Multiple Impact Simulations on Automotive Energy Absorbers Using a Recovery Based Material Model

For efficient prediction of single and multiple impacts on bumper energy-absorber systems, it is necessary to have certain important aspects represented by the model that represents the material of construction. These aspects include true stress-strain behavior, strain rate effects, hydrostatic effects, multiple failure criteria and recovery of material during unloading. An existing material model in the explicit solver LS-DYNA covers these aspects, and this paper aims at exploring the sensitivity of this model to finite element parameters. This is done by simulating multiple impacts on two designs, and comparing with test data. Results indicate that FE model parameters, stiffness variation, and contact definitions play a vital role in obtaining a solution.