FRONT TRACKING THERMOMECHANICAL MODEL FOR HYPOELASTIC VISCOPLASTIC BEHAVIOR IN A SOLIDIFYING BODY

In assessing the quality of castings, a major consideration is the formation of cracks due to the induced thermal stress field. A means for understanding the casting process is the development and numerical implementation of mathematical models which account for all the heat transfer and deformation phenomena occurring in a solidifying body. In this paper a front tracking finite element method is used for the calculation of temperature and stress field development in a solidifying pure metal. The solid/liquid interface position and its velocity are considered as primary variables of the heat transfer analysis. A rate form of the virtual work principle and a rate dependent viscoplastic-hypoelastic constitutive model are employed to solve the equilibrium equations and to account for the hydrostatic stress state on the freezing interface and the fact that the material is in a state of residual stress immediately after solidification. Examples of the applicability of the technique are given with the analysis of the solidification of pure aluminium under realistic cooling rates and material representation. The effects of melt pressure, cooling conditions and geometry of a continuously cast metal strand on the residual stress pattern are examined and reported. © 1990.