Force - Thermo - Electrical Coupling Field Analysis Of PVDF Piezoelectric Element

As J.Curie and P.Cureie firstly proved crystal has piezoelectric effect caused by external force in1880, the researches about piezoelectric coupling mechanism of piezoelectric materials has not been finished, but the piezoelectric coupling mechanism of piezoelectric materials are still not clear,so it is so essential to do researches about piezoelectric coupling mechanism. So this article about physical fields under the action of force thermal-electrical coupling of PVDF piezoelectric polymer was studied.First of all, the relevant force-therm-electrical coupling constitutive equation is derived with the related theory involves piezoelectric attitudes including factors of the stress, strain and electric potential, the electric displacement and temperature, At the same time, because of PVDF piezoelectric material having the characteristics of anisotropy, according to this characteristic this constitutive equation can be converted to dynamic differential control equation for application, then the equation of mechanical and electrical boundary conditions is presented. Finally the main works are finished as followings:1) The research of PVDF piezoelectric polymer force-electricity coupling effect has been done. With providing mechanical and electrical boundary conditions, the analysis of piezoelectric material’s coupling characteristics under the power load, the electric load has been finished by the way of finite element analysis which deponds on ANSYS;2) Considering the influence of the temperature field, the coupling field caused by temperature load changes had been determined. The analysis on the influence of PVDF piezoelectric polymer under the temperature gradient changes is mainly completed, moreover the thickness of the PVDF material would change its response in the temperature field have been analyzed;3) Mainly establish an force-thermal-electrical coupling field finite element dynamics equations based on the theorys of higher-order displacement field and higher-order temperature field, and by using the ANSYS, the voltage performance of PVDF piezoelectric beam structure under force-thermal-electrical coupling process are solved and analyzed, eventually concluded the PVDF’s coupling characteristic in the impact force of the force-thermal-electrical coupling field;4) From the view of actual test, this chapter focuses on the force-thermal-electrical coupling fields’experiment scheme, developing data processing system, and carries on the system test and data analysis, according to force field, temperature field and thermal field’s efforts to piezoelectric performance parameters of PVDF piezoelectric polymer.Conclusion summed up as: This passage establishes force-thermal-electrical coupling mathematic model, and gives mechanical, electrical and thermal boundary conditions; Thermal influence to the natural frequencies of PVDF piezoelectric analysis can be ignored; PVDF piezoelectric polymer force-thermal-electrical coupling characteristic is nonlinear, and When temperature field or electric field effect is larger, the performance of PVDF piezoelectric wafer is affected by temperature field or electric field much more strongly.