Modeling piezoelectric pvdf sheets with conductive polymer electrodes
Lediaev, Laura Marie
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The main concern of my research has been to find a good way to solve for the behavior of piezoelectric devices that are electroded not with metal electrodes (as has traditionally been the case) but with a conductive polymer material which has a much lower conductivity compared to metal. In this situation, if a time-varying voltage is applied at one end of the electrode, the voltage cannot be assumed to be uniform throughout the electrode because of the effects of resistivity. Determining the voltage in the electrodes as a function of time and position concurrently with the mechanical and electrical response of the piezoelectric material presents an added complexity. In this thesis the problem of the piezoelectric monomorph is considered. The piezoelectric sheet is PVDF, and the electrodes are PEDOT-PSS. As a first approximation the two problems of finding the voltage in the electrodes and the mechanical deformation in the piezoelectric material are decoupled. In order to determine the voltage distribution in the electrodes, the piezoelectric effects were neglected, which reduced the piezoelectric problem to a capacitor problem. Once the voltage function was determined the mechanical deformation of the PVDF sheet was calculated given the known voltage distribution as a function of position and time.