Active Structural Acoustic Control of a Launch Vehicle Fairing Using Monolithic Piezoceramic Actuators

This study investigated the feasibility of using active structural acoustic control with monolithic piezoceramic actuators to reduce the low frequency noise transmission through rocket fairings during launch. Closed-loop simulation results are presented using a fully coupled structural acoustic model of a lightly damped composite fairing structure with integrated piezoceramic actuators. Constraints were placed on controller mass and maximum allowable actuator voltage in order to provide a baseline of reasonable expected performance. Realistic disturbance levels were used in the simulations, and two disturbance cases were considered with significantly different spectral characteristics. Simulations were conducted to compare the effects of actuator thickness, covered surface area, and maximum actuator voltage on controller performance and energy requirements. Linear Quadratic Regulator control laws were computed assuming full-state feedback using three design approaches. The results provide significant insight into the noise transmission problem and to the physical dynamics of the control approach. The best-case reduction in the spatially averaged interior acoustic response was determined to be approximately 2.5 dB over the 0-300 Hz bandwidth.