Development and Optimization of Instrument Panels for Frontal Crash with LowerBodySled

Torsten Gärtner – TECOSIM Technische Simulation GmbHOliver Ganßloser – Trenkwalder Engineering GmbH

2nd EUROPEAN HYPERWORKS TECHNOLOGY CONFERENCE 2008

30.09.-01.10.2008, Strasbourg, France

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

2

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison Sled Test – Lower Body Sled

Simulation Model and Results

Development Process

Conclusions

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

3

Problem Definition

development of instrument panels with respect to knee impact currently done with

sled tests or

vehicle crashes

in testing and simulation

using fully equipped models is

costly

time consuming

new approach should

simplify test setup

reduce number of components in system

still representing effects of knee impact

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

4

Basic Concept

test setup reduced to relevant components only

instrument panel – with knee airbag if used

dummy legs

foot area

vehicle crash / sled test with full restraint system

simplified test procedure with relevant components

LoBoS (Lower Body Sled)

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

5

Basic Concept – cont.

in LoBoS not used components are

cabin

steering wheel

seat

belt

driver / passenger airbag

dummy torso

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

6

Test Bench: Setup

tow sled with hitch

acceleration sled

sled brake

leg impactor

instrument panel

support

base framebungee cable

electric drive

foot area

analogous pelvis mass

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

7

Test Bench: Functionality

tow sled moves

forward and hitch locked

tow sled pulls acceleration sled

backwards into required strain position

release mechanism unlocks the

acceleration sled

deceleration of the acceleration sled directly before knee contact

intrusion of legs due to kinetic energy into instrument panel

respectively released airbag

1 2 3

4 5acceleration sled moves forward and triggers DAQ and

high speed camera

6

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

8

Test Bench: Functionality

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

9

Energy Calculation

energy-conformal simulation of crash scenario necessary

IP

IP-stiffness

pelvis

LowerBodySled

m2

v2

a(t)

IP

IP-stiffness

pelvis

Sled Test

m1

v1=0

m2

v2

2

222

1vmEkin

physical method

same work on pelvis between knee contact to IP (tc) and maximum pelvis forward movement (tΔv=0)

determining parameters

analogous pelvis mass (m2)

impact velocity (v2)

pelvis mass in LoBoS calculated from work on pelvis and impact velocity

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

10

PelvisFemur Belt

Abdomen

Seat

Energy Calculation – cont.

work on pelvis calculated from test or simulation data

forces from abdomen and seat neglected due to minor influence in longitudinal direction

Beckenarbeit

-2000

-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 0,05 0,1 0,15 0,2 0,25

Weg (m)

Kra

ft (

N)

Fo

rce (

N)

Pelvis forward movement (mm)

mpelvis,eff*apelvis, global_x

tc tΔv=0

Total Work Pelvis

total work on pelvis calculated as W = mpelvis, eff * apelvis, global_x

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

11

Energy Calculation – cont.

total work on pelvis reduced by work from belt systemGurtarbeit

-2000

-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 0,05 0,1 0,15 0,2 0,25

Weg (m)

Kra

ft (

N)

Work Belt

Fo

rce (

N) Fbelt, global_x

tΔv=0

tc

Pelvis forward movement (mm)

Time (s)

v rel. Becken

-2

-1

0

1

2

3

4

5

0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16

Zeit (s)

Gesch

win

dig

keit

(m

/s)

Relative Pelvis Velocity

Velo

cit

y (

m/

s)

tc

tΔv=0

vpelvis,rel,max

impact velocity is maximum relative pelvis velocity between knee contact to IP (tc) and maximum pelvis forward movement (tΔv=0)

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

12

Comparison Sled Test - LowerBodySled

Loadcase FMVSS208 – 50%ile, 40kph, unbelted

Femur_right

Femur_left

-8

-7

-6

-5

-4

-3

-2

-1

0

1

0 0,05 0,1 0,15 0,2 0,25 0,3t [s]F

[k

N]

Schlittenversuch

Knieschutztestanlage

-8

-7

-6

-5

-4

-3

-2

-1

0

1

0 0,05 0,1 0,15 0,2 0,25 0,3t [s]

F [

kN

]

Schlittenversuch

Knieschutztestanlage

Sled test

LowerBodySled

Sled test

LowerBodySled

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

13

Comparison Sled Test - LowerBodySled

Loadcase EuroNCAP– 50%ile, 64kph, belted

Femur_right

Femur_left

-5

-4

-3

-2

-1

0

1

0 0,05 0,1 0,15 0,2 0,25 0,3t [s]

F [

kN

]

Schlittenversuch

Knieschutztestanlage

-5

-4

-3

-2

-1

0

1

0 0,05 0,1 0,15 0,2 0,25 0,3t [s]

F [

kN

]

Schlittenversuch

Knieschutztestanlage

Sled test

LowerBodySled

Sled test

LowerBodySled

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

14

Simulation Model: Dummy Legs

impactor consists of legs cut from RADIOSS HIII-xx%ile rigid Dummy

pelvis is rigid body with analogous pelvis mass (m2)

pelvis H-Point has guidance in longitudinal direction

rotation about transverse axis free

m2

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

15

Simulation Model: Instrument Panel

IP consists of all necessary parts

CCB

IP Carrier

Steering System

Glovebox

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

16

Simulation Model: Complete Model

pelvis positioned on H-Point

legs positioned in foot area

Initial conditions as calculated

pelvis mass m2

impact velocity v2

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

17

Simulation Model: Results

Example FMVSS208 – 50%ile, 40kph, unbelted

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

18

Simulation Model: Results – cont.

Example FMVSS208 – 50%ile, 40kph, unbelted

Left femur force very high due to stiff glovebox and blocking with CCB

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

19

Development Process

Process starts with Energy Calculation

based on data of vehicle crash, sled test or occupant simulation

if data not available default values based on experience can be used

Setup Simulation model

including all necessary parts

material models based on tensile and/or bending tests

Initial validation of simulation model against LoBoS test

Optimization of instrument panel in simulation

Verifying simulation results with test

LoBoS

Contents

Problem Definition

Basic Concept

Test Bench

Energy Calculation

Comparison

Simulation Model

Development Process

Conclusions

Perspectives

20

Conclusions

LoBoS approach is a simplified test procedure for knee impact

using LoBoS can significantly reduce number of complex and costly sled tests resp. vehicle crashes

results show good correlation with sled tests resp. vehicle crashes

shortening development process of knee protection systems due to autarkic development and testing of these systems

Contact:

TECOSIM Technische Simulation GmbHDipl. Ing. Torsten GärtnerDept. Manager SafetyFerdinand-Stuttmann-Straße 15D-65428 RüsselsheimTel.: +49 (0) 6142 / 8272 370Fax: +49 (0) 6142 / 8272 249Mail: t.gaertner@de.tecosim.com

Trenkwalder Engineering GmbHDipl. Ing. Oliver GanßloserHead of Engineering ServicesMarie-Curie-Straße 19D-75359 Schwäbisch GmündTel.: +49 (0) 7171/ 60511-25Fax: +49 (0) 7171/ 60511-20Mail: o.ganssloser@trenkwalder.com