FE-Modelling of the Rubber Mould Behaviour during Press Forming of Thermoplastic Composites

Rubber is a hyperelastic material with a non linear behaviour which is very different in tension and compression. The behaviour in tension shows an initially increasing stiffness, followed by a decreasing stiffness at higher strains, while in compression the stiffness is increasing at higher loads. In the present paper, the rubber mechanical properties in tension and compression are implemented in ABAQUS via a hyperelastic material model present in the FE package, which perfectly represent the tested material behaviour. The material model uses a strain energy potential polynomial of second degree to model the stress-strain curve of the material. The validation of the material model is shown and compared with the material tests. A sensitivity analysis for other properties such as the Poisson’s ratio and the friction coefficient between the two moulds is given. FE-simulations of the press forming process for the production of a U-beam are presented and compared with test results, showing good agreement.