The Investigation Of Multi-Piezoelectric Effect And The Application On Sensoriactuators

This work was supported by Doctor Subject Foundation of the Ministry of Education of China under Grant No. 20010141006, namely "The investigation of the electro-mechanical coupling multi-induced effect and application on sensoriactuators."Since Curie brothers discovered the piezoelectricity of quartz crystal in 1880, the research on piezoelectric effect has already expanded from the 2-dimensional effect based on stress analysis, namely the longitudinal effect, transverse effect and sheer effect to the 3-dimensional effect based on the deformation analysis, such as the extending effect, compressing effect, bending effect and torsional effect. The above effects belong to first piezoelectric effect. With the technology development and practical engineering requirement, the further study of theory and application of multi-piezoelectric effect is needed because induced electric field and induced strain of the multi-piezoelectric effect are more and more miniature. The new concept of multi-piezoelectric effect is firstly proposed by Professor Sun Baoyuan in 1999. Among the documents reported overseas and domestically, there is a little research on the secondary piezoelectric effect and there is no research on the application of the secondary piezoelectric effect and the theory and application of the multi-piezoelectric effect.This paper analyzes the relationship between the first, secondary and multi-piezoelectric effect and the mechanical and electric boundary conditions of the crystals. Only when the corresponding boundary conditions are satisfied, the multi-piezoelectric effect can occur. If the piezoelectric material is regarded as the thermodynamic system, the linear relation between the main effect and cross coupling effect of the three kinds of energy, the four kinds of energy and the six kinds of energy is analyzed. The similarity of the piezoelectric effect and the electromagnetic effect is also analyzed, and the result proves that they both have bilateral reversible effect and the secondary, third and multi-induced effect.The theoretical investigation of the multi-piezoelectric effect based on first direct and converse piezoelectric effect is conducted and the mathematical expressions of multi-piezoelectric effect are established. At the same time the influences of multi-piezoelectric effect on dielectric constant, equivalent capacitance, elastic constant, Poisson's Ratio and piezoelectric constant are analyzed.