Numerical prediction of fiber orientation and mechanical performance for short/long glass and carbon fiber-reinforced composites

Fiber reinforced polymer (FRP) composites offer exciting new possibilities for the green automotive industry, owing to their excellent mechanical properties, advantageous weight reduction and economical fuel consumption. In practice, accurately predicting fiber orientation is a critical issue in causing anisotropy in the mechanical properties of the FRP parts. Recently, an objective fiber orientation model, iARD-RPR (Improved Anisotropic Rotary Diffusion model combined with a Retarding Principal Rate model) proved significant in the field of fiber suspension rheology. Using state-of-the-art injection molding simulations, we therefore used the iARD-RPR model to explore the fiber orientation changes for various fiber components in regard to fiber length (short and long fibers) and fiber type (glass and carbon fibers). Under an extreme condition of higher fiber concentration and longer fiber lengths, a thicker core region and a narrow shell are always found in a typical orientation pattern of injection molded FRT parts. More importantly, these predicted orientation distributions provided to micromechanical material modeling computation of mechanical properties aid in the discussion on the reinforcing ability of short/long fibers and glass/carbon fibers based on the numerical simulation results. Comparisons with experimental data are also presented herein.