Property ModellingIso-strain rate material behaviour curves applied to the finite element impact simulation

Tensile impact tests on polypropylene (PP) samples are simulated by a finite element method. A previously proposed characterisation method is applied to obtain the impact properties, and a simple elastic with rate-dependent plasticity material model is used to describe the material behaviour. Impacts at different energy levels are simulated, and a good force-time curve correlation is obtained between experimental and simulated results. The minimum sample rupture energy level is also predicted. However, non-negligible deviations are found between experimental and simulated displacement-time curves, the simulated plastic deformation being greater than the experimental one. This can be associated with the non-strain rate dependence of the elastic modulus and yield strength in the material model. A revision of the high-rate characterisation method and the use of alternative constitutive models that take into account this dependence should be the guidelines in order to achieve a better correlation between displacement-time curves of simulated and experimental tensile impact tests.