A Continuum Damage Theory with Rotation Gradients

Deformation and damage evolution of materials often involve localization in some small regions, where the strain gradients and the interaction between defects are of significance. A phenomenological continuum damage theory with rotation gradient effects is presented in this paper based on the theory of couple stresses. The constitutive relations are formulated for centrosymmetrically isotropic materials and linear anisotropic materials. To illustrate the application of the present theory, the deformation and damage of a thin film/substrate system is investigated. It is found that the strain gradients exert a considerable influence on the damage distribution and failure behavior near an interface.