Viscoplastic behaviour of porous metallic materials saturated with liquid .1. Constitutive equations

Close to their melting point, metallic alloys containing a liquid phase can be described, in the high solid fraction range, as viscoplastic porous media saturated with liquid. In this article, a model is proposed in the general framework of the mixture theory. A constitutive equation for the deformation of the rate-dependent porous solid phase is given which is intended to improve the classical rheological description of metallic solid-liquid mixtures, in particular, in the case of non-negligible interstitial liquid pressure. Three deformation paths are studied in the frame of this constitutive equation: shear deformation, drained hydrostatic deformation and constant volume deformation in undrained conditions. The characteristic functions appearing in the constitutive equation will be identified, using these three deformation paths in the experimental part of this study. (C) 1997 Elsevier Science Ltd.