Measurement of static strain distribution using piezoelectric polymer film (principle and application to a holed plate)

The objective of the present study is to exploit the feasibility of piezoelectric polymer film sensors to evaluate in-plane static strain distributions of structural components. In contrast to ordinary use of piezoelectric films as strain and strain-rate sensors detecting electric charges or currents in a closed circuit, the proposed strategy consists of directly measuring the distribution of electric potentials induced in the piezoelectric film mounted on the surface of a deforming structural component. Strain distributions are determined from the measured potentials taking into account the piezoelectric constitutive law of the film material. As an illustrative example, thin films of polarized polyvinylidene fluoride (PVDF) are mounted on a holed elastic plate subjected to in-plane loading, and the induced potential distributions are measured on the film surface by an electrostatic voltmeter. It is demonstrated that the determined strain distributions are in fair conformity with those predicted by the theory of linear elasticity.