Research Of Piezoelectric Bending Effect For Quartz Crystal And Its Application

Piezoelectric materials have been used widely and their effects have been investigated in detail with the development of science and technology, however, the researches of piezoelectric bending effect only stay on the level of experiments and measurements. Considering this situation, this paper theoretically explains the existence of piezoelectric bending effect and designs one kind of monolithic micro-vibration actuator based on this theory.This project is supported by the National Natural Science Foundation of China (No.69774020) and the Scientific Research Foundation on Doctoral Subject of the Ministry of Education (No.98014106 & No.20010141006). From the application aspect of engineering, interdisciplinary knowledge, such as Physics of Crystals, Physics of Dielectrics, Theory of Elasticity, Piezo-electricity is utilized in the investigation on the piezoelectric bending effect of quartz crystal. The inner stress distribution of quartz rod is investigated firstly by using the pure bending theory of anisotropic beam, and numerical solution is approached. The inner electric polarization field is deduced by using piezoelectric equation. Considering the equivalent principle of electric field, the distribution of equivalent body and surface bound charges is also deduced. The existence of direct piezoelectric bending effect of quartz crystal is verified by boththeory and experiment. Based on a monolithic Y00 cut quartz crystal bar, this paper discusses the converse piezoelectric bending effect and deduces a theoretical linear relationship between the deflection at the tip of the beam and the driving voltage. This part of work establishes the relationship between electricity and mechanics. Therefore it presents a method on investigating piezoelectric bending effect.On the base of the mathematical bending effect model, this paper also optimizes the single rotated crystal cuts, and designs a monolithic micro-actuator, which can vibrate in both X and Y directions, used in micro-carving, considering the following factors, such as single vibrating mode, piezoelectric activity, zero temperature coefficient etc. Finally, this thought is verified to be feasible by a qualitative experiment.The accomplishments of this paper would supplement and improve piezo-electricity and establish the basis for fabricating piezoelectric monolithic body actuators.