Effects of sphere size and fracture parameters on adhesive wear in elastic-plastic spherical microcontacts

The present study examines how sphere size and fracture parameters influence adhesive wear between an elastic-plastic gold sphere and a rigid flat. The sphere is subjected to combined normal loading and tangential displacement. To this end, the finite element (FE) method is employed. The adhesive pressure, derived from the Lennard-Jones (LJ) potential, is implemented on both the spherical and rigid flat surfaces via a user subroutine. The full stick contact condition is employed between the sphere and the rigid flat. The Johnson-Cook (JC) failure and fracture energy criteria are employed to capture damage initiation and evolution, respectively, during the tangential displacement. The simulation results reveal that the influence of adhesion on dimensionless wear volume and wear rate diminishes as the sphere radius increases from 0.5μm to 5μm, particularly when the dimensionless normal load is smaller than 2.5. Additionally, the dimensionless wear volume and wear rate reach their peaks at dimensionless fracture energies of 1.0 and 1.4, respectively. A fracture strain of 0.5 results in the maximum values for both dimensionless wear volume and wear rate. Finally, the influence of dimensionless fracture energy and fracture strain on fracture propagation mode is explored.