Simulation of Orientation in Injection Molding of a Highly Concentrated, Short Glass Fiber Thermoplastic Composites

This paper presents a 2D coupled Hele-Shaw flow approximation for predicting the flow-induced orientation of injection molded composite parts within a commercial concentration range. For a highly concentrated short glass fiber PBT suspension, the impact of inter-particle interactions and the orientation at the gate is investigated for a center-gated disk using a time-delayed orientation evolution equation and their material parameters determined from rheometry. Experimental orientation at the gate and at several radial positions in the cavity is determined using the method of ellipses. The orientation evolution equations are discretized using discontinuous Galerkin Finite Elements. Model predictions are significantly improved by using a localized orientation measured experimentally at the gate region instead of random orientation assumed in previous studies. Model modifications, orientation at the gate, and coupled simulations are required to improve the prediction of the fiber orientation.