Micromechanics of Rough Interfaces

The mechanical behavior of rough interfaces is modeled from a micromechanical viewpoint. A kinematically driven mechanistic approach is adopted which explicitly considers the interaction of asperities on the fracture surface. The mating asperities are assumed to behave in accordance with contact mechanics postulates of non-conforming bodies. The roughness of the fracture surface is represented via statistical distributions of asperity contact normal and asperity heights. A directional distribution function of asperity contact orientations is introduced recognizing that the asperity contacts are not equally likely in all directions. Both the elastic deformation and frictional sliding under oblique loading are modeled at asperity contacts. Thus, the resultant model naturally accounts for the coupling between normal and shear behavior of rough joints, even though at asperity contact level there is no such coupling. An iterative procedure is implemented to obtain the asperity contact forces at each load increment, recognizing that the asperity contact force distribution is not always known a priori. The derived model is utilized to understand the effect of surface roughness and asperity friction on the initial normal and shear stiffness behavior of rough interfaces. The calculated initial normal and shear stiffness are then used to investigate the plane wave propagation behavior through interfaces.