Prediction of Failure Behaviors in Polymers Under Multiaxial Stress State

Polymers are used in an increasing number of automobile parts to improve occupant and pedestrian safety as well as reduce weight and cost. Under impact, these parts are designed to effectively absorb energy through large deformation and failure. Failure phenomena are very important to predict because structural strength is drastically changed or lost after failure occurs. In this study, puncture tests for polypropylene sheets were performed at various impact velocities and frictions, and failure locations and timings in the sheets were investigated. Puncture tests generate a multiple stress state in the sheets and this heavily influences the failure behavior of the sheet material. CAE crash simulations using LS- DYNA were conducted to successfully predict deformation and failure behavior under a multiaxial stress state.