On the Origin of Plastic Deformation and Surface Evolution in Nano-Fretting: A Discrete Dislocation Plasticity Analysis

Abstract

Discrete dislocation plasticity (DDP) calculations were carried out to investigate a single-crystal response when subjected to nano-fretting loading conditions in its interaction with a rigid sinusoidal asperity. The effects of the contact size and preceding indentation on the surface stress and profile evolution due to nano-fretting were extensively investigated, with the aim to unravel the deformation mechanisms governing the response of materials subjected to nano-motion. The mechanistic drivers for the material’s permanent deformations and surface modifications were shown to be the dislocations’ collective motion and piling up underneath the contact. The analysis of surface and subsurface stresses and the profile evolution during sliding provides useful insight into damage and failure mechanisms of crystalline materials subject to nano-fretting; this can lead to improved strategies for the optimisation of material properties for better surface resistance under micro- and nano-scale contacts.

Analysis of the Effectiveness of Removing Surface Defects by Brushing

“…With elements subjected to fatigue loads, surface defects may act as a notch contributing to stress concentration and, consequently, to early failure of the element. Damage and failure mechanisms of crystalline materials were analyzed in [ 1 ]. In addition, surface defects that are left on the component in production, or formed during product operation have a negative effect on the aesthetic and decorative qualities of the finished products [ 2 ].…”

Nonsingular Stress Distribution of Edge Dislocations near Zero-Traction Boundary

“…The broken symmetry near the dislocation-core and its movement due to external forces or thermal excitations play primary roles in the physical phenomena. For instance, the plastic deformation of a crystal is caused by a large flow of dislocations [ 4 , 5 ], and work hardening is caused by the dislocation arrangement formed in the crystal [ 6 ]. Otherwise, the nucleation and mobility of dislocations near the tip of a crack have a strong impact on the fracture mechanics of the material [ 7 ].…”