Mechanics

2003, The Second Special Issue

Y.N. Radayev

CONSTITUTIVE MODELS OF ANISOTROPIC DAMAGE AND MODELLING OF DAMAGING MICROPROCESSES IN SOLIDS

A thermodynamic analysis of three-dimensional anisotropic damage state and its time evolution is presented in an attempt to obtain a deeper insight into damaging phenomena and find the canonical state parameters required for a damage state description. The analysis of damage state is based on the canonical hidden variable technique and developed in the two canonical variants - the energy and the entropy ones. Thermodynamic damage state potentials in their canonical forms are obtained. In the case of isothermal damaging the canonical net stress tensor is derived. A variant of the canonical description of damage providing its notion originating from irreversible thermodynamics canonical definition of directional damage variable is discussed. The canonical representations of the thermodynamic damage state potentials in terms of damage tensors are derived. Those involve the only metric invariant of a damage state - the canonical norm. Directional damage averaging the damage represented by the second and the fourth rank damage tensors is considered. In order to demonstrate a superiority of the canonical formalism a general thermodynamic analysis of brittle and ductile damaging processes is carried out by the canonical technique. Universal equations of damage balance in the course of damage growth in solids are obtained.