ROTATIONAL DISSIPATION DURING MICROSPHERE IMPACT

In this study the dissipative effects due to microsphere rotation in the presence of adhesion during contact were investigated by means of mathematical analysis and numerical simulation. Three sources of rotational moments were considered: a moment about the mass center of the tangential contact force, a moment associated with the material rolling deformation and another with the peeling of the adhesion bond. The latter two are couples proximate to the contact region. A numerical model based on the results of the mathematical analysis was used to simulate the two-dimensional normal and oblique impact of a microsphere. The results show that the magnitude of rolling deformation and adhesion bond peeling moments are proportional to a power of the contact radius. Consequently, because of the small radius of microspheres, the effect of rotational dissipation due to these moments can be neglected. For example, when predicting microsphere rebound during impact, only the moment of the tangential force needs to be considered when considering microsphere rotation.