Non-linear vibration behavior of thin multilayer diaphragms

The vibration spectrum of piezoelectrically driven (ZnO) thin silicon diaphragms in the driving frequency range up to 100 kHz has been studied. The response of the structure on the driving conditions (a.c. voltage amplitude and frequency) is presented. The limits of the linear plate theory and specific non-linear effects rue discussed. Non-linear effects in the vibration behavior occur for vibration amplitudes even smaller than 4% of the diaphragm thickness. Superharmonic, harmonic and subharmonic vibration modes are observed. The vibration amplitudes of the subharmonic modes are of the same order as the diaphragm thickness. The characteristic non-symmetric resonance peaks of the subharmonic vibration modes indicate the existence of a hard-spring effect in the system. In the case of a system with a hard-spring effect, the concept of vibration modes with fixed resonance frequencies fails. (C) 1999 Elsevier Science S.A. All rights reserved.