Piezoelectric Laminate PVDF Using In Active Structural Acoustic Control

The method of active structural Acoustic Control (ASAC) developed in 1980s is a new method to control noise caused by vibration structure. The control method based on the radiation modes of radiation structure is a new one developed in recent year. It can be used in analyzing the behavior of sound field caused by the vibrating body. In this paper, it is presented radiation modes and corresponding radiation efficiencies using relationship between surface normal velocities and surface sound pressure of vibration structures. And one definition is given to the weight coefficient of sound radiation. Because of radiation modes orthogonal to one another, so the sound power of each radiation modes is completely independent of one anther. Radiation modes are dependent on the radiator geometry and frequency, but not on any material characteristic of the radiator itself. And the radiation efficiencies of their radiation modes is fall off very rapidly with the increase of modes order at low frequencies. Based on these observations, radiation modes of planar structure are analyzed in detail.It is important in ASAC based on the radiation modes of radiating structure to get weight coefficients of sound radiation. Based on the control strategy that minimize sound power by canceling the weight coefficients of sound radiation modes k modes, it is made to design the shape of PVDF, in order to measure the corresponding weight coefficient of sound radiation. In this paper, two method for designing the shape of PVDF are present: in term of structure model and in term of sine and cosine. The last method is available in arbitrary boundary and arbitrary velocity.In order to validate the method, one experiment is being conducted with the simply beam, the fix beam and the cantilever beam, as the subject to measure model 1 and model 2 weight coefficient of sound radiation model. From the data of experiment it is proved that the PVDF error sensor is available in measuring the coefficients of sound radiation model, and the method in team of Fourier series could be made to design the shape of PVDF in arbitrary boundary and arbitrary velocity.