Piezoceramic active vibration-suppression control system development for the B-1B aircraft

Abstract

An active vibration suppression system (AVSS) was designed and flight tested on a B-1B aircraft aft fuselage skin panel subjected to engine noise and unsteady flow induced vibrations. This was the first time an AVSS was successfully demonstrated in flight on a high performance combat aircraft. The purpose of the feasibility test was to confirm that an AVSS could significantly reduce structural vibrations and still survive in an aircraft service environment with a severe acoustic field. The system used piezo-ceramic (PLZT) patch type actuators developed by the Rockwell Corporation, that demonstrated superior performance relative to commercial PZT's. The active system using H- infinity control laws was developed to maximize the force generated by each PLZT actuator and to minimize the micro- processor processing time and control system instabilities. PLZT coupon tests were used to determine the size, shape, and thickness of the PLZT and to test epoxies and the epoxy bonding thickness that will give the best performance under the flight environmental conditions. Three micro-processing boards were considered to minimize the processing time and two boards were tested before the final selection was made. The hardware were designed, wired, and tested in a laboratory acoustic tunnel on a flat plate and on a curved panel that simulated the B-1B aft fuselage panel. The laboratory test showed the PLZT patches could drive the curved panel to similar g levels as on the aircraft. The lab tests also showed the response of the first mode could be eliminated with the active controller. The resulting system design was installed and flight tested on a B-1B aircraft aft fuselage skin panel that is subjected to jet noise. The system was successful in reducing the fundamental panel vibration modes as much as 79 percent for the takeoff conditions and about 46 percent for transonic flight conditions, with 25 percent response reductions for a higher order mode. The paper presents a discussion of the control system development and the active vibration suppression system performance.