Numerical simulation of fiber orientation in injection molding of short‐fiber‐reinforced thermoplastics

The present study develops a numerical simulation program to predict the transient behavior of fiber orientations together with a mold filling simulation for short‐fiber‐reinforced thermoplastics in arbitrary three‐dimensional injection mold cavities. The Dinh‐Armstrong model including an additional stress due to the existence of fibers is incorporated into the Hele‐Shaw equation to result in a new pressure equation governing the filling process. The mold filling simulation is performed by solving the new pressure equation and energy equation via a finite element/finite difference method as well as evolution equations for the second‐order orientation tensor via the fourth‐order Runge‐Kutta method. The fiber orientation tensor is determined at every layer of each element across the thickness of molded parts with appropriate tensor transformations for arbitrary three‐dimensional cavity space.