INTEGRATED SIMULATIONS OF STRUCTURAL PERFORMANCE, MOLDING PROCESS, AND WARPAGE FOR GAS-ASSISTED INJECTION-MOLDED PARTS - I - ANALYSIS OF PART STRUCTURAL PERFORMANCE

Whether it is feasible to perform an integrated simulation for structu ral analysis, process simulation, as well as warpage calculation based on a unified CAE model for gas-assisted injection molding (GAIM) is a great concern. In the present study, numerical algorithms based on th e same finite element mesh used for process simulation were developed to simulate the bending performance of gas-assisted injection-molded p arts. Polystyrene and nylon plates designed with five different channe l geometries were gas-assisted injection-molded. Part flexible strengt h was measured via bending tests. It was found that part stiffness bas ically increases linearly with the inertia moment of the plate. Gas ch annel design results in part structural reinforcement by introducing a n additional moment of inertia determined by the shape and the dimensi on of the channel section as well as the hollowed-core geometry. An an alysis algorithm based on VRT/DKT elements superimposed over beam elem ents representing gas channels of various section geometries was devel oped to evaluate part bending behavior. An equivalent diameter was ass igned to the beam element so that both the original gas channel and th e circular beam have the same moment of inertia. The simulated results were also verified with ANSYS 3-D and 2 1/2-D analysis. The simulatio ns show reasonable accuracy as compared with measured results and pred ictions from ANSYS. This investigation indicates that it may be feasib le to achieve an integrated simulation for GAIM under one CAE model, r esulting in great computational efficiency for industrial application. (C) 1998 John Wiley & Sons, Inc.