Frictional contact and wear behavior of gradient nanostructures: A crystal plasticity finite element study

This study develops a crystal plasticity finite element framework to investigate friction and wear in gradient nanostructures. A size-dependent constitutive model with dislocation-density evolution is combined with an energy-dissipation-based wear law to capture the mechanical response under sliding contact. The grain-size gradient through the depth is explicitly incorporated, and a homogenization scheme is used to connect microstructural features to the macroscopic contact behavior. The coupling between wear, contact pressure, plastic strain, and dislocation density is then investigated. Subsequently, the effects of different grain-size distributions on the contact response, plastic deformation, dislocation density evolution, and wear behavior are systematically analyzed. The results show that appropriate grain-size grading enhances surface mechanical performance and reduces friction and wear, thereby providing mechanistic insight into the superior wear resistance of gradient nanostructures under sliding contact.