Vibration response of an elastic disc excited by a piezoelectric disc

This paper presents the vibration response of an elastic disc that is harmonically excited by a piezoelectric disc in an ultrasonic sensor structure. The ultrasonic sensor comprised an elastic disc combined with a cylindrical wall and attached to a small piezoelectric disc. The vibration response must be maximized by selecting the radius ratio and thickness ratio of the piezoelectric and elastic discs. Vibration distribution is necessary for analyzing the acoustic characteristics of ultrasound radiating from an ultrasonic sensor for distance measurement. The response equation for an elastic disc with a fixed boundary was theoretically obtained by considering the harmonic excitation of the piezoelectric disc. The vibration response distribution of the elastic disc coupled with a cylindrical wall was analyzed using finite elements to enhance the theoretical result. Experiments were performed to confirm the response distribution by exciting a piezoelectric disc in an enlarged specimen of an ultrasonic sensor structure. At the first natural frequency, the radius ratio of the maximum amplitude was 0.61, and the thickness ratio of the maximum amplitude approached zero.