Design and Analysis of a Microelectromechanical Device Capable of Testing Theoretical Models of Impact at the Microscale

This paper proposes a conceptual design for a microscale experimental device that could be used to investigate oblique, intermittent contact while allowing for tangential slip and adhesion/stiction at the contact interface. The discussion includes a formulation of a reduced-order model of the nonlinear device dynamics. Emphasis is given to a possible contact model that incorporates normal and tangential compliance, friction-like limits on the ratio of tangential to normal contact forces, adhesive interactions, and irreversible energy loss in the normal contact interactions. A preliminary theoretical and numerical analysis is performed on this contact model in order to assess the influence of adhesion and energy loss on the contact phase. The results consider both the case of a normal collision in the absence of coupling between normal and tangential degrees of freedom as well as the general case of an oblique impact with such coupling. The paper argues that there is great value in an experimental validation of such a model for microscale contact, as a growing number of devices either rely on contact directly or must accommodate and design for its possible occurrence. In addition, mention is made of a number of inconsistencies and paradoxes observed in macroscopic models of rigid-body contact with friction that warrant validation or resolution through appropriate experimental designs.