Modeling of Long Fiber Reinforced Plastics

Long fiber reinforced plastics (LFRP) have exhibited superior mechanical performance and outstanding design flexibility, bringing them with increasing popularity in the automotive structural design. Due to the injection molding process, the distribution of long fibers varies at different locations throughout the part, resulting in anisotropic and non-uniform mechanical properties of the final LFRP parts. Images from X-ray CT scan of the materials show that local volume fraction of the long fibers tends to be higher at core than at skin layer. Also fibers are bundled and tangled to form clusters. Most of the current micromechanical material models used for LFRP are extended from those for short fibers without adequate validation. The effect of the complexity of long fibers on the material properties is not appropriately considered. Thus, modeling of these materials is lagging behind the material manufacturing and design development, which in turn limits their further development. In this paper, a solution is found to take into the consideration of the complicated distribution of long fibers in LFRP parts based on Digimat software. The non-uniform distribution and bundling effect of the long fibers is considered by incorporating the fiber distribution information from X-ray CT scan images into Digimat-Abaqus coupled model. The effectiveness of the method is validated through physical testing data.