A Foam Material Model Validation Process for Crash Simulation Software

Energy absorbing foam padding is widely applied in various areas of modern cars in conjunction with increasing number of airbags as passive safety systems. High efficient energy absorbing foams which can be used to optimise energy absorption or minimise packaging space are particularly popular. Foam padding is applied in doors for pelvis and thorax protection, behind headliners for head impact protection, in knee bolsters and under steering columns for knee impact protection, in the foot well area for ankle- and tibia protection and in bumpers to meet competing pedestrian, pendulum and insurance requirements. Since passive safety systems are developed with the aid of modern virtual simulation software such as LS-DYNA, it is imperative to have accurate and reliable material models for the energy absorbing systems used for the said applications. This paper describes the material model validation of high efficient energy absorbing foam based on a test matrix of physical tests. High speed drop tower tests were used to define the basic material model parameters. Sled tests with a rigid impactor shape based on SID IIs, dummy pelvis and head impact tests with a Free Motion Head (FMH) form according to FMVSS201U were used to validate the models and assess their accuracy with respect to various complexity of foam sample geometry.