A requirement for the safe design of thermoplastic parts is the ability to precisely predict mechanical behaviour by finite element simulations. The presented material model considers linear-elastic behaviour and non-linear orthotropic stress-state dependent viscoplastic deformation for arbitrary fibre distributions.
This work introduces a material modelling approach for explicit finite element simulations of injection moulded short fibre reinforced thermoplastics. The material model considers linear-elastic behaviour and non-linear orthotropic stress-state dependent viscoplastic deformation for arbitrary fibre distributions. Regarding elasticity and the initial yield surface, a micro-mechanical Mori-Tanaka based approach is applied. On the matrix level an isotropic quadratic yield surface is introduced which is transferred into a Tsai-Wu yield surface on the composite level. An analytical expression for non-linear hardening and a simplified consideration of strain rate dependency is presented. The constitutive equations were verified with the experiments of a self-compounded PPGF30 material regarding regarding tension, compression and shear at different orientation distributions.