Boundary element analyses on the adhesive contact between an elastic sphere and a rigid half-space

Boundary element method is used to analyze the adhesive contact between an elastic sphere and a rigid half space. Lennard-Jones potential is used for the surface traction. In the past, the simulation for the adhesive contact between spheres usually used paraboloid approximation for sphere surface. In this paper, the adhesive contact is investigated using exact sphere. A new algorithm for boundary element method is proposed. The S-shaped load-approach curve and the whole solution can be obtained. The result is compared with the adhesive contact between a rigid paraboloid and an elastic half-space, and that between an elastic paraboloid and a rigid half-space. It is found that the Tabor parameter and the radius of sphere affect the adhesive contact. As the Tabor parameter is larger, the effect of the radius is larger. As the radius is smaller, the pull-off force and the pull-off distance for fixed-grips device are smaller. The adhesive contact for rigid paraboloid/elastic half-space can approximate that for elastic paraboloid/rigid half-space and that for elastic sphere/rigid half-space with small Tabor parameter and large radius. Finally, an approximate equation for the pull-off force vs. Tabor parameter is proposed.