Volume 120, Issue 3, September 2006
Index of content:
- TRANSDUCTION 
120(2006); http://dx.doi.org/10.1121/1.2228611View Description Hide Description
An experimental investigation of the electromechanical properties of radially polarized thin-walled piezoelectricceramic cylinders as a function of the height-to-diameter aspect ratio is presented. The focus of this investigation is on the lowest order axially symmetric modes of vibration for cylinders with free ends having aspect ratio less than 3 with emphasis on the region of strongest coupling around aspect ratio . The resonance frequencies and coupling coefficients are presented vs aspect ratio and quantify the lower, upper, and an intermediate resonance branch. It is shown that the intermediate branch is flexural in origin and clearly crosses the so-called “dead zone,” which is an inadequacy of the membrane theory applied to the vibration of thin shells [Junger and Rosato, J. Acoust. Soc. Am., 26, 709–713 (1954)]. The coupling coefficient for the lower branch is shown to drop to zero at , whereas the coupling coefficient associated with the upper branch reaches a maximum at an aspect ratio near this region. As an example of the practical application of this study, the performance of two underwater electroacoustic transducers comprised of cylindrical elements having different aspect ratios is reported.
Coupling between thermoacoustic resonance pipes and piezoelectric loudspeakers studied by equivalent circuit method120(2006); http://dx.doi.org/10.1121/1.2225643View Description Hide Description
In order to miniaturize thermoacousticrefrigerators,piezoelectricloudspeakers are used as acoustic sources for operating at high resonance frequencies. An integrated equivalent circuit model of a thermoacousticresonance pipe driven by a piezoelectricloudspeaker is presented to investigate the coupling conditions between the piezoelectricloudspeaker and thermoacousticresonance pipe. Using the equivalent circuit model the optimized coupling conditions can be obtained, with which the highest electroacoustic transfer efficiency and the largest acoustic output power of a piezoelectric acoustic source can be achieved. The theoretical simulations are taken to optimize the structures and the operating frequencies of the thermoacoustic systems.