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Switches, connectors and electrical contacts are ubiquitous elements in today's ''more electric society''. Despite various design directions which might be thought to reduce the number of make-break electromechanical contacts, contacts still provide the largest single source of failure in automotives, aircraft, machine tools, computers, and consumer electronics. While great advances in quality, performance, packaging and system integration have been made, the concomitant increase in sensors, actuators, and systems associated with diagnostics, controls, or safety, has resulted in an increase in the number of troublesome electrical contacts. Because current and voltage specifications alone do not provide sufficient information to fully describe the system, switches are generally selected on a trial-and-error basis amongst traditional and unoptimized structures which have changed little over the past 25 years.
Impact is a prominent phenomenon in many electro-mechanical systems. Thus in order to correctly simulate and design these systems, impact must be modelled correctly. The solution depends significantly on the hypothesis that is adopted regarding the nature of the collision.
Through a simple example problem that considers a two-link pendulum striking a flat surface, Kane and Levinson [1] pointed out that the classical solution of rigid body impact problems using Newtonian mechanics produces energetically inconsistent results. As evidenced by the recent publications, Kane and Levinson's remarks sparked a remarkable interest in a problem that was thought to have been solved a long time ago. Keller [2] attributed this paradoxical behavior to slip reversals during collision subject to frictional effects. The Newtonian approach ignores the changes in the direction of slip, leading to the overestimation of the rebound velocity as a result of impact [2,3]. Keller introduced a revised formulation of rigid body collision equations based on Poisson's hypothesis that impact never increases energy. Yet, Stronge [4] has exposed energy inconsistencies in solutions using Poisson's hypothesis when the coefficient of restitution, e, is assumed not to depend on the coefficient of friction. He divided the energy that is dissipated during collision into two portions: dissipation due to frictional impulse and dissipation due to normal impulse. Then, he demonstrated that Poisson's hypothesis does not lead to vanishing dissipation due to normal impulse when the coefficient of restitution is unity (perfectly elastic impact). Stronge proposed an ''energetic'' definition for e. This definition equates the square of the coefficient of restitution to the ratio of elastic strain energy released at the contact point during restitution to the energy absorbed by deformation during compression. Shabana and Gau [5,6] examined the effect of the topological change in the propagation of longitudinal elastic waves in mechanical systems. The application of the analysis presented is demonstrated using a rotating rod that is subject to an axial impact by a rigid mass moving with a constant velocity. On the experimental front, Yigit et al. [7] verified the validity of using the algebraic generalized impulse momentum equations of a radially