Experimental Evaluation of a Semi-Active Friction Damper

Abstract

Semi-active control of friction dampers has been proposed to improve the energy dissipation characteristics of passive friction dampers and to broaden the areas of application in which they can successfully be used. In this paper, we implement a control law which maximizes energy dissipation in an instantaneous sense by modulating normal force at the friction interface. This control law is valid for friction models with and without velocity dynamics. Using experimental results, we demonstrate under what operating conditions friction dynamics are vital to the control problem and, for these conditions, demonstrate the efficacy of the proposed controller. Furthermore, we show that for systems forced at a single frequency, the control law also increases the damper’s slip amplitude. The proposed controller is shown to increase energy dissipated per cycle by up to 200 percent in comparison to the case of constant normal force.