<title>Fabry-Perot strain sensors for noise control applications</title>

Abstract

The use of white-light interferometric multimode fiber-optic strain sensors is experimentally assessed within a new strategy involving discrete strain sensing for the active control of the radiated sound power. Each strain sensor uses a Fabry-Perot sensing interferometer and a Fizeau cross- correlation interferometer so that the output signal is directly related to the absolute measured strain. 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 differences scheme, and a wavenumber 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 wavenumber transform of the structural strain. In both approaches, the wavenumber transform is performed over the supersonic (radiating) components of the structural information. Both approaches for using the strain information are implemented into a multi-channel filtered-X LMS algorithm to perform the active control of the sound power radiated from the beam. Experimental results obtained using four strain sensors and both control approaches show that fiber-optic strain sensors and PVDF strain sensors provide similar and good control performance.