ACTIVE STRUCTURAL ACOUSTIC CONTROL USING STRAIN SENSING

A new strategy based on the direct use of strain sensing is proposed f or the minimization of the acoustic radiation from a vibrating plate. This strategy uses active structural acoustic control because it elimi nates the need for far-field acoustic sensors. The cost function is de fined as the radiated acoustic power and the discrete strain informati on is given directly, for example, by fiber optic sensors embedded in the structure. Two approaches are presented to express the cost functi on in terms of strain information. The first one is based on plate's d isplacement reconstruction from the strain field while the second is b ased on integration by parts of the wave-number transform of the displ acement. Proper concentration of the control effort is obtained with t he cost function defined in the wave-number domain. Both approaches ar e first validated with respect to an analytical solution for the calcu lation of the radiated acoustic power from structural strain informati on. It is shown that good agreement is obtained with at least two stra in sensors per structural wavelength. Optimal control of acoustic radi ation from a simply supported plate is then performed using different configurations of sensors and actuators. The control is performed usin g simulated piezoelectric actuators and results show that both approac hes are well suited for active control applications as they offer good performance over a wide frequency range while requiring only few sens ors. (C) 1997 Acoustical Society of America.