A COUPLED THERMOMECHANICAL MODEL FOR THE SOLIDIFICATION OF CAST METALS

A coupled thermomechanical model to simulate solidification problems i n casting is presented. The model is formulated from a phenomenologica l point of view using a general isotropic thermoelasto-plasticity theo ry. Generalized phase-change effects accounting for the different ther momechanical behaviour of the solidifying material during its evolutio n from liquid to solid have been considered. For this purpose, a phase -change function, plastic evolution equations and a temperature-depend ent constitutive law have been defined. Full thermomechanical effects as well as variable thermal and mechanical boundary conditions are als o taken into account. Particular details concerning the numerical impl ementation of the model are given, where special emphasis is devoted t o the resulting highly non-linear fully coupled finite element equatio ns. The behaviour of this formulation is studied first in a simple que nching problem. Finally, a cylindrical casting test problem including phase-change phenomena, temperature-dependent constitutive properties and contact effects is analysed. Numerical results are compared with l aboratory measurements.