Rotational dissipation during microsphere impact

In this study the dissipative effects due to microsphere rotation in the pr esence of adhesion during contact were investigated by means of mathematica l analysis and numerical simulation. Three sources of rotational moments we re considered: a moment about the mass center of the tangential contact for ce, a moment associated with the material rolling deformation and another w ith 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 mathem atical analysis was used to simulate the two-dimensional normal and oblique impact of a microsphere. The results show that the magnitude of rolling de formation and adhesion bond peeling moments are proportional to a power of the contact radius. Consequently, because of the small radius of microspher es, the effect of rotational dissipation due to these moments can be neglec ted. For example, when predicting microsphere rebound during impact, only t he moment of the tangential force needs to be considered when considering m icrosphere rotation. (C) 1999 Elsevier Science Ltd. All rights reserved.