3-D FEM analysis of the temperature field and the thermal stress for plastics thermalforming

The FEM software ARVIP-3D is developed to simulate the deformation, tempera ture field, thermal stress and warpage of 3-D plastics thermalforming and b low molding. Temperature has a great effect on plastics forming behavior by influencing the material performance parameters, the fluid viscosity and t he fluid behavior exponent. Combined with the rigid-visco-plastic FEM equat ion for forming computation, the Arrhenius and Williams equation for viscos ity computation, the Calerkin FEM equation for the temperature field, the F EM software is developed. Whilst simulating the 3-D temperature field, the dynamic heat-conduction boundary condition is adopted, latent heat and defo rmation heat being treated as dynamic internal heat source in FEM equation. The computational results of adopting the analytical method and the FEM pr ogram developed by the authors indicate that the program of analyzing the t emperature field is accurate. The simulation result of the temperature dist ribution corresponding to the thickness distribution agrees well with the e xperimental results of other researchers. This provides the theoretical bas is and a guide for acquiring the thickness distribution of a part by a simp le, convenient and non-destructive temperature measurement in practical pro duction, and provides a useful tool to optimize the technique to secure an even distribution of thickness in the part. The warpage and thermal-stress analysis can predict defects and optimize the cooling system to secure an e ven temperature distribution within the part to assure the part's final sha pe, practical performance and strength. (C) 2000 Elsevier Science S.A. All rights reserved.