A numerical approach for injection molding of short-fiber-reinforced plastics using a particle method

This study proposes a numerical approach for predicting the injection molding process of short-fiber-reinforced plastics using the moving particle semi-implicit (MPS) method, which is a particle-simulation method. Unlike conventional methods using orientation tensors, this approach represents all fibers and resin as an assembly of particles, and automatically analyzes the interaction between fiber and resin and between fibers. In addition, this method can follow the motion of a specific fiber, which is a significant advantage over orientation tensors. This study simulated the injection molding of short-fiber-reinforced plastics; the thermoplastic resin was considered as an incompressible viscous fluid and the fibers were modeled as rigid bodies. The numerical result illustrated that the molding material was unidirectionally reinforced by short fibers since the fibers rotated and were aligned parallel to the flow direction due to the velocity gradient near the wall boundary. Moreover, the stagnation of resin at a corner was predicted. The results agreed well with previous studies, and the present approach was confirmed. Beyond this, we predicted the accumulation of fibers near the wall due to the velocity gradient, which could not be represented by conventional simulations based on orientation tensors.