Finite element simulation of steady‐state heat problem in electrostrictive vibrators

Ultrasonics is utilized widely for industrial application. An electrostrictive transducer is used widely for this purpose because of its high electromechanical conversion efficiency. In actual use, the transducer usually is operated under the mechanical vibration of large amplitude, and the mechanical loss of the vibrating body is responsible for the heat. Since the transducer is also excited at high voltage, the dielectric loss in a ferroelectric body must be considered for the heat. These losses should be taken into account in the design. However, the temperature distribution and the influence of the temperature caused by the heat are not always clear. The heat design of the transducers depends on the experiments which at present, are made on a trial-and-error basis. This paper describes the application of the finite element method to simulating a steady-state heat diffusion problem in electrostrictive vibrators. The simulation is made to evaluate the temperature distribution caused by the heat which is generated by the mechanical vibratory loss in the elastic body and the dielectric loss in the ferroelectric body, and then the influence of the temperature distribution on the transducer characteristic is examined. Simulation is an experiment on computer and could be used as a means of CAD. Among others, the capability of the visualization of the temperature distribution and the thermal stress distribution helps to design the ultrasonic transducers. A numerical demonstration is made whose results are compared with the experimental results. The technique is proved to be useful in solving problems of this kind.