Property ModellingImpact testing and simulation of a polypropylene component. Correlation with strain rate sensitive constitutive models in ANSYS and LS-DYNA.

A 20% mineral filled polypropylene homopolymer (Hifax XM2 U16 from LyondellBasell Industries) was studied. Correlation between experimental impact tests of components and tensile tests on specimens with simulations in ANSYS and LS-DYNA were conducted. The main goal of these tests was to evaluate the validity of elasto-plastic strain rate sensitive constitutive models implemented in both codes. Initially, strain localisation or necking phenomena were studied by simulating quasi-static tensile tests in ANSYS. An iterative method was used to match experimental force-displacement curves and so obtain true stress-strain curves as input for finite element analysis programs. Subsequently, the experimental impact testing of parts manufactured from the mineral filled polypropylene was simulated in ANSYS and LS-DYNA.It was found that the viscoplastic strain rate sensitive Perzyna's model compared well with test results from force-time and velocity-time curves but did not adequately describe the high force levels developed, particularly at the start of the tests. Additional sensitivity analyses in terms of element type, contact stiffness and mesh density were also carried out. Yield stress rate dependency was evaluated using the material model MAT 24 in LS-DYNA and, in addition, yield stress and elastic modulus rate dependency was evaluated with MAT 19. Both models offered very similar results. An initial attempt to simulate failure was also carried out with MAT 24.