Active structural acoustic control of a clamped-free beam by means of modal reduction

Nowadays noise pollution has become an important environmental concern due to the uncomforting and health problems it causes. The aim of the work presented here is to reduce the sound radiation of a cantilever element by means of an Active Structural Acoustical Control (ASAC) system. These boundary conditions appear a lot in the industrial machines and there has not been as studied in the literature as simply supported elements. Specifically, a simplified model, which simulates the clamped element by means of a clamped-free beam, is presented. In order to control the first three modes a single-input single-output control strategy has been achieved using an "Acceleration Feedback Control" (AFC) with three two-order compensators. The selected actuator has been of a piezoceramic stack type, placed in parallel to the neutral axis of the controlled beam to induce bending moments. As a main result of this work, a more than 50% reduction of the sound radiation amplitude of the beam has been accomplished.