Multiscale modeling for analyzing slip weakening at material interfaces

Abstract

A multiscale framework is proposed for analyzing slip weakening at material interfaces. In the proposed model, discrete granular assemblies are attached to Gauss integration points to capture micro-structural characteristics of granular material, which furnishes the multiscale constitutive formulation. Interface shear slip is performed via penalty method and elasto-plastic decomposition, which formulates the frictional contact relationship. Furthermore, both linear and non-linear interface models are provided to examine slip weakening behavior. In the numerical implementation, both the resulting multiscale constitutive formulation and the frictional contact relationship, are implicitly embedded in conventional continuum-based finite element method (FEM) for solution. The multiscale framework is verified using an interface direct shear test, which shows good agreement between the analytical and numerical results. Cross-scale analyses are performed based on the proposed multiscale framework, which comprises mesh dependency, a macro-micro slip-weakening mechanism and staged responses. The interplay between interface slip weakening and material strain localization is successfully captured, by presenting the global and local responses during shearing where fabric anisotropy, coordination number, particle rotation, void ratio and deviatoric strain are considered.