Rheological characterisation and modelling of a glass mat reinforced thermoplastic for the simulation of compression moulding

Abstract

Abstract. The use of hybrid components in the automotive industry is steadily increasing due to their lightweight potential. By combining fibre-reinforced plastics with metallic materials, high-strength components with lower weight than monolithic metal parts can be realised. The overall aim of the project “HyFiVe” is to exploit this potential for electric vehicles by developing a scaled battery housing structure made of a glass mat reinforced thermoplastic (GMT) paired with unidirectional reinforced (UD) tapes and a metallic reinforcement frame. The GMT is formed by compression moulding and serves as the base of the battery housing structure. Numerical simulation is an efficient tool for process design that can determine a suitable process window and reduce experimental trial-and-error tests. Particularly, realistic modelling of the GMT flow behaviour is essential for reliable simulation results. In this contribution, the rheological properties of a GMT consisting of a polyamide 6 (PA6) matrix with 30% glass fibre reinforcement were determined. Isothermal compression tests were carried out with a parallel plate rheometer at different temperatures and varying squeeze rates. The squeeze force and punch displacement were evaluated to determine the rheological data of the GMT. Two methods for the modeling of the flow behaviour were considered. At first, pure shear flow was assumed and the viscosity was modelled as a function of the shear rate by means of a power-law. Secondly, a pure biaxial extension was assumed and the true stress was modelled in dependence of true strain and strain rate. Subsequently, for a verification of the material models, the compression tests were simulated in ABAQUS using the Coupled Eulerian-Lagrange (CEL) approach and the results were compared to the experiments.