Friction control for vibration suppression

Friction damping in bolted joint connections of large space structures turn ed out to be a major source of damping. For vibration suppression, the join ts are designed such that the normal force in a frictional interface is con trolled which improves the damping performance. The use of active control t o vary the normal contact force in a joint by means of a piezoelectric elem ent is explored. A model consisting of two elastic beams connected by a sin gle active joint is considered. A friction model with velocity-dependent dy namics is used to describe the friction phenomena. A control law for fricti on dampers which maximises energy dissipation instantaneously by controllin g the normal force at the friction interface is proposed. The effect of dis placement- and velocity-induced friction dynamics is considered for the des ign of the control law. We arrive at a controller which prevents frictional energy stored as potential energy in a bristle model from being returned t o the system. (C) 2000 Academic Press.