Vibration characteristics for piezoelectric cylinders using amplitude-fluctuation electronic speckle pattern interferometry

Electronic speckle pattern interferometry (ESPI) is a full-field, noncontact technique for measuring the deformation of a structure subjected to static loading or, especially, to dynamic vibration. Three-dimensional vibrations of piezoelectric materials with cylindrical surfaces are investigated using the amplitude-fluctuation ESPI (AF-ESPI) method. This method demonstrates the advantages of combining noise reduction, like the subtraction method, and high fringe sensitivity; like the time-averaged method. The optical system for AF-ESPI with two in-plane and one out-of-plane measurements is employed to study the volume vibration of a piezoelectric material for a thick circular disk, a ring, and a thin-walled tube. Because the clear fringe patterns measured by the AF-ESPI method will be shown only at resonant frequencies, both the resonant frequencies and the complete vibration mode shapes in three dimensions are obtained experimentally. Finally, impedance analysis and the finite element method are also utilized, and the results are compared with the measurements obtained by AF-ESPI. It is shown that the numerical calculations and the experimental results agree fairly well for both the resonant frequencies and the mode shapes in three-dimensional configurations.