Micromechanical analysis of friction anisotropy in rough elastic contacts

• Effect of anisotropic roughness on anisotropy of friction in rough elastic contacts.
• Scale transition by computational contact homogenization approach.
• 3D finite element analysis of sliding contact of rough surfaces in the finite deformation regime.
• Macroscopic slip rule is found to be non-associative in the tangential plane.
• Counterintuitive effects observed for compressible materials, particularly for auxetics.

Computational contact homogenization approach is applied to study friction anisotropy resulting from asperity interaction in elastic contacts. Contact of rough surfaces with anisotropic roughness is considered with asperity contact at the micro scale being governed by the isotropic Coulomb friction model. Application of a micro-to-macro scale transition scheme yields a macroscopic friction model with orientation- and pressure-dependent macroscopic friction coefficient. The macroscopic slip rule is found to exhibit a weak non-associativity in the tangential plane, although the slip rule at the microscale is associated in the tangential plane. Counterintuitive effects are observed for compressible materials, in particular, for auxetic materials.