Abstract: Considering the large meshing model and timeconsuming computation in large complicated multihole part injection molding simulation, in order to solve the problems, according to the principle of equivalent volume, a simplified method was used to substitute multihole featural section with a simple cross section of shape factor and equivalent thickness and to derivate the formula of shape factor and equivalent thickness. The formula was used to simulate a car rear door panel, which not only decreases the calculation time, but also accurately predicts the location of the weld lines and air traps. The method is useful for the complicated parts with similar features.

Key words: injection molding simulation, equivalent volume, equivalent thickness, shape factor, computer aided engineering (CAE)