Development and validation of eevc wg17 lower

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 02 Issue: 08 | Aug-2013, Available @ http://www.ijret.org 137
DEVELOPMENT AND VALIDATION OF EEVC WG17 LOWER
LEGFORM FE MODEL FOR PEDESTRIAN SAFETY
Khoo Y.C1
, F. Tarlochan2
1, 2
Center for Innovation and Design, College of Engineering, Universiti TenagaNasional, 43009 Selangor
Abstract
Vehicle-pedestrian collisions had claimed the lives of many in the world roads yearly. Among the types of injury that may occur in a
vehicle-pedestrian collision, lower extremity injuries have the highest account. These alarming statistic has encouraged joining effort
from researchers, car manufacturers and the government to find solutions in reducing the risk of vulnerable road users. The car
bumper structure design plays a crucial role in cushioning the impact on the pedestrian leg during a collision. The European
Enhanced Vehicle-Safety Committee (EEVC) has developed test methods to evaluate severity of the lower leg injury, upper leg injury
and head impact injury in a vehicle-pedestrian simulated collision. Since lower extremity injury are most common, undivided attention
should be paid on the lower legform to bumper test. The maximum bending angle, maximum shearing displacement and maximum
tibia acceleration are among the three injury criterion determined for lower legform to bumper test. Before the lower legform to
bumper test can be perform the lower legform has to be certified statically and dynamically.
The advancement of computerization had supported the usage of Finite Element Method(FEM) in simulating real life scenarios for
analysis. Irregular geometries are now discretized and solved numerically. Finite Element Analysis(FEA) has proven to reduce time
and cost significantly therefore the author took advantaged of this tool and simulated a lower legform to bumper collision. This paper
presents in detail the static and dynamic certification of the Finite Element (FE) legform model using the HyperWorks software. The
static results for both bending and shearing has to be within the EEVC/WG17 limits and the internal energy at 15º shall be 100±7J.
The maximum bending angle shall not be less than 6.2º and not more than 8.2º, the maximum shearing displacement shall not be less
than 3.5mm and not more than 6mm, and the maximum upper tibia acceleration shall not be less than 120g and not more than 250g in
the dynamic certification test.
Index Terms: Pedestrian Safety, Legform Impactor, EEVC WG17, Finite Element Analysis
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1. INTRODUCTION
World Health Organization (WHO 2013) reported that more
than 270 000 pedestrian in the world loses their lives on the
roads yearly. This amount contributes to 22 percent of the 1.24
million road traffic deaths around the world.[1] Millions of
pedestrians suffer serious injuries in traffic accident and some
unfortunate victims become permanently disabled. These
tragical injuries and deaths cause immeasurable heartache and
inconvenience to both family members and friends especially
individuals who are economically challenged. Globalization in
low and middle-income countries has led to an increase in
motorization, accounting to 52 percent out of 1.6 billion
globally registered vehicles[6]. The escalation in vehicle usage
contributes to a higher probability in the occurrence of
pedestrian-vehicle accident
The common injuries in a pedestrian-vehicle collision includes
dislocation of the pelvis, fracture of bones, torn of ligaments
and head damage. The International Harmonizes Research
Activities’ (IHRA) statistic has shown than 67.1 percent of the
lower extremities are caused by the car bumper, 12.1 percent
by the bonnet leading edge and 7.6 percent by the front panel
of the vehicle structure.[2] Due to the high percentage of
lower extremity injuries, considerable effort needed to be
focused on re-engineering the car bumper system to mitigate
pedestrian lower extremity injuries and hence the author will
focus on the lower leg . Injuries on the lower extremities
include fracture of the bones and a tear in any of the knee
ligaments i.e anterior cruciate ligament (ACL), posterior
cruciate ligament (PCL), lateral collateral ligament (LCL) and
medial collateral ligament (MCL) [7].
The alarming pedestrian fatalities statistic has raised global
awareness on pedestrian safety, prompting researchers and car
manufacturers to improve the current vehicle design. Many
government and independent agencies such as the European
New Car Assessment Program (Euro NCAP) , Japan New Car
Assessment Program (JNCAP), Japan Automobile
Manufacturers’ Association (JAMA), the Japan Automobile
Research Institute (JARI) and National Highway Traffic
Safety Administration (NHTSA) in the United States took the
initiative to perform crash test and in-depth research on
pedestrian protection.

IJRET: International Journal of Research in Engineering and Technology
__________________________________________________________________________________________
Volume: 02 Issue: 08 | Aug-2013, Available @
The basis of this study follows the test procedure proposed by
the European Enhanced Vehicle-Safety Committee Working
Group 17 Report (EEVC/WG17)EEVC (2002). A legform
impactor is a tool used to evaluate the severity of the leg
injury in a vehicle-pedestrian simulated collision. The EEVC
lower legform impactor consists of a deformable knee joining
two 70mm diameter rigid steel tubes that represents the tibia
and femur. The tubes are covered with 25mm CF
Foam representing flesh and 6mm Neoprene representing the
skin. The knee joint is capable of lateral bending and shearing.
The shearing displacement of the knee, bending angle of the
knee and the tibia acceleration are measured to evaluate the
severity of the injury. The shearing displacement is used to
evaluate cruciate ligament injuries, the bending angle is used
to evaluate collateral ligament injuries and the tibia
acceleration is used to evaluate the tibia fractur
The main objective of this study is to use Finite Element
Analysis (FEA) to simulate the static and dynamic
certification of the lower legform impactor according to the
EEVC/WG17 procedures.
2 EEVC/WG17 LOWER LEGFORM IMPACT
TEST
In this study, the author used the EEVC WG17 as a reference
to ensure the FE legform model complies with appropriate
performance requirements. Although the standard caters for
three test methods; legform to bumper test, upper legform to
bonnet leading edge test and the headform to bonnet top test,
the author will only focus on the legform to bumper test as this
is the only test that caters for injuries on the lower extremities.
The validation of the lower legform impactor consists of two
parts, which are the static test and the dynamic test. The static
test is further divided into knee bending test and knee shearing
test.
2. 1- STATIC TEST
2.1.1- Bending Test
A bending test set-up shown in Figure 1 is proposed in the
EEVC/WG17 whereby the tibia is being fully constrained. A
horizontal normal force is applied to the metal tube at a
distance of 2.0±0.01m from the center of the knee joint. The
corresponding knee bending angle was recorded and the load
shall be increased until the knee bending angle is in
22 degree. The energy taken to generate 15 degree of bending
shall not be more than 100±7J. According to the EEVC/WG17
report, the energy limit function to minimise variation in
performance of the deformable elements [3].
be calculated by integrating the force with respect to the
bending angle in radians, and by multiplying the lever length
of 2.0±0.01m. The corresponding knee bending angle
compiled and the applied force in Newton against the knee
IJRET: International Journal of Research in Engineering and Technology eISSN: 2319
__________________________________________________________________________________________
2013, Available @ http://www.ijret.org
The basis of this study follows the test procedure proposed by
Safety Committee Working
Group 17 Report (EEVC/WG17)EEVC (2002). A legform
tor is a tool used to evaluate the severity of the leg
pedestrian simulated collision. The EEVC
lower legform impactor consists of a deformable knee joining
two 70mm diameter rigid steel tubes that represents the tibia
bes are covered with 25mm CF-45 Confor
Foam representing flesh and 6mm Neoprene representing the
skin. The knee joint is capable of lateral bending and shearing.
The shearing displacement of the knee, bending angle of the
e measured to evaluate the
severity of the injury. The shearing displacement is used to
evaluate cruciate ligament injuries, the bending angle is used
te collateral ligament injuries and the tibia
acceleration is used to evaluate the tibia fracture risk[8].
The main objective of this study is to use Finite Element
Analysis (FEA) to simulate the static and dynamic
certification of the lower legform impactor according to the
2 EEVC/WG17 LOWER LEGFORM IMPACT
In this study, the author used the EEVC WG17 as a reference
to ensure the FE legform model complies with appropriate
performance requirements. Although the standard caters for
three test methods; legform to bumper test, upper legform to
test and the headform to bonnet top test,
the author will only focus on the legform to bumper test as this
is the only test that caters for injuries on the lower extremities.
The validation of the lower legform impactor consists of two
e static test and the dynamic test. The static
test is further divided into knee bending test and knee shearing
up shown in Figure 1 is proposed in the
EEVC/WG17 whereby the tibia is being fully constrained. A
horizontal normal force is applied to the metal tube at a
distance of 2.0±0.01m from the center of the knee joint. The
ending angle was recorded and the load
shall be increased until the knee bending angle is in excess of
22 degree. The energy taken to generate 15 degree of bending
According to the EEVC/WG17
to minimise variation in
performance of the deformable elements [3]. The energy can
be calculated by integrating the force with respect to the
bending angle in radians, and by multiplying the lever length
of 2.0±0.01m. The corresponding knee bending angle were
compiled and the applied force in Newton against the knee
bending angle in Degrees was plotted and compared with the
EEVC limitations [3].
Figure 1: Top view of test set
bending certification test
2.1.2- Shearing Test
Figure 2 shows the test set
The tibia was fully constrained while the femur was restraint
2.0m from the center of the knee joint. A horizontal normal
force was applied on the femur 50mm from the center of the
knee joint. The load shall be increased until the shearing
displacement of the knee reaches an excess of 8.0mm or the
load is in excess of 6.0kN. The correspo
displacement was recorded and plotted against the applied
force.[3]
Figure 2: Top view of test set
shearing certification test
2. 2- DYNAMIC TEST
For dynamic test certification, the legform impactor is with
foam and skin covering. It shall be suspended horizontally by
three wire ropes of 1.5±0.2mm diameter and of 2.0m
minimum length as shown in figure 3. The legform impactor
shall be suspended along its longitudinal
with a tolerance of ±2°. The total mass of the femur and tibia
shall be 8.6±0.1kg and 4.8±0.1kg respectively, and the total
mass of the legform shall be 13.4±0.2kg. The centre of gravity
of the femur and tibia shall be 217±10mm and 233±1
from the center of knee respectively. The moment of inertia of
the femur and tibia, about
respective centre of gravity and perpendicular to the direction
of impact, shall be 0.127±0.010kgm
A uniaxial accelerometer shall be mounted on the non
eISSN: 2319-1163 | pISSN: 2321-7308
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138
bending angle in Degrees was plotted and compared with the
Top view of test set-up for static legform impactor
bending certification test [3]
Figure 2 shows the test set-up for shearing of the certification.
The tibia was fully constrained while the femur was restraint
of the knee joint. A horizontal normal
force was applied on the femur 50mm from the center of the
knee joint. The load shall be increased until the shearing
displacement of the knee reaches an excess of 8.0mm or the
load is in excess of 6.0kN. The corresponding knee shearing
displacement was recorded and plotted against the applied
Top view of test set-up for static legform impactor
shearing certification test [3]
DYNAMIC TEST
certification, the legform impactor is with
foam and skin covering. It shall be suspended horizontally by
three wire ropes of 1.5±0.2mm diameter and of 2.0m
minimum length as shown in figure 3. The legform impactor
shall be suspended along its longitudinal axis horizontally
with a tolerance of ±2°. The total mass of the femur and tibia
shall be 8.6±0.1kg and 4.8±0.1kg respectively, and the total
mass of the legform shall be 13.4±0.2kg. The centre of gravity
of the femur and tibia shall be 217±10mm and 233±10mm
from the center of knee respectively. The moment of inertia of
the femur and tibia, about the horizontal axis through
respective centre of gravity and perpendicular to the direction
of impact, shall be 0.127±0.010kgm2 and 0.120±0.010kgm2.
celerometer shall be mounted on the non-

IJRET: International Journal of Research in Engineering and Technology
__________________________________________________________________________________________
Volume: 02 Issue: 08 | Aug-2013, Available @
impacted side of the tibia, 66±5mm below the knee joint
center. Refer to figure 5, for legform impactor with skin and
foam covering.
The certification impactor shall have a mass of 9.0±0.05kg,
the mass includes those propulsion and guidance components
which are effectively part of the impactor during the impact.
The dimension of the face of the certification impactor shall
be as specified in figure 6. The impactor shall be made of
aluminium alloy with an outer surface finish of better than
2.0µm. The certification impactor shall be propelled
horizontally at a velocity of 7.5±0.1m/s into a stationary
legform impactor as shown in figure 3 and 4.
When the legform impactor is impacted by a linearly guided
certification impactor, the maximum upper tibia acceleration
shall be not less than 120g and not more than 250g. The
maximum bending angle shall be not less than 6.2° and not
more than 8.2°. The maximum shearing displacement shall be
not less than 3.5mm and not more than 6.0mm
Figure 3: Side view-Test set-up for dynamic legform
impactor certification test [3]
Figure 4: Top view- Test set-up for dynamic legfo
IJRET: International Journal of Research in Engineering and Technology eISSN: 2319
__________________________________________________________________________________________
2013, Available @ http://www.ijret.org
impacted side of the tibia, 66±5mm below the knee joint
center. Refer to figure 5, for legform impactor with skin and
The certification impactor shall have a mass of 9.0±0.05kg,
those propulsion and guidance components
which are effectively part of the impactor during the impact.
The dimension of the face of the certification impactor shall
be as specified in figure 6. The impactor shall be made of
rface finish of better than
2.0µm. The certification impactor shall be propelled
horizontally at a velocity of 7.5±0.1m/s into a stationary
legform impactor as shown in figure 3 and 4.
When the legform impactor is impacted by a linearly guided
on impactor, the maximum upper tibia acceleration
shall be not less than 120g and not more than 250g. The
maximum bending angle shall be not less than 6.2° and not
more than 8.2°. The maximum shearing displacement shall be
than 6.0mm [3].
up for dynamic legform
[3]
up for dynamic legform
Figure 5: Legform impactor with s
Figure 6: Detail dynamic legform certification impactor
3. LOWER LEGFORM FINITE ELEMENT
MODEL
3. 1- STATIC TEST
3.1.1- Bending Test
The static bending test was represented in the FE model,
Hypercrash interface as shown in figure 7. The sides of the
eISSN: 2319-1163 | pISSN: 2321-7308
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139
Legform impactor with skin and foam covering [3]
Detail dynamic legform certification impactor [3]
LOWER LEGFORM FINITE ELEMENT
The static bending test was represented in the FE model,
Hypercrash interface as shown in figure 7. The sides of the

__________________________________________________________________________________________
tibia was fully constrained, defining clamps holding the tibia.
Shell elements were used to model all parts in the static
bending test with steel properties assigned. A 16mm diameter
cylindrical knee joint was modelled with the length of 20mm,
a thickness of 3mm, density of 1100kg/m3 and Young's
modulus of 650MPa. Concentrated force was applied at 2m
from the center of the knee joint, the normal horizontal force
applied is tabulated in table 1. Type 7 - multi usage contact
interface was assigned on the model, as the nodes were well
connected, self-impact was applied.
Figure 7: FE model of static bending test set-up
Table 1: Concentrated force(N) applied on static bending test
t f(t)
1 15
2 30
3 55
4 73
5 85
6 97
7 115
8 130
9 143
10 155
11 165
12 175
13 185
14 195
15 200
16 205
17 210
18 215
19 220
The static shearing test is similar to the bending test, therefore
the FE model was modified to achieve the static shearing test
set up. An additional 2mm flat bar was added to restraint the
femur movement. In addition, the concentration force was
applied 50mm from the center of the knee joint. All material
and properties used are the same as the static bending test.
Figure 8 and table 2 shows the static shearing test set up and
the normal horizontal force applied.
Figure 8: FE model static shearing test set up
Table 2: Concentrated force(N) applied on static shearing test
t f(t)
0 0
1 300
2 700
3 1400
4 2250
5 2900
6 3500
7 3700
8 3900
9 4100
3. 2- DYNAMIC TEST
The dynamic certification involves a more complex set up,
with an additional covering of 25mm flesh and 6mm skin. The
tibia, femur and knee joints were modeled using shell
elements using the exact properties used in the static test,
while the flesh and skin were modeled using solid elements.
Both femur and tibia were assigned as rigid bodies with the
material properties of steel. A mass of 6.87kg and 2.65kg was
added respectively on the femur and tibia rigid bodies,
satisfying the weight requirement of 8.6kg for femur and
4.8kg for tibia, forming a legform impactor of total 13.4kg.
The center of gravity of the femur and tibia was tuned in the
software to 711mm and 261mm from the end of legform. The
moment of inertia of femur about the horizontal axis through
it's center of gravity and perpendicular to the direction of
impact is 0.128kgm2 while the moment of inertia of tibia is
0.126kgm2.
As specified in EEVC/WG17, CF45-Confor foam was used in
representing the flesh of the human leg. The solid element was
interpreted as material type 70 in Hypercrash, foam with

__________________________________________________________________________________________
tabulated law. The density assigned to the material was
96.11kg/m3 with an inital young modulus of 100MPa and a
poison ratio of 0.28 as reference to Alireza Noorpoor and
Kiasat (2008)[4] . The stress and strain curved assigned to the
foam was tabulated in figure 9, the value was modified based
on Shahbeyk and Abvabi (2009) [5].
Neoprene was used to represent the skin in the simulation, the
arthur had modeled solid elements with visco-elastic material-
type 34 in Hypercrash. The initial density assigned was
1100kg/m3 with bulk modulus of 102MPa. The short and long
time shear modulus was indicated as 8.45MPa and 3.90MPa
respectively refering to Shahbeyk and Abvabi (2009) [5].
Figure 10 shows the FE model of the legform used in the
dynamic certification test. The mesh density increases near the
knee joint area to achieve more accurate results. Due to run
time constaint, fine meshes throughout the legform was
avoided.
Upon completion of the legform modeling, an aluminium
impactor of 9.366 kg was impacted horizontally at a velocity
of 7.5m/s into the stationary legform as shown in figure 11.
Two contact interfaces were applied on the dynamic legform,
both using type 7 - multi usage. The first contact applied was
self impact on the legform and the second with the impactor as
the master and the skin as the slave.
An accelerometer was assigned under the data history panel,
this enables the author to extract the upper tibia acceleration in
Hyperview.
Figure 9: Stress strain curve for Confor foam CF45
Figure 10: FE dynamic legform model
Figure 11: Dynamic certification test set up
4. VALIDATION OF LOWER LEGFORM
IMPACTOR
4. 1- STATIC CERTIFICATION TEST RESULTS
4.1.1- Bending Test
As specified in the EEVC/WG17 report, the legform has to be
certified statically and dynamically. Figure 12 shows the
simulation of static bending test set up in the Hypercrash, pre-
processor interface. An increasing concentrated force was
applied 2m from the centre of the knee joint and the resulting
bending angle was recorded. A graph of the applied force vs
the bending angle was plotted affirming the results were
within limits. The energy taken to generate a 15° bending
angle is 106.37J which is within the acceptable range of
100±7J. Figure 13 shows the bending angle vs force diagram
of the simulated results and the EEVC/WG17 limitations.
Figure 12: FE Static Bending certification test
Figure 13: Bending Angle Vs Force graph

__________________________________________________________________________________________
Figure 15 shows the simulation of the static shearing test. For
the shearing set-up, the tibia was also fully constrainted at the
sides with an increasing force applied 50mm from the center
of the knee joint. In this test, the shearing displacement was
observed. A graph of applied force vs shearing displacement
was plotted agaist the EEVC/WG17 limits. The results of the
simulation are shown in figure 16 and were proven to be
within limitations.
Figure 14: FE Static Shearing certification test
Figure 15: Shearing displacement Vs Force
4. 2- DYNAMIC CERTIFICATION TEST
RESULTS
A dynamic simulation was performed with a complete legform
with flesh and skin and an aluminium impactor. The impactor
has an initial velocity of 7.5m/s and the impacted point is
50mm from the center of the knee. The maximum bending
angle, maximum shearing displacement and the upper tibia
acceleration was observed. Table I shows the results achieved
in the dynamic certification and the EEVC limits. It can be
observed that the maximum bending angle and the upper tibia
acceleration falls within the limitation. Although the shearing
displacement did not achieve the minimum shearing
displacement of 3.5mm, it is still within the 20 percent FEA
error tolerance.
Table 3: Dynamic certification test result
Criteria Analysis Results EEVC/WG17
limitations
Maximum Bending
Angle (º)
8.12 6.2-8.2
Maximum Shearing
Displacement (mm)
2.83 3.5-6.0
Upper Tibia
Acceleration (g)
213.86 120-250
CONCLUSIONS
As lower extremity injuries are most common in vehicle-
pedestrian collisions, legform testing tool vastly contributes to
gauging the injury criterion on the leg during a vehicle-
pedestrian collision. These testing tools are widely used by car
manufacturers in designing pedestrian friendly vehicles. Since
the advancement of computerization, finite element analysis
has been a popular tool in simulating complex geometry and
real life situations due to its accuracy and its cost efficiency.
Being said so, finite element analysis and experimental test
comes along side, the FE model needs to be validated with
experimental results to ensure the modeling and input
parameters are accurate.
In this study, a FE legform model was model according
EEVC/WG17 specification. In this model, a knee of 16mm
diameter and 20mm of length was modeled as the deformable
knee element and the properties was tuned according to the
static and dynamic criterion. Upon fulfilling all static and
dynamic conditions, the legform is ready to be use for vehicle
bumper structure design and optimization.
REFERENCES
[1] World Health Organization, 2013. Pedestrian safety - A
road safety manual for decision-makers and
practitioners.
[2] Yoshiyuki Mizuno, 2005. Summary of IHRA
Pedestrian Safety WG Activities - Proposed Test
Methods to Evaluate Pedestrian Protection Afforded by
Passenger Cars.
[3] European Enhanced Vehicle Comittee, 2002. EEVC
Working Group 17 Report Improved Test Methods to
Evaluate Pedestrian Protection Afforded By Passenger
Cars.
[4] Alireza Noorpoor, Akbar Abvabi and Mehdi Saeed
Kiasat, 2008. Development a New Model of
EEVC/WG17 Lower Legform for Pedestrian Safety.
World Academy of Science, Engineering and
Technology 41:191-198.

__________________________________________________________________________________________
[5] Sharif Shahbeyk and Akbar Abvabi, 2009. A Numerical
Study on the Effect of Accident Configuration on
Pedestrian Lower Extremity Injuries. Scientia Iranica.
[6] World Health Organization, 2013. Global Status Report
on Road Safety- Section3: Transport policies neglect
pedestrians and cylists.
[7] Kei Nagasaka, Koji Mizuno, Eiichi Tanaka, Sota
Yamamoto, Masami Iwamoto, Kazuo Miki and Janusz
Kajzer. Finite Element Analysis of Knee Injury Risks in
Car-to-Pedestrian Impacts. Traffic Injury Prevention,
4:345-354, 2003.
[8] Fuhao Mo, Catherine Masson, Dominique Cesari and
Pierre Jean Arnoux. Coupling Lateral Bending and
Shearing Mechanisms to Define Knee Injury Criteria
for Pedestrian Safety. Traffic Injury Prevention,
14,378-386, 2013.
BIOGRAPHIES
F. Tarlochan was born in Malaysia. He
obtained his Bachelors in Mechanical
Engineering and Masters in Biomedical
Engineering from Purdue University, USA.
His PhD was from Universiti Putra Malaysia.
He is currently an Associate Professor at
UNITEN and heads the Center for Innovation and Design.
Email: faristarlochan@gmail.com
Khoo Y.C was born in Malaysia. She
obtained her Bachelors in Mechanical
Engineering from Universiti Tenaga Nasiona
(UNITEN), Malaysia. She is currently
pursuing her masters at UNITEN in the field
of Mechanical Engineering.

Development and validation of eevc wg17 lower

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