Material anisotropy and plasticity formulations

We investigate in detail how initially structural anisotropy and deformation-induced anisotropy and deformation-induced anisotropy are considered in Green-Naghdi formulation of elastoplasticity. An oriented elastic-plastic medium model is obtained by permitting the microscopic bond substructure to rotate rigidly relative to the matrix. This model is reduced to Loret's substructure-based elastic-plastic model when a special stress-free configuration is taken