Composite layered materials: Anisotropic nonlocal damage models

Sophisticated constitutive equations have recently been proposed to describe the mechanical behavior and damage of heterogeneous materials. Using these equations, the finite element method makes it possible to predict the degradation of composite structures. However using standard finite element procedures, theses equations may lead to numerical problems (instabilities, damage localization, etc.) so that meaningful results are difficult to obtain. One of the solutions consists in writing the constitutive equations in a nonlocal framework. In this paper, extensions of the implicit gradient formulation, to anisotropic laminate structures, are proposed and validated in the case of a test structure.