1

Takahiro IssikiAtsuhiro Konosu

Japan Automobile Research InstituteMasaaki Tanahashi

Japan Automobile Manufacturers Association, Inc.

Development of an FE Biofidelic FlexiblePedestrian Legform Impactor Model

(FLEX-GT-prototype Model)

TEG-0312 April 2007

4th Flex-TEG MTBASt, Bergisch Gladbach

1. Background

2. Construction of FE Flex-GT-prototype Model

3. Evaluation of FE Flex-GT-prototype Model

4. Conclusions

ContentsContents

2

1. Background

2. Construction of FE Flex-GT-prototype Model

3. Evaluation of FE Flex-GT-prototype Model

4. Conclusions

ContentsContents

BackgroundBackground

• The flexible pedestrian legform impactor type GT prototype (Flex-GT-prototype (called as Flex-GTα in the previous report1), 2))) was developed in Spring 2006.

• In this version, 1) the range of motion of the knee region, 2) the light weight of the bone parts, as well as 3) the biofidelity under assembly level (Thigh-Knee-Leg connected level) are improved.

• However, a validation study on the biofidelity of this impactor was not completely conducted, so it still needs to be validated.

• Thus, to conduct further validation study on the biofidelity of this impactor, an FE Flex-GT-prototype computer simulation model was developed.

3

1. Background

2. Construction of FE Flex-GT-prototype Model

3. Evaluation of FE Flex-GT-prototype Model

4. Conclusions

ContentsContents

Thigh(Flexible)

Knee(Ligamentrestraintsystem)

Leg(Flexible)

Flex-GT-prototype

Body Flesh

Thigh(Flexible)

Knee(Ligamentrestraintsystem)

Leg(Flexible)

FE Model

Body Flesh

Overview of Flex-GT-prototype and FE modelOverview of Flex-GT-prototype and FE model

4

Long bone

Construction of Flex-GT-prototype and FE modelConstruction of Flex-GT-prototype and FE model

Buffer(Solid)

Bone core(Solid)

Core binder(Rigid)

FE Model

Exterior housing(Rigid)

Impactside

(Cross sectional image)

Exterior housing(Magnesium or Nylon or Aluminum )

Bone core(GFRP*)

Buffer(Rubber)

Core binder(Magnesium)

Flex-GT-prototype

Impactside

(Cross sectional image)

＊GFRP: Glass Fiber Reinforced Plastics

Construction of Flex-GT-prototype and FE modelConstruction of Flex-GT-prototype and FE model

Knee

kneesprings

LCL*(Cable)PCL*(Cable)

MCL*(Cable)ACL*(Cable)

Femoralcondyle

Tibialcondyle

(Cross sectional image)

Impactside

Flex-GT-prototype

* ACL: Anterior Cruciate Ligament* PCL: Posterior Cruciate Ligament* MCL: Medial Collateral Ligament* LCL: Lateral Collateral Ligament

LCL*(Bar)PCL*(Bar)

MCL*(Bar)ACL*(Bar)

Femoralcondyle(Rigid)

Tibialcondyle(Rigid)

Impactside

FE Model(Cross sectional image)

5

Construction of Flex-GT-prototype and FE modelConstruction of Flex-GT-prototype and FE model

Flesh

FE Model

Rubber30 Neoprene

Impactside

- Top view -

- Top view -Flex-GT-prototype

Rubber30 Neoprene

Impactside Neoprene

Rubber 30

Neoprene

Rubber 30

Strain

Str

ess

(MP

a)

0

2

4

6

8

10

12

0 0.2 0.4 0.6 0.8 1

Flesh material stiffness

Thigh・Leg

Bone core

Strain gage

Knee

Displacement meter

Ligament cableLeg-1 (Strain)

Leg-2 (Strain)

Leg-3 (Strain)

Leg-4 (Strain)

Thigh-3 (Strain)

Thigh-2 (Strain)

Thigh-1 (Strain)

LCL (Elongation)MCL (Elongation)

PCL (Elongation)ACL (Elongation)

Impactside

Instrumentation of Flex-GT-prototype Instrumentation of Flex-GT-prototype

Femoralcondyle

Tibialcondyle

FE Model Thigh・Leg

FE Model Knee

Bar element

Bar elements

Bone core

Femoralcondyle

Tibialcondyle

6

1. Background

2. Construction of FE Flex-GT-prototype Model

3. Evaluation of FE Flex-GT-prototype Model

4. Conclusions

ContentsContents

Model evaluationModel evaluation

Partial evaluation

Thigh 3-pointbending simulation

Leg 3-pointbending simulation

Knee 3-pointbending simulation

Assembly dynamicbendingsimulation

Collision simulationwithsimplifiedcar model

Assembly evaluation

7

Model evaluationModel evaluation

Partial evaluation

Thigh 3-pointbending simulation

Leg 3-pointbending simulation

Knee 3-pointbending simulation

Assembly dynamicbendingsimulation

Collision simulationwithsimplifiedcar model

Assembly evaluation

Ram(Mass: 69.8 kg, Surface shape: R = 50 mm)

neoprene (5mm x 2)rubber30 (5mm x 2)neoprene (5mm x 1)

Support End

Support LengthThigh: 400 mm, Leg: 410 mm

Initial impact Speed: 0.99 m/s

Ground

Impactside

Thigh and Leg 3-point bending simulationThigh and Leg 3-point bending simulation

Model setup

8

Thigh 3-point bending (Kinematics)

Thigh and Leg 3-point bending simulationThigh and Leg 3-point bending simulation

Leg 3-point bending (Kinematics)

0 ms

40 ms

60 ms

20 ms

0 ms

40 ms

60 ms

20 ms

0

50

100

150

200

250

300

350

400

450

500

0 10 20 30 40 50 60

Deflection (mm)

Mom

ent (

Nm

)

ExperimentSimulation

Thigh and Leg 3-point bending simulationThigh and Leg 3-point bending simulation

0

50

100

150

200

250

300

350

400

450

500

0 10 20 30 40 50 60

Deflection (mm)

Mom

ent (

Nm

)

ExperimentSimulation

Thigh 3-point bending(moment-deflection response)

Leg 3-point bending(moment-deflection response)

9

Model evaluationModel evaluation

Partial evaluation

Thigh 3-pointbending simulation

Leg 3-pointbending simulation

Knee 3-pointbending simulation

Assembly dynamicbendingsimulation

Collision simulationwithsimplifiedcar model

Assembly evaluation

Ram(Mass: 69.8 kg, Surface shape: R = 50 mm)

neoprene (5mm x 2)rubber30 (5mm x 2)neoprene (5mm x 1)

Support End

Support Length: 400 mm

Initial impact Speed: 1.40 m/s

MCL

LCL

ACL

PCL

Ground

Impactside

Knee 3-point bending simulationKnee 3-point bending simulation

Model setup

10

Knee 3-point bending simulationKnee 3-point bending simulation

0 ms 20 ms

40 ms 60 ms

Knee 3-point bending (Kinematics)

0

100

200

300

400

500

0 20 40 60 80 100

Time (ms)

Mom

ent (

Nm

)

(a) Moment

0

4

8

12

16

20

24

28

0 20 40 60 80 100

Time (ms)

Liga

men

t elo

ngat

ion

(mm

)

MCL

ACL

PCL

(b) Ligament elongation

Knee 3-point bending simulationKnee 3-point bending simulation

ExperimentSimulation

ExperimentSimulation

11

Model evaluationModel evaluation

Partial evaluation

Thigh 3-pointbending simulation

Leg 3-pointbending simulation

Knee 3-pointbending simulation

Assembly dynamicbendingsimulation

Collision simulationwithsimplifiedcar model

Assembly evaluation

Leg suspension angle15 deg.

Free fall

without Flesh

rubber (5mm x3)neoprene(5mm x2)

Put neoprene and rubber sheets (5 sheets in total) onto the impact face

Knee jointsurface level

Pin Joint

support rig

Assembly dynamic bending simulationAssembly dynamic bending simulation

Experiment setup

12

5°

Stopper (rigid)

neoprene & rubber30

Fixed

Initial angularvelocity6.44 rad/s

Impact side

Assembly dynamic bending simulationAssembly dynamic bending simulation

Revolutional Joint(One degree of freedom)

Model setup

-1000

100200

Mom

ent

(Nm

)

-1000

100200

Mom

ent

(Nm

)

-1000

100200

Mom

ent

(Nm

)

-5

0

5

10

15

Elo

ngat

ion

(mm

)

-1000

100200

Mom

ent

(Nm

)

0 10 20 30 40 50Time (ms)

-1000

100200

Mom

ent

(Nm

)

-1000

100200

Mom

ent

(Nm

)

-1000

100200

Mom

ent

(Nm

)

-5

0

5

10

15

Elo

ngat

ion

(mm

)

-5

0

5

10

15

Elo

ngat

ion

(mm

)

0

50

100

150

200

250

300

Thigh-3 Thigh-2 Thigh-1 Leg-1 Leg-2 Leg-3 Leg-4

Max

imum

mom

ent (N

m)

0

5

10

15

20

25

Knee-ACL Knee-PCL Knee-MCL

Max

imum

elo

ngat

ion

(mm

)

ExperimentSimulation

(a) Wave forms (b) Maximum values

Experiment, Thigh-3Simulation, Thigh-3

Experiment, Thigh-2Simulation, Thigh-2

Experiment, Thigh-1Simulation, Thigh-1

Experiment, ACLSimulation, ACL

Experiment, PCLSimulation, PCL

Experiment, MCLSimulation, MCL

Experiment, Leg-1Simulation, Leg-1

Experiment, Leg-2Simulation, Leg-2

Experiment, Leg-3Simulation, Leg-3

Experiment, Leg-4Simulation, Leg-4

Assembly dynamic bending simulationAssembly dynamic bending simulation

13

Model evaluationModel evaluation

Partial evaluation

Thigh 3-pointbending simulation

Leg 3-pointbending simulation

Knee 3-pointbending simulation

Assembly dynamicbendingsimulation

Collision simulationwithsimplifiedcar model

Assembly evaluation

Initial impactSpeed: 11.1 m/s

Simplified car model

BLE*

BP*

SP*

Impactside

Collision simulation with simplified car modelCollision simulation with simplified car model

Model setup

* BLE: Bonnet reading edge* BP: Bumper* SP: Spoiler

14

Experiment

0ms 10ms 20ms 30ms

0ms 10ms 20ms 30ms

Simulation

Collision simulation with simplified car modelCollision simulation with simplified car model

-1000

100200300400

Mom

ent

(Nm

)

-1000

100200300400

Mom

ent

(Nm

)

-1000

100200300400

Mom

ent

(Nm

)

-505

10152025

Elo

ngat

ion

(mm

)

-1000

100200300400

Mom

ent

(Nm

)

0 10 20 30 40 50Time (ms)

-1000

100200300400

Mom

ent

(Nm

)

-1000

100200300400

Mom

ent

(Nm

)

-1000

100200300400

Mom

ent

(Nm

)

-505

10152025

Elo

ngat

ion

(mm

)

-505

10152025

Elo

ngat

ion

(mm

)

0

5

10

15

20

25

Knee-ACL Knee-PCL Knee-MCL

Max

imum

elo

ngat

ion

(mm

)

0

50

100

150

200

250

300

350

400

450

500

Thigh-3 Thigh-2 Thigh-1 Leg-1 Leg-2 Leg-3 Leg-4

Max

imum

mom

ent (N

m)

ExperimentSimulation

(a) Wave forms (b) Maximum values

Experiment, Thigh-3Simulation, Thigh-3

Experiment, Thigh-2Simulation, Thigh-2

Experiment, Thigh-1Simulation, Thigh-1

Experiment, ACLSimulation, ACL

Experiment, PCLSimulation, PCL

Experiment, MCLSimulation, MCL

Experiment, Leg-1Simulation, Leg-1

Experiment, Leg-2Simulation, Leg-2

Experiment, Leg-3Simulation, Leg-3

Experiment, Leg-4Simulation, Leg-4

Collision simulation with simplified car modelCollision simulation with simplified car model

15

1. Background

2. Construction of FE Flex-GT-prototype Model

3. Evaluation of FE Flex-GT-prototype Model

4. Conclusions

ContentsContents

ØIn this study, a computer simulation model of FE Flex-GT-prototype was developed, and its fidelity to an actual Flex-GT-prototype was evaluated.

ØBased on the evaluation study results, under the segmental level (thigh, leg, and knee parts) and assembly level loading conditions, it was verified the equivalence of the FE Flex-GT-prototype model to an actual one.

ØIn our further study, this model is utilized in evaluation of its biofidelity to finalize the Flex-GT specifications.

ConclusionsConclusions

16

References1) UN/ECE/WP29/GRSP/INF-GR-PS/Flex-TEG: Information on the Flexible

Pedestrian Legform Impactor GT Alpha (Flex-GT-alpha), TEG-021 (2006)2) UN/ECE/WP29/GRSP/INF-GR-PS/Flex-TEG: Evaluation Activities on Injury

Assessment Ability of the Flexible Pedestrian Legform Impactor GT Alpha (Flex-GT-alpha), TEG-022 (2006)

Thank you for your attentions!