Parameter sensitivity in microsphere impact and capture

In the presence of adhesion and under certain conditions a microsphere will be captured during a low speed impact with a substrate. The sensitivity of the capture velocity (the largest initial normal velocity at which capture occurs) to five physical factors is analyzed in this paper. The factors ar e the Hertzian stiffness, Dupre surface energy, the microsphere radius, a d amping coefficient associated with adhesion dissipation, and one associated with material dissipation. The sensitivity is determined by examining the effects of the factors on the capture velocity using a two-level, fractiona l factorial design layout. Capture velocities are determined using analytic al models. Results indicate that the Dupre surface energy and the microsphe re radius by far play the greatest role in the capture process. The Hertzia n stiffness and the dissipation coefficient associated with adhesion affect capture to a lesser extent; an interaction of the surface energy and the a dhesion energy dissipation can also play a small role.