A CONSTITUTIVE THERMO MECHANICAL MODEL FOR SOLIDIFICATION PROBLEMS OF METALS

D. CELENTANO; S. OLLER; E. OÑATE

Jornada; Journées Numériques de Besançon; 1991

In this paper, the solidification process of metal pieces, modeled with the finite element method, is described. For this purpose, a model based on the rigorous thermodynamical principles has been developed. As a first approach to the problem, the following hypothesis has been adopted: - Weak coupling of physical a phenomenon, which implies that, the thermal and mechanical problem are solved separately, but considering the reciprocal influence between them. - The Thermal problem is studied using a temperature-based weak Galerkin formulation (which includes the moving boundary condition) in the framework of so called fixed domain methods. The thermal properties can depend on the temperature and the latent heat is released in an isothermal way or in a range of temperatures, depending of the material considered. All that phenomena, contribute to make the problem highly nonlinear.   - The mechanical problem is approached in the general isotropic plasticity theory frame. The mechanical properties of the materials are temperature-dependent. Using the ?Total. Lagrangian Formulation?, a large deformation constitutive law is formulated to describe the different behaviors of the materials and the different states of the solidifying metal (liquid, mushy and solid), - The convection effect k the liquid, as well as the heat generated by plastic deformation, is neglected, - A contact model is considered. Furthermore, a simple solidification problem is analyzed. The numerical results are compared with those obtained by another author.