Thermoviscoelastic simulation of thermally and pressure-induced stresses in injection moulding for the prediction of shrinkage and warpage for fibre-reinforced thermoplastics

In this paper we present a detailed thermoviscoelastic formulation for the simulation of thermally and pressure induced residual stresses in injection moulded short-fibre-reinforced thermoplastics. The computed residual stres ses enable us to predict shrinkage and warpage in the finished products. We also apply an anisotropic version of a rotary diffusion equation to calcul ate the flow-induced fibre orientation distribution. The predicted fibre or ientation state, together with micromechanical theories, allows the incorpo ration of anisotropy in material properties into the thermoviscoelastic mod el. Finally we report three numerical examples to indicate the success of t he present model. (C) 1999 Elsevier Science B.V. All rights reserved.