| The first study for intelligent materials is its nature. PVDF thin films because of its good piezoelectricity, pyroelectricity is widely used for the production of piezoelectric sensor and pyroelectric sensor. But the research of the internal nature is not enough, therefore, the precision of the sensor with PVDF film as sensitive element has a large promotion space, at the same time, because of various sensor working environment is complex, and vulnerable to all kind of physical field, so,this paper use PVDF film as the research object, analyze and study the coupling characteristics of it in the heat, mechanics and electricity even the magnetism field.First, as a typical piezoelectric materials, the piezoelectric properties of PVDF thin film have been studied widely and deeply. If we want to research on its coupling field, we need to derive the equation of correlation. The paper deduces PVDF film constitutive equation, the coupled equation etc. At the same time PVDF film also have excellent pyroelectric properties, but there has been little research on the electrical characteristics of heat release, so the paper introduce and analyze the puroelectric properties presently, and deduce the PVDF thin film pyroelectirc equation, combined with the piezoelectric equatons, the paper deduce the heat-power-electrical coupling equation of PVDF thin film. In order to facilitate the finite element analysis, the paper change the couple constitutive equations into the differential equations. At the same time, the paper also deduces the equation of cectromagnetic thermal coupling field research to facilitate later.Secondly, the paper analyze the coupling mechanism of PVDF thin film, and choice the finite element method, use COMSOL Multiphysics program to analyze the response on situation of PVDF film in the temperature field,stress field and the effect.Again, the paper analyze the the response in the heat- power-electric coupling field under the action of the PVDF films were analyzed using COMSOL programming software, and the response of its and the thermal and mechanical coupling and a single physical field comparison, further analysis of the coupling field properties of PVDF film.The last part of the paper is the real test, discussed the influence of temperature field, stress field, electric field for PVDF thin films. Design the experimental platform, data acquisition system and the follow-up processing circuit and analyzed the test and data.The conclusions of the paper are as follows:This paper deduces the equation of PVDF thin film pyroelectric, piezoelectric equation and the thermo piezoelectric coupling equation; on this basis, using the finite element software COMSOL Multiphysics coupling behavior of PVDF thin film were in heat, stress, electric field and the load on the thermal stress and thermal-Mechanical-electric loads are simulated. The results showed that:the strain and the potential on the PVDF film alone under the action of the impact is the biggest is load and thermal load, and minimum influence of electric load, but when the electric load and other load coupling occurs, will make the strain and the potential response becomes complex. For a clamped PVDF film, with a uniformly distributed load, the strain occurred mainly in the center of the circle, and its maximum potential in the 1/2 radius. In the case of coupled thermal stress under article respectively by ANSYS and COMSOL Multiphysics on the simulation, the results show that the article adopts the method of consistent, reliable. The article also on the frequency response of PVDF films do experiments, the results show that the PVDF film has an excellent performance in the detection of low frequency signal. |
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