STABILIZATION OF CANTILEVERED FLEXIBLE STRUCTURES BY MEANS OF AN INTERNAL FLOWING FLUID

An active vibration suppression technique for flexible structures is proposed and practically implemented. The technique is based on the fact that an internal flowing fluid can stabilize the structure by dissipating vibrational energy. The particular structure studied is a cantilevered tubular beam where the fluid speed is less than the critical flutter speed. The proposed technique provides a distributed actuator for vibration suppression being free from the spillover phenomenon often encountered in structural control. By way of demonstration, an experiment with a hanging tubular structure and a control system has been set up. The latter consists of a noncontact-type displacement sensor, a one-chip microcomputer and an electronic valve. Open-close operation of the valve is controlled by the microcomputer. The valve is opened for an internal flow to damp out the disturbed motion, and closed to cut the flow off after the motion is damped out. The experimental system thus possesses some primitive features of an intelligent structure. The effectiveness of the proposed vibration suppression technique is verified by the experiment.