An Estimate of the Effective Size of a Normal Probe's Piezoelectric Plate

The directivity characteristic of a normal probe with a circular piezoelectric plate has been calculated with allowance for pressure (elastic stress) oscillations within both the excitation region (the surface of the electrodes applied to the piezoelectric plate) and the plate itself, whose dimensions exceed those of the excitation region. It is established that, in the first and second cases, the directivity characteristics are somewhat wider and narrower, respectively, than those used in the conventional stepwise approximation of the pressure applied from a transmitting probe to the surface of a tested article. The effective piezoelectric-plate size is estimated. [Ceramics were the materials tested].