Author: Jiang, Q., Liu, H., Xiao, Q., Chou, S.-F., Xiong, A.-H., & Nie, H.
Based on the effects of natural cooling on the warpage of the injection-molded parts, a concept of total warpage deformation was proposed. A three-dimensional numerical model of total warpage for the injection-molded parts of short-glass-fiber-reinforced polypropylene (PP) composites was established using coupled finite element method (FEM). The total warpage deformation is composed of two parts: stress-induced deformation during injection molding and thermally induced shrinkage deformation after ejection. The residual stress, temperature, and anisotropic thermal and mechanical properties formed in injection molding were subsequently transferred into the thermal stress analysis package as initial conditions. On account of the difference between the fluid and structural mesh, the tetrahedral and hexahedral mesh types were used in injection molding simulation and thermal stress analysis, respectively. The comparison between the simulation and experimental results showed that the simulated warpage deformation agreed well with the experimental measurements quantitatively and qualitatively, suggesting the validation of the proposed numerical model.