The objective of this work is to develop a method for placement of a single shunted piezoelectric patch to dampen several modes of plate vibration. This goal is accomplished by maximizing the generalized electromechanical coupling coefficient while limiting eigenvalues for the modes under consideration. The variation introduced is the location of the center of a square piezoelectric patch. The difficulty in finding the optimai location of the patch is rooted in both the vastly different mode shapes of the plate in this study and the fact the piezoelectric stiffness is frequency dependent and the frequency is dependent on the location of the piezoelectric. A method based on determining the maximum objective function due to a user-specified relationship between the modes of vibration of a given plate is presented. A small plate and an electrical chassis box bottom plate are used as optimization examples. The method developed is highly adaptable to changes in structural design, material changes and changes in the relative importance of the modes of vibration.

The effects of composition, magnetic annealing and texture on the magnetic properties, magnetostriction, and core noise of pilot-produced 6.5% Si–Fe sheet and transformer cores have been studied and the results compared with the core-loss and core-noise characteristics of domain-oriented 2V-CoFe and cube-textured 3% Si–Fe transformer cores. The application of magnetic annealing reduced magnetostriction of 6.5% Si–Fe sheet to 1×10−6 at 18 kG. The use of a low-magnetostriction core material, such as 6.5% Si–Fe, was shown to result in a considerable reduction in transformer core noise, reducing in turn the maximum noise level of a 3-phase, 400-Hz, 1250-VA static inverter to 50 dB in an acoustic frequency range of 0.4–20 kHz.