Structural dynamic tests conducted under SBIR Phase I on a full scale F-15 vertical tail subassembly with piezoactuators showed that buffet could be controlled. The modal characteristics established from the subassembly tests had yielded results correlating well with those from the tests performed on an operational F-15 aircraft. The test identified vibration modes of concern. Controllers which would suppress vibration at specific frequencies and modes were designed, and the structural response to exciting loads at 39.8 Hz, for example, was alleviated by about 40%. Also, nonlinearities in the structural response were identified, and these could be critical for buffet alleviation investigations. Under Phase II, the range of structural response modes which need to be addressed for buffet control over the flight envelope would be tackled by optimally designed multiple piezoactuators and sensors including their weights and locations. Sensor averaging as well as robust control techniques based on Lyapunov functions will be applied for controller design and implementation. Static controllers such as stiffening patches have been shown not to be effective for buffet control. Additional weight of the structure will also be minimized through analysis and experiments, thereby ensuring adequate control of buffet and enhancement of system life.
Keywords: Epic Hydrocode Computer Simulation Cray 3d Armaments Parallel Computing
