Resonance contour oscillations of a piezoceramic plate with automatic frequency control

Abstract

The resonance harmonic mode is one of the most commonly encountered operating mode of piezoceramic elements. In this mode the dissipative properties of the material manifest themselves rather strongly, in the form of dielectric and, especially, mechanical losses. Depending on the duration and level of load, the head-exchange conditions, as well as because of the heat conductivity of traditional piezoceramics, the hysteresis losses may lead to significant evolution of heat as a result of the conversion of part of the electromechanical energy of the oscillations into thermal energy. As the temperature increases, the resonance frequency shifts from its nominal value and, as a consequence, the amplitudes of the output functional characteristics of the piezoelectric element drops. The resonance mode of oscillations with automatic exciting frequency control may be used to maintain these characteristics at a relatively high and constant level for prolonged load periods without any change in the power delivered to the piezoelectric element. In the present article the problem of oscillations and dissipative heating of a piezoelectric element is considered using the finite element approach under the assumption of automatic exciting frequency control using as an example the case of the contour oscillations of a piezoceramic plate.