Material Characterization for FEA of the Clinching Process of Short Fiber Reinforced Thermoplastics with an Aluminum Sheet

Abstract

Multi-material and hybrid constructions are increasingly used in the automotive industry with the aim of achieving significant weight reductions of conventional car bodies, and thereby lead to effective reductions of fuel consumption. In this respect, the use of aluminum and short fiber reinforced plastics represents an interesting material combination. A full exploitation of such a material combination requires a suitable joining technique. Among different joining techniques, clinching represents one of the most appealing alternatives for automotive applications. This contribution deals with the experimental tests for determination of material behaviour of two representative materials PA6GF30 and EN AW 5754, which are used for parameterization of material models needed for numerical analysis of the clinching process using the FE software LS-DYNA. With regard to the material modeling of the aluminum sheet, an isotropic material model based on the von Mises plasticity implemented in LS-DYNA was chosen. For the description of the strain hardening behaviour of the aluminum sheet at high equivalent plastic strains, the hydraulic bulge test was carried out in addition to the uniaxial tensile test. For modeling of the short fiber reinforced thermoplastic a semi-analytical model for polymers (SAMP-1) available in LS-DYNA was taken. This material model uses an isotropic pressure dependent yield surface for the description of homogeneous materials. Finally, the FE model of clinching process is presented and an outlook of planned activities is given in terms on determination of the yield surface and hardening behaviour of PA6GF30 at high plastic strains.