evaluation criteria
Good self protection performance
Good partner protection performance
Compliance of max. axle loads
Good pedestrian protection performance
Good visability through screens
Good indirect vision
Good visability by lighting installation
Low weight
High weight saving by functional integration
Additional weight reduction strategies
Good operability
Easy application of driver assistance systems
Effective engine cooling
Easy reparability
Good corrosion resistance
High degree of innovation
High freedom of design (branding)
Easy handling of towing device
Fig. 7-16: Technical concept assessment
Rating
5
5
5
5
4
4
4
3
3
3
3
3
3
2
2
2
1
1
Advanced concept
Fulfillment of the criteria: 0,1,3,9
0: criteria not fulfilled
1: criteria less fulfilled
3: criteria partially fulfilled
9: criteria completely fulfilled
Reference truck
Fulfillment of the evaluation criteria
1
3
3
9
1
1
9
9
9
3
3
9
9
9
3
3
0
3
9
2
9
9
9
9
3
9
9
9
3
3
3
9
9
3
9
9
9
3
Technical Assessment
Percentage [%]
7
99
70
60
50
40
30
20
10
0
Reference Advanced
truck
concept
Fig. 7-17: Result of technical Assessment
8
Environmental and Economic Assessment
8
Environmental and Economic Assessment
100
For the evaluation of the different criteria in the environmental and technical assessment, the
same approach as in the technical assessment is used. The criteria are classified in the
environmental aspects, economic aspects concerning production as well as economic
aspects concerning the total cost of ownership. An overview of the criteria is shown in
Fig. 8-1.
Economic aspects (production):
• High production numbers
• Low variety of components
• Low material cost
• Low investment cost
• Low manufacturing cost
Economic aspects (total cost of
ownership):
• Low tractor purchase price
• Low fuel cost
• Low cost for insurance
• Low cost for taxes and toll
• Low joining cost
Environmental aspects:
• High modularisation
• Low fuel consumption by
aerodynamic measures
• High degree of automation
• Easy usage of available
manufacturing facilities
Others:
• Low fuel consumption by nonaerodynamic measures
• Low emissions
• Good recyclability
• Comfortable interior concept
(driving and resting)
• Reduction of injuries and fatalities
in road traffic
• Impression of exterior styling
Fig. 8-1:
Evaluation criteria
Again the criteria are ranked for importance on 40 t-HGVs with the same rating as in the
technical assessment (Fig. 8-2). The overall rating with a subdivision in five classes is shown
in Fig. 8-3. The most important criterion on the environment is again a safety aspect with the
reduction of injuries and fatalities in road traffic. This criterion is followed by the reduction of
fuel consumption and emissions.
Fig. 8-2:
Low joining costs
High modularisation
High degree of automatisation
Easy usage of available manufacturing facilities
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
2
1
1
0
1
1
1
1
1
0
1
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
1
1
2
0
0
0
0
0
0
0
0
1
1
2
1
15
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
1
1
1
1
1
1
1
1
1
2
2
2
2
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
0
2
2
1
2
0
2
2
2
0
0
2
0
2
2
0
2
1
1
1
1
1
1
1
1
0
1
2
2
2
1
1
1
1
1
1
1
2
2
2
2
1
1
1
1
1
1
1
2
2
2
1
1
1
1
1
1
2
2
2
1
1
1
1
1
2
2
2
1
1
1
1
2
2
2
1
0
1
2
2
2
1
2
2
2
2
1
1
1
1
1
1
1
0
0
1
2
2
2
2
2
2
2
2
1
2
1
2
2
2
2
2
2
2
2
2
2
1
2
1
2
2
1
2
1
2
1
1
2
1
2
1
1
2
1
2
1
1
2
1
2
1
1
2
1
2
1
1
2
1
2
1
1
2
1
2
1
1
2
1
2
1
1
1
1
2
1
1
2
0
2
0
0
1
0
2
0
0
2
0
2
0
0
2
0
2
0
0
1
0
2
0
0
Pair wise comparison of the criteria
Evaluation
reduction of injuries and fatalities in road traffic
low fuel consumption by aerodynamic measures
low fuel consumption by non -aerodynamic measures
low fuel costs
low emissions
low costs for insurance
low costs for taxes and toll
comfortable interior concept
low tractor purchase price
easy usage of available manufacturing facilities
high production numbers
high modularisation
low material costs
Impression of exterior styling
low variety of components
low investment costs
low manufacturing costs
low joining costs
high degree of automatisation
good recyclability
Fig. 8-3:
Ranking of the criteria
16 17 18 19 20
Impression of exterior styling
Low manufacturing costs
1
1
14
Comfortable interior concept
Low investment costs
1
10 11 12 13
Reduction of injuries and fatalities in road traffic
9
Low costs for taxes and toll
8
Low costs for insurance
7
Low fuel costs
6
Low tractor purchase price
5
Good recyclability
16
17
18
19
20
4
Low emissions
15
3
Low fuel consumption by non-aerodynamic
measures
14
High production numbers
Low variety of components
Low material costs
Low investment costs
Low manufacturing costs
Low joining costs
High modularisation
High degree of automatisation
Easy usage of available manufacturing facilities
Low tractor purchase price
Low fuel costs
Low costs for insurance
Low costs for taxes and toll
Low fuel consumption by aerodynamic
measures
Low fuel consumption by non-aerodynamic
measures
Low emissions
Good recyclability
Reduction of injuries and fatalities in road traffic
Comfortable interior concept
Impression of exterior styling
2
Low fuel consumption by aerodynamic
measures
1
2
3
4
5
6
7
8
9
10
11
12
13
1
Low material costs
Pairwise comparison of the criteria
101
Low variety of components
Environmental and Economic Assessment
High production numbers
8
1
0
2
0
0
0
2
0
0
2
2
2
0
0
1
8
Environmental and Economic Assessment
102
Important criteria are investigated in the following. Others can be evaluated considering the
simulation results.
One criterion to asses is the interior space of two concepts. The interior layout is an
important factor, because truck drivers spend a lot of time inside the cabin. Hence it should
be as comfortable as possible for driving and for resting as well. The cubage of the reference
tractor cabin is 11.292 m3. The advanced concept provides 11,762 m3 of interior space as
shown in Fig. 8-4. Due to this the design possibilities are more extensive for the advanced
concept.
11.292 m3
Fig. 8-4:
11.762 m 3
Interior space of reference truck an advanced concept
An additional important point that needs to be considered for the introduction of the
advanced concept is the impression of the exterior styling. The styling of new vehicle
concepts shall not be too futuristic or seem strange to possible costumers. For that reason
photo realistic renderings of the advanced concept are prepared. Three examples can be
seen in Fig. 8-5 and Fig. 8-6. Though the exterior styling cannot be assessed objectively the
images show that the basic concept design does not disable an appealing exterior styling.
Fig. 8-5:
Photo-realistic renderings
8
Environmental and Economic Assessment
Fig. 8-6:
Photo realistic rendering
8.1
Cost Estimation
103
A cost estimation is executed to evaluate the cost efficiency of the optimised concept.
Therefore the total costs of ownership (TCO) are investigated. The distribution of the total
cost of ownership can be seen in Fig. 8-7.
Driver
28.3 %
Operation
42.2 %
Tax/
Insurance
11.3 %
Investment
14.7 %
Fig. 8-7:
Service
3.5 %
Distribution of total cost of ownership (TCO) [TGX10]
8
Environmental and Economic Assessment
104
For the estimation the following boundary conditions are accepted. The average service life
of a haulage vehicle is 4 years. The annual mileage is valued at 125000 kilometres with an
average fuel consumption of 31.1 l/100 km [HEL05].
To figure out the effect of the cD value reduction on the fuel consumption simulations are
executed. Therefore a Matlab/Simulink is build up. Fig. 8-8 shows the structure of the used
model.
The drivetrain data are selected due to typical state of the art tractors. The internal
combustion engine power is assumed at 320 kW at 1800 rpm. The transmission data are
derived from typical 16 gear truck gearboxes. The cD value for the simulation basis is
calculated by CFD simulations of the reference truck to 0.703. Also the cross-sectional area
of 10.42 m is calculated using the CFD model of the reference truck.
Input
Simulation Model
Output
v [km/h]
120
80
40
0
0
100
200
300
400
500
600
700
800
900
1000
900
1000
T [Nm]
100
0
ICE
EM
-100
-200
0
100
200
300
400
500
600
700
800
n [rpm]
6000
2000
SOC [%]
0
Speed and
Load Profile
ax 
Fig. 8-8:
Fdem  FZ  p  fR   c w  A 
e i  mF  m Zu 
ICE
EM
4000
70
68
66
64
62
60
58
0
100
200
300
400
500
600
700
800
900
1000
0
100
200
300
400
500
t [s]
600
700
800
900
1000
L 2
v
2
Fuel consumption simulation model in Matlab/Simulink
The reference route used for the simulations is displayed in Fig. 8-9. This route leads from
Aachen to Cologne and back. The associated velocity and altitude profiles can be seen in
Fig. 8-10 and Fig. 8-11. The profiles are measured in test drives, so they represent realistic
driving scenarios. Due to this it can be seen that there are also time periods, in which the
truck is travelling with low speeds because of traffic volume for example.
8
Environmental and Economic Assessment
105
Start/Finish
Fig. 8-9:
Reference Route: Aachen - Cologne - Aachen
100
90
80
Velocity [km/h]
70
60
50
40
30
20
10
0
0
1000
2000
3000
Time [s]
Fig. 8-10: Velocity Profile
4000
5000
6000
7000
8
Environmental and Economic Assessment
106
240
SRTM
GPS
Altitude difference =
661 m
220
200
180
Hoehe [m]
Absolute 160
altitude
[m]
140
120
100
80
60
40
0
50
Strecke [km]
Distance
[km]
100
150
Fig. 8-11: Altitude Profile
Three different vehicle masses are considered in the simulations, one fully loaded vehicle
with 40 t, one partly loaded with 25 t and an empty one with 17 t. Fig. 8-12 shows the results
of the simulations. The relation between the chance of cD value and fuel consumption is
linear.
Δ f uel consumption [%]
8
6
4
2
0
Vehicle
-15
mass
-10
-5
-2 0
40t
-4
25t
-6
17t
-8
Fig. 8-12: Result of fuel consumption simulations
Δ c D [%]
5
c D= 0.703
10
15
8
Environmental and Economic Assessment
107
The optimised concept has a cD value of 0.618, which is a reduction of 12.11 % compared to
the reference basis. This leads to the reductions in fuel consumption that are listed in
Fig. 8-13.
Vehicle mass
Reduction of fuel consumption
40 t
3.20 %
25 t
4.43 %
17 t
5.29 %
Fig. 8-13: Reduction of fuel consumption for different vehicle masses
For the calculation of the fuel savings and the according cost saving only a fully loaded
vehicle is considered, because this reflects the minimum of savings that will be achieved in
any case. If a vehicle is partly travelling with fewer loads, the savings will be accordingly
higher than the calculated values. Fig. 8-14 shows the annual fuel savings for a vehicle with
a mass of 40 t. The column representing the accepted annual kilometrage of 125,000 km is
highlighted.
To translate the fuel savings into cost savings information about the fuel price are required.
Fig. 8-15 shows diesel prices for several European countries. The average price is 1.16 € per litre. The development of the diesel prices shows a rising tendency. As an example the price
development in Germany can be seen in Fig. 8-16. These numbers were collected in 35th
calendar week of the year 2010.
Fuel savings [l/a]
2.000
1.500
1.000
500
0
1.244
1.493
1.742
125.000
150.000
175.000
Annual kilometrage [km]
Fig. 8-14: Annual fuel savings
8
Environmental and Economic Assessment
108
Bulgaria
0.97
European average
1.16
Luxemburg
0.99
Hungary
1.16
Lithuania
1.02
Portugal
1.17
Malta
1.06
Belgium
1.17
Cyprus
1.06
Slovenia
1.18
Latvia
1.06
Switzerland
1.2
Poland
1.07
Denmark
1.21
Romania
1.07
Germany
1.21
Spain
1.08
Italy
1.21
Estonia
1.11
Czech Republic
1.24
Austria
1.11
Ireland
1.25
Finland
1.12
Sweden
1.26
Slovakia
1.13
Greece
1.27
France
1.14
Great Britain
1.44
Netherlands
1.15
Norway
1.45
0.8
1
1.2
1.4
Diesel price [€]
1.6
0.8
1
1.2
1.4
Diesel price [€]
1.6
Fig. 8-15: Diesel prices in European countries [AVD10]
160
140
Diesel price
120
100
80
60
40
20
0
2002
2003
2004
2005
2006
2007
Year
Fig. 8-16: Diesel price development in Germany [ARA10]
2008
2009
2010
8
Environmental and Economic Assessment
109
To achieve a realistic estimation for the near future a diesel price of 1.25 € (excluding VAT) is
accepted. This price considers the European average and also the tendency. Inquiries of
forwarding agencies show that in many cases contracts between the enterprises and the oil
companies even reduce the price. The accordant cost savings are shown in Fig. 8-17, again
for three different annual kilometrage scenarios.
2.500
Cost savings [€]
2.000
1.500
1.000
500
0
1.555
1.866
2.177
125.000
150.000
175.000
Annual kilometrage [km]
Fig. 8-17: Cost savings resulting from fuel savings
After the estimation of cost savings resulting from a fuel efficiency increase the changes of
production cost are investigated. Analogous to the weight estimation the general structure
and also the used materials and manufacturing technologies for the optimised concept shall
remain the same as for the reference tractor in the first approach. The changes in cost result
from changing the size of the respective parts. The area of the windscreen is calculated in
subchapter 7.2. The additional size of the windscreen of the optimised concept causes a cost
increase of 22.50 €. Similar investigations are also executed for the cooler cover and the
front bumper cover. The cooler cover remains at the same size. The front bumper cover can
be designed smaller than the one used for the reference tractor. It is assumed that the
covers for both concepts are made from PP GF 30 plastics material, which is a standard
material for such applications. Due to this there is a cost reduction of 12.02 €. Since an exact
calculation of the CMS cost is not possible without detailed knowledge of many different
parameters like production numbers, production process or integration of secondary parts,
the cost estimation will be approximated by the weight of the part. Result of enquiries on that
question is that the price of a part can be approximated by an average value of 5 to 6 Euros
per kilo. The weight of the crash management system is 60.7 kg. That leads to an amount of
364.20 €. In total all these measures to extend the vehicle front lead to an increase of
production cost of 398.72 €.
8
Environmental and Economic Assessment
110
However, it should be noted that this approach would lead to a weight increase of 13.39 kg.
But because this weight increase is relatively low in comparison with the overall weight of the
tractor, the cost for weight reduction measures are neglected.
To estimate the feasible investment for research and development (R & D) for the manufacturers to achieve series-production readiness of the advanced concept, a depreciation
period of four years is considered. The investigation of the running cost revealed that the
advanced concept causes at least 1555 € of fuel saving. Considering a discounting of annual
savings of 4 % the total cost savings sum up to 5870.27 € as shown by Eq. 8-1.
1555 €  1555 € / 1.04  1555 € / 1.04 2  1555 € / 1.04 3  5870.27 €
Eq. 8-1
After subtraction of the additional cost of 398.72 € the generated benefit is 5471.55 € per unit sold. This amount of money can be utilised for R & D. However no customer benefit would be
generated this way. Manufacturers also often consider a depreciation period of two years.
For this time period the feasible R & D cost can be calculated analogous to the previous
calculation. For this case the generated benefit per unit is 2651.47 €.
The reduction of CO2 emissions is illustrated in Fig. 8-18. This estimation is executed
according to the fuel savings. As a basis for this calculation an emission of 2.65 kg CO2 per
combustion of 1 litre diesel is assumed.
CO2-reduction [kg/a]
5.000
4.000
3.000
2.000
1.000
0
3.297
3.956
4.615
125.000
150.000
175.000
Annual kilometrage [km]
Fig. 8-18: CO2-Reduction according to fuel savings
For an estimation of the reduction of CO2 emissions across Europe kilometrage data for
several European countries are aggregated in Fig. 8-19.
8
Environmental and Economic Assessment
Country
Million kilometres per
year
111
Country
Million kilometres per
year
Austria
1476
Ireland
619
Belgium
1836
Italy
385
Bulgaria
763
Latvia
424
Cyprus
39
Lithuania
765
Czech Republic
2398
Luxemburg
496
Denmark
1175
Netherlands
5145
Estonia
292
Poland
8641
Finland
1113
Portugal
1813
France
12679
Romania
1060
Germany
17910
Slovakia
1351
Great Britain
7614
Slovenia
823
Greece
619
Spain
10462
Hungary
1757
Sweden
1445
Sum
86077
Fig. 8-19: Kilometrage of 40 t vehicles in Europe [EUR10]
For the estimation again an average fuel consumption of 31.1 l/100 km is assumed [HEL05].
The calculated reduction of fuel consumption of 3.20 % in the worst case leads to a total fuel
saving of about 856 million litres per year and an according reduction of CO2 emissions of
approximately 2.3 million tons per year. In the best case a reduction of fuel consumption of
5.30 % could be possible. This would save 1.4 billion litres fuel per year and cause a
reduction of CO2 emissions of approximately 3.8 million tons. Compared to the overall
emissions of 962 million t CO2 caused by road traffic this means a reduction of 0.24 % (worst
case) to 0.40 % (best case) [EUR10].
8.2
Evaluation
After considering simulation results and the previously described estimations the assessment
is executed. The individual evaluations are summarised in Fig. 8-20. The assessment results
can be seen in Fig. 8-21.
Environmental and Economic Assessment
112
Reference truck
Fulfillment of the evaluation criteria
Fulfillment of the criteria: 0,1,3,9
0: criteria not fulfilled
1: criteria less fulfilled
3: criteria partially fulfilled
9: criteria completely fulfilled
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Evaluation criteria
High production numbers
Low variety of components
Low material costs
Low investment costs
Low manufacturing costs
Low joining costs
High modularisation
High degree of automatisation
Easy usage of available manufacturing facilities
Low tractor purchase price
Low fuel costs
Low costs for insurance
Low costs for taxes and toll
Low fuel consumption by aerodynamic measures
Low fuel consumption by non-aerodynamic
measures
Low emissions
Good recyclability
Reduction of injuries and fatalities in road traffic
Comfortable interior concept
Impression of exterior styling
Rating
2
1
1
1
Fig. 8-20: Environmental and economical concepts assessment
Percentage [%]
70
60
50
40
30
20
10
0
Reference
truck
Advanced concept
8
Advanced
concept
Fig. 8-21: Results of environmental and economical assessment
1
1
2
1
2
2
4
3
3
4
4
4
1
5
1
1
1
2
3
3
9
9
9
9
3
1
9
9
1
3
9
1
3
3
3
3
9
9
3
1
9
3
9
9
9
9
1
1
1
1
3
3
3
3
9
3
9
9
9
Recommendations
9
Recommendations
113
The results of this study show that significant reductions of fuel consumption and an
improvement of road safety are achievable by changing the front of trucks. To achieve these
targets changes in legislation regarding the maximum dimensions, material usage and direct
field of view are required.
9.1
Design Space
To reduce the fuel consumption and increase the road safety of trucks a length extension of
the front part of the tractor is necessary. Hence the limit for an overall length of 17.3 m is
suggested in this study. An important point is that this extension should not be used to
increase the cargo space, but to create a rounded aerodynamic front shape. Due to this, the
length limitation for trailers should not be changed.
Furthermore the rounding of the front should be assured by the arranged design space of
future regulations. For this purpose an examination geometry is defined. This geometry is
described by two circles. The first one is located on the street plane. It has a radius of
1.48 m. The centre point is on the centre plane of the vehicle. The second circle is positioned
on the centre plane. It has a radius of 6.45 m. The centre of this circle is located on the street
plane. Both circles intersect at a reference point that is located 5 cm in front of the foremost
point of the tractor on the street plane and on the centre plane of the vehicle. Fig. 9-1
explains the position of the two circles. The position of the reference point is shown in
Fig. 9-2.
r ≤ 6.45 m
Reference point
on the ground
≤ 17.3 m
≤ 17.3 m
r ≤ 1.48 m
Fig. 9-1:
Description of examination geometry
The two circles span a surface in front of the tractor. This surface shall not be pierced by any
part of the tractor. The surface of the examination geometry can be seen in Fig. 9-3.
9
Recommendations
114
Length
limitation
r ≤ 6.45 m
Reference
point
≤ 17.3 m
≤ 17.35 m
Fig. 9-2:
Length limitation and position of reference point for examination geometry
Fig. 9-3:
Examination geometry
To implement these suggestions in future regulations the following changes are
recommended:
9
Recommendations
115
1. Total length limit shall be raised in 96/53/EC, ANNEX 1, point 1.1: Change “16.50 m” to “17.30 m”.
2. An additional point shall be integrated into 96/53/EC, ANNEX 1, point 1.1: No point of
the vehicle shall project beyond an examination geometry that is defined as follows:
a. Two circles span the surface of the examination geometry.
b. The first circle is located on the street plane. The radius of the circle is 1.45 m.
The centre point is located on the centre plane of the vehicle.
c. The second circle is located on the centre plane of the vehicle. The radius of
the circle is 6.45 m. The centre point is located on the street plane.
d. Both circles intersect at a reference point. This point is located 5 cm in front of
the foremost point of the vehicle in the street plane and in the centre plane of
the vehicle.
9.2
Material Usage
The initial contact between the truck front and a VRU in case of an accident has big influence
on the accident consequences. Hence an energy absorbing zone is required. Regarding the
head impact the minimal energy absorption length should be 68 mm to assure that limiting
values are not exceeded [KÜH07]. Therefore a zone of this length behind all non transparent
exterior parts on the front should be reserved for energy absorbing materials.
9.3
Direct Vision
The suggested design changes may not result in an aggravation of the direct vision of the
truck driver. To achieve this it is recommended to work out a regulation for the direct field of
view of trucks similar to the ECE-R 125 that currently only applies for passenger cars.
10
Summary and Outlook
10
Summary and Outlook
116
The main requirements for trucks are to provide a maximum of cargo space and to carry a
maximum of payload. The upper limits for these values, e.g. an overall length of 16.5 m
length and 40 t of gross weight, are set by current European Union Regulations. These
boundary conditions lead to a flat front design of tractors that has disadvantages regarding
safety and aerodynamic issues. The focus of this study is to analyse, what benefits regarding
fuel consumption and safety can result from rounding the front shape of tractors. The
required design space for this was provided by an increase of the maximum semi-trailer
combination length.
As a basis for the study, an analysis of state-of-the-art semi-trailer tractors, close to series
concept trucks and future design concepts was executed. In addition regulations and
directives with regard to the design of the truck front were investigated. The key learnings
from that were used for the build-up of a generic CAD model of a reference truck. After this,
three optimised base concepts were derived. The base concepts had different length
extensions of 400 mm, 800 mm and 1200 mm. In the 800 mm and the 1200 mm extended
concept also the position of the front axle and the entrance steps was re-arranged, to assure
a sufficient approach angle and comfortable ingress and egress. A pre-assessment of these
base concepts concerning aerodynamic performance, compliance of axle loads and
manoeuvrability revealed that the 800 mm extended concept forms the best compromise.
Due to this it was selected to undergo a second optimisation loop to further improve its
aerodynamic properties. Finally, an improvement of the cD value of more than 12 %
compared to the reference truck was proven in CFD simulation. This effects a reduction of
fuel consumption by 3.2 % to 5.3 % depending on the gross weight of the vehicle. If this
reduction of fuel consumption is associated to overall annual fuel consumption of HGVs a
total saving of 856 to 1400 million litres of fuel and 2.3 to 3.8 million tons of CO2 emissions
accordingly can be achieved.
Crash simulations showed that the rounded front shape has advantages in terms of safety.
Three load cases were defined for this reason. First, simulations of accidents involving
pedestrians and cyclist were executed. It was observed that the rounded front shape of the
advanced concept has a deflective effect for pedestrians after the initial contact in an
accident. For this reason an overrun of the accident partner was prevented in 100 % of the
advanced concept simulations, whereas simulations of the reference model lead to an
overrun in 70 % of the simulated cases. In the second load case the tractor crashed into a
trailer standing in front of it to reproduce the accident scenario of a truck hitting another truck
from behind. These simulations revealed that the advanced concept provides an enhanced
self protection performance. Intrusions at the tractors front were reduced by approximately
40 mm. The third load case was set up to evaluate the partner protection performance. In a
scenario of a passenger car hitting the tractor frontally, higher intrusions into the car
compared to the reference were detected. This occurs, because the initial contact area of the
car and the front of the advanced concept is smaller than the contact area of the car and the
reference tractor front, which leads to higher local loads and an uneven absorption of the
10
Summary and Outlook
117
crash energy. Hence an additional crash management system was applied to the free design
space in the front of the advanced concept. By means of this system the intrusions were
reduced below the reference values, so the partner protection performance was improved.
This study shows that changes of current regulations can lead to a significant improvement
of efficiency and road safety of trucks. For that reason recommendations with regard to
future legislation based on the results of the investigations were derived.
The presented results base on a holistic approach. Due to this the level of detail is limited in
some points of the analysis. It is preferable to execute further researches to fully realise the
disclosed potential. A more detailed investigation of the crash management system, for
example, can result in additional enhancement of the crash behaviour. Furthermore it should
be examined whether further refinement of the vehicle front can determine supplemental
increase of efficiency.
11
Formula Symbols and Indices
11
Formula Symbols and Indices
cD
Aerodynamic drag coefficient
cT
Tangential force coefficient
GTractor Weight force of the tractor
GTrailer Vertical trailer load on the fifth-wheel plate
FFront
Front axle load of the tractor
FRear
Rear axle load of the tractor
lWB
Wheelbase of the tractor
lTractor Distance between the centre of gravity of the tractor and its rear axle
lTrailer
Distance between the centre of gravity of the tractor and its fifth-wheel plate
r
Curvature radius
118
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[LAS03]
N. N.
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N. N.
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[MAI09]
MAIERHOFER, B.
Der 1-Liter LKW
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[MAN09]
N. N.
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[MES06]
MESINA, C. T., et al
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[MEK10]
N. N.
Field of vision
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[MOT11]
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[SCA02]
N. N.
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[SCA10]
N. N.
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[SCB10]
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[SCH06]
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[SMI05]
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[VOL10b] N. N.
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129
13
Appendix
13
Appendix
13.1
130
CFD Simulations
Reference truck
Concept 1
30
30
15
velocity [m/s]
15
velocity [m/s]
Concept 2
Concept 3
30
15
velocity [m/s]
Advanced concept
30
15
velocity [m/s]
Fig. 13-1: Velocity in the streamlines
30
15
velocity [m/s]
13
Appendix
131
13.2
Partner Protection Simulations
13.3
Frontal Collision without Offset
Reference truck
Advanced concept
Intrusion
[mm]
180
140
100
60
20
0
Max = 175.9 mm
Max = 187.3 mm
Fig. 13-2: Intrusions into the car’s firewall after the crash
Rear seat left side
250
Rear seat right side
Acceleration [g]
200
150
100
50
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 13-3: Acceleration at the car’s rear seats during the crash with the reference truck
13
Appendix
132
250
Rear seat left side
Rear seat right side
Acceleration [g]
200
150
100
50
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 13-4: Acceleration at the car’s rear seats during the crash with the advanced concept
450
400
1
3
2
4
Force [kN]
350
300
250
200
150
100
50
0
0
20
40
60
80
Time [ms]
100
Fig. 13-5: Forces in the side members of the reference truck
120
140
160
13
Appendix
133
450
1
1
3
3
400
2
4
Force [kN]
350
300
250
200
150
100
50
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 13-6: Forces in the side members of the advanced concept
225
Total amount
of absorbed
energy
200
Energy [kJ]
175
Energy
absorbed
by car
150
125
Energy
absorbed
by truck
100
75
50
25
0
0
20
40
60
80
100
Time [ms]
120
Fig. 13-7: Energy absorption behaviour of reference truck
140
160
13
Appendix
134
225
Total amount
of absorbed
energy
200
Energy [kJ]
175
Energy
absorbed
by car
150
125
Energy
absorbed
by truck
100
75
50
25
0
0
20
40
60
80
100
Time [ms]
120
140
160
Fig. 13-8: Energy absorption behaviour of the advanced concept
13.4
Rear Shunt
Reference truck
Advanced concept
Intrusion
[mm]
-120
-90
-60
-30
0
Max = -80.2 mm
Max = -34.8 mm
Fig. 13-9: Intrusions into the car’s rear bottom panel
13
Appendix
135
Rear seat left side
200
Rear seat right side
Acceleration [g]
150
100
50
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 13-10: Acceleration at the car’s rear seats during the crash with the reference truck
Rear seat left side
100
Rear seat right side
Acceleration [g]
75
50
25
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 13-11: Acceleration at the car’s rear seats during the crash with the advanced concept
13
Appendix
136
150
Force [kN]
125
1
3
2
4
100
75
50
25
0
0
20
40
60
80
Time [ms]
100
120
140
160
Fig. 13-12: Forces in the side members of the reference truck
150
Force [kN]
125
1
3
2
4
100
75
50
25
0
0
20
40
60
80
Time [ms]
100
Fig. 13-13: Forces in the side members of the advanced concept
120
140
160
13
Appendix
137
40
Total amount
of absorbed
energy
35
Energy [kJ]
30
Energy
absorbed
by car
25
20
Energy
absorbed
by truck
15
10
5
0
0
20
40
60
80
100
Time [ms]
120
140
160
Fig. 13-14: Energy absorption behaviour of reference truck
40
Total amount
of absorbed
energy
35
Energy [kJ]
30
Energy
absorbed
by car
25
20
Energy
absorbed
by truck
15
10
5
0
0
20
40
60
80
100
Time [ms]
120
Fig. 13-15: Energy absorption behaviour of the advanced concept
140
160
13
Appendix
138
13.4.1
VRU Protection Simulations
13.4.2
Reference Tractor: Central Impact
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-16: Reference tractor against 6 year old child
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-17: Reference tractor against 5 % female
13
Appendix
139
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-18: Reference tractor against 95 % male
13
Appendix
140
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
780 ms
910 ms
1040 ms
1170 ms
1300 ms
1430 ms
Fig. 13-19: Reference tractor against cyclist
13
Appendix
13.4.3
141
Reference Tractor: Edge Impact
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-20: Reference tractor against 6 year old child
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-21: Reference tractor against 5 % female
13
Appendix
142
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-22: Reference tractor against 50 % male
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-23: Reference tractor against 95 % male
13
Appendix
13.4.4
143
Advanced Concept: Central Impact
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-24: Advanced concept against 6 year old child
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-25: Advanced concept against 5 % female
13
Appendix
144
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-26: Advanced concept against 95 % male
13
Appendix
145
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
780 ms
910 ms
1040 ms
1170 ms
1300 ms
1430 ms
Fig. 13-27: Advanced concept against cyclist
13
Appendix
13.4.5
146
Advanced Concept: Edge Impact
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-28: Advanced concept against 6 year old child
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-29: Advanced concept against 5 % female
13
Appendix
147
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-30: Advanced concept against 50 % male
0 ms
130 ms
260 ms
390 ms
520 ms
650 ms
Fig. 13-31: Advanced concept against 95 % male
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