Homogenization of fibre reinforced composite with gradient enhanced damage model

Classical finite element simulations face the problems of losing uniqueness and strain localization
when the strain softening of materials is involved. Thus, when using continuum damage model
or plasticity softening model, numerical convergence will not be obtained with the refinement of the finite element discretization when strain localization occurs.
Gradient-enhanced softening and non-local continua models have been proposed by several researchers in order to solve this problem. In such approaches, high-order spatial gradients of state variables are incorporated in the macroscopic constitutive equations. However, when dealing with complex heterogeneous materials, a direct simulation of the macroscopic structures is unreachable, motivating the development of non-local homogenization schemes.
In this work, a non-local homogenization procedure is proposed for fiber reinforced materials.
In this approach, the fiber is assumed to remain linear elastic while the matrix material is modeled as elasto-plastic coupled with a damage law described by a non-local constitutive model. Toward this end, the mean-field homogenization is based on the knowledge of the macroscopic deformation tensors, internal variables and their gradients, which are applied to a micro- structural representative volume element (RVE). Macro-stress is then obtained from a homogenization process.