Nondestructive evaluation of thickness variations for elastic plates by high-overtone bulk acoustic resonance

Based on the resonant frequency spectra of a high-overtone bulk acoustic resonance, a model for nondestructive evaluation of the elastic plate thickness is given. The simulations demonstrate that the thickness deviations of the elastic plates are sensitive to two parameters: the parallel resonance frequencies and the spacing of parallel resonance frequencies (SPRF). At the normal and transition regions of the SPRF curves, the parallel resonance frequencies periodically linearly decrease with the increase of thickness deviations, which is applicable for evaluating the thickness deviations of the plates.