ACTIVE CONTROL TECHNOLOGY APPLIED TO ROCKET FAIRING STRUCTURAL VIBRATIONS AND ACOUSTICS

Future launch vehicle payload fairings will be manufactured from advanced lightweight composite materials. The loss of distributed mass causes a significant increase in the internal acoustic environment, causing a severe threat to the payload. Using piezoelectric actuators to control the fairing vibration and the internal acoustic environment has recently been proposed. The control authority of these actuators for this problem has not yet been determined. To help determine the acoustic control authority of piezoelectric actuators mounted on a rocket fairing, the internal acoustic response created by the actuators needs to be determined. The internal acoustic response of a closed simply-supported cylinder actuated by piezoelectric actuators can be conveniently determined by using the Kirchoff-Helmholtz integral and the cylinder's spatial surface velocity. The surface velocity is determined using an impedance model of an actuator bonded to the surface of a cylinder. The structural analysis is compared to an experiment and the results are in agreement. The acoustic formulation is described along with a description of future work. The work presented provides the initial steps required in determining the acoustic authority and feasibility of using piezoelectric actuators on rocket fairings.

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