Elucidation of the “jumping and dropping” phenomena of piezoelectric vibrators in high-amplitude operations in the vicinity of their mechanical resonance frequencies

The peculiar events called the “jumping and dropping” phenomena of piezoelectric ceramic vibrators in high amplitude operation have been widely known. The phenomena, that occur solely in the vicinity of the mechanical resonance frequencies of the vibrators, are due to the emergence of hysteresis in the frequency domain with an abrupt increase and decrease of the vibratory amplitude. It has long been believed that the nonlinearity of the piezoelectric materials is the dominant cause of the unstable vibratory behaviors. Nevertheless, the authors have found that they can be attributed to the local piezoelectric polarization reversals due to the electric field concentration caused by its conspicuous distortion inside the vibrators in mechanical resonance. This hypothesis has been examined by numerical and experimental investigations for hard-type piezoelectric ceramic disks vibrating in axisymmetric radially pulsating mode.