Injection molding is widely used in producing various plastic parts due to its high productivity, and the demand for injection molded products with high precision is increasing. The accurate prediction of shrinkage and warpage of injection molded parts is important to achieve successful mold design and product precision. In this study, the analysis of shrinkage and warpage of injection molded parts was carried out in consideration of the residual stresses during the packing and cooling stages of injection molding. In residual stress analysis, a rheologically simple thermoviscoelastic material model was assumed to consider the stress relaxation effect and describe the mechanical behavior according to the temperature change. The model considered the extra material that is added to fill the space created by shrinkage during the packing stage. The temperature and pressure fields were obtained from the results of a coupled analysis of the filling and post-filling stages. The deformation of injection molded parts after ejection induced by the residual stress and temperature change was analyzed using a linear elastic model. A three-dimensional finite element method was employed for the present numerical deformation analysis. In order to verify the numerical results obtained from the developed program, the simulation results were compared with the available experimental data in the literature. Each of the results of residual stress and the shrinkage was verified. In the case of residual stress, it was found that the simulation results predicted larger tensile residual stresses at the surface of parts compared to the experimental data. However, the predicted shrinkage was found to be accurate and described the effects of processing conditions well. Thus it was concluded that the currently developed program can be useful in predicting the shrinkage and warpage for the design of injection molded parts. Finally, an analysis of the shrinkage and warpage was carried out for a part with a curved shape to examine the robustness of the developed program.
