Effect of Fiber Orientation on the Mechanical Properties of Long Glass Fiber Reinforced (LGFR) Composites

Long glass fiber reinforced (LGFR) composites have been widely used in automotive industry to reduce vehicle weight and maintain relatively high mechanical performances. Due to the injection molding process, the distribution of fiber orientations varies at different locations and through the panel thickness, resulting in anisotropic and non-uniform mechanical properties. The current practice of computer modeling of these materials is generally using isotropic properties adjusted by a certain scale factor. The effect of fiber orientation is not carefully considered due to the complexity of fiber orientation distribution in the LGFR parts.

The purpose of this paper is to identify key factors affecting vehicle attribute performances where LGFR composites are used; and provide an efficient way for accurate CAE modeling of LGFR composites. In this study, tensile coupons cut from a simple geometric injection molded plaque are tested. The tested material properties are compared to those from CAE predictions to understand how well the CAE predictions capture the material behavior with fiber orientation accounted for. The fiber orientation is obtained from injection molding simulations and mapped to the CAE model using Abaqus coupled with Digimat to perform micromechanical calculations on material properties. The stiffness of a more complex part at different locations is then compared between physical testing and CAE prediction. Finally the NVH performance of the whole panel is simulated using Abaqus to evaluate the fiber orientation effect.