ACTIVE CONTROL OF FORCED AND UNFORCED STRUCTURAL VIBRATION

An analytical approach to vibration control is presented, and verified experimentally, for cases where it is undesirable to add actuators wi th significant mass and stiffness to the structure. A linear coupling control (LCC) strategy is implemented by coupling a second order linea r system to an oscillatory plant to create an energy exchange between the two component systems. One of the advantages of this approach is t hat the control strategy is ultimately capable of controlling unforced and periodically forced vibrations in the plant. The paper covers the application of the LCC control strategy to a cantilevered beam actuat ed by piezoceramic actuators. A novel model for the piezoactuated beam is derived for any representative mode, resulting in a set of lineari zed equations. Also, the model provides flexibility in actuator locati on and dimensions. The controller is modelled as a single-degree-of-fr eedom linear oscillator which is coupled to the plant via linear terms . The result is a small actuating force, or weak coupling between plan t and controller which lends itself well to piezoceramic actuation. Th is system is solved as a linear eigenvalue problem which provides a co mputationally efficient means of finding the response. The solution is also verified by means of a finite element (FE) simulation which is c arried out for both free and forced vibration. Apart from confirming t he theoretical model and closed-form solution, the FE method provides another flexible means in predicting the response of the LCC strategy, the control strategy and the theoretical studies have been verified e xperimentally. (C) 1997 Academic Press Limited.