Validation of Expanded Polypropylene (EPP) Foam Material Models for Low Speed Bumper and Pedestrian Protection Applications

Expanded Polypropylene (EPP) foams are most commonly used in automotive applications for pedestrian protection and to meet low speed bumper regulatory requirements. In today’s automotive world the design of vehicles is predominantly driven by Computer Aided Engineering (CAE). This makes it necessary to have a validated material model for EPP foams in order to simulate and predict performance under various loading conditions. Since most of the automotive OEMs depend on local material suppliers for their global vehicle applications it is necessary to understand the variation in mechanical properties of the EPP foams and its effect on performance predictions.

In this paper, EPP foams from three suppliers across global regions are characterized to study the inter-supplier variation in mechanical properties. In order to understand the effect of inter-supplier variation on vehicle performance, an LS-DYNA rate dependent material model is developed and validated for low speed and pedestrian protection (ped-pro) load cases.

The results show the variation in mechanical properties of EPP foams from different regions and their effect on ped-pro and low speed performance predictions.