Experimental results on active structural acoustic control using fiber-optic strain sensors

Abstract

A new strategy for the active control of the sound power radiated from a flexural vibrating beam is experimentally investigated. This strategy involves sensing the discrete structural strain using white-light interferometric multimode fiber-optic strain sensors. Two approaches are used to relate the radiated sound power to the structural strain. The first approach is based on the reconstruction of the transverse structural displacement field from the structural strain field using a finite-difference scheme, and a wave-number transformation of the structural displacement to obtain the radiated sound field. The second approach is based on an exact expression directly relating the radiated sound field to the wave-number transform of the structural strain. In both approaches, the wave-number transform is performed over the supersonic (radiating) components of the structural information. The dynamic strain measurements are first compared with polyvinylidene film strain sensors. As a second step, a straightforward control scheme is implemented into a multichannel filtered-x LMS algorithm to control the strain amplitudes on the beam actively. Finally, both strategies for using the strain information are implemented to perform the active control of the sound power radiated from the beam. Preliminary performance results of both strategies using four strain sensors are then presented.