A New Approach for IIHS shell elements barrier model development

Copyright © 2009 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

A New Approach for IIHS shell elements barrier model

development

Salim Abdennadher (Altair)

Petros Goutas (CELLBOND), Franck Njilie (Altair)


IIHS side MDB : Radioss shell model

IIHS Side MDB aims to evaluate vehicle occupant protection

Barrier shape and crushing strength represents SUV’s and pickups vehicle front ends.


Honeycomb scaled cell size modeling method

Honeyomb structure

3

5

056.16

S

tm

Mean crushing strength in principal cell axe direction (T. Wierzbicki 1983)

S

t

S

t

=> Target time step and barrier number of elements adjusted by thickness to cell size ratio


Honeycomb scaled cell size modeling method

=> Applied successfully for ODB and FMVSS214/301 MDB

S

t

Realistic barrier deformation shape

Better prediction of loading events in full vehicle crash test simulation.

Better prediction of biomechanical criterion

CPU time acceptable regarding the accuracy improvement


Safety tools : development scheme

M


Parameters IIHS Side FE Model Version 100

Radioss Version 10

Natural time step (µs) 1.0

Nodes 474,926

1D elements (beam /

spring) 2/28

Shell 4-nodes 492,959

Shell 3-nodes 1,619

Solids (Tetra4 / Bricks) 0/17,731

IIHS side MDB : Radioss model statistics


Test configuration IIHS with or without

bumper

Mass of trolley and

impactor (kg)

Impact velocity

(m/s)

Number of

tests

IIHS against flat LCW w

1503 13.9 m/s 2

IIHS against flat LCW w/o 1503 11.5 m/s 2

Pole against IIHS w 1498 8.3 m/s 2

Sill against IIHS w/o 1499 7.9 m/s 1

Sill against IIHS w 1499 7.9 m/s 1

IIHS side MDB : Validation test matrix


IIHS side MDB : Beta version validation status

Entrapped air has some effect at certain level of crush.


IIHS side MDB: Cellbond sample test

Sample shape after full crash

Impactor (falling mass)

Rigid support & loadcell

Honeycomb

sample

Test set up


IIHS side MDB: Cellbond sample test correlation


IIHS side MDB: Flat wall test

Entrapped air has significant effect at certain level

of crush.

The air effect will be introduced by using Radioss

monitored volume with adequate pressure function.

Modeling air effect


IIHS side MDB : release version validation status


IIHS side MDB : release version full vehicle crash test


Conclusion & perspective

Conclusion

In some test configuration (mainly rigid flat wall cases), air entrapped inside honeycomb cells

generates additional resistance to honeycomb structure.

The air effect modeling option has been validated through sample tests provided by CELLBOND.

In order to enhance the IIHS MDB Radioss FE model reliability, air effect has been successfully modeled.

The actual model accuracy has been proven for the hole validation test matrix (pole impact, Sill test …)

Perspective

Carry back the air effect modeling option to ODB and FMVSS214/301

Partnership with CELLBOND : European side MDB coming soon.

Technology

A New Approach for IIHS shell elements barrier model development