An incremental finite element procedure for cumulative damage of 2-D continua via two surface plasticity.

A numerical procedure is proposed, which is based on the finite element method and on a simple rate-independent constitutive model, in order to study the monoonic and cyclic mechanical behavior of two-dimensional solid continuous media under in-plane stess conditions. The material is assumed to experience a continuous damage process under load histories. The model adopts damage-dependent yielding and limit surface in stress space to predict the strength and deformation characteristics of the gross material under general loading paths. Reduction in size of the two surfaces as damage accumulates, and the adopted functional dependence of the material moduli on stress and damage, permit a realistic modeling of the material behavior. Satisfactory prediction is obtained of the generally nonlinear stress-strain response, degradation in stiffness during load cycles, and post-failure (strain softenening) behavior. Finite element implementation of the proposed model is feasible and computationally efficient. To test this, a sample application has been worked out concerning a holed plate of Aluminum.