Time dependence of piezoelectric d33 coefficient of cellular piezoelectret polypropylene film: Finite element modeling

In this article, the effective piezoelectric d33 coefficient of cellular piezoelectret polymer film is simulated by means of the finite element method. The cellular piezoelectret film is regarded as a periodic material, where the almost ellipsoidal voids produced by biaxial stretch are considered to be scattered periodically. The hollow oblate tetrakaidecahedron is used to model the charged microvoids. The polymer is take to be isotropic and viscoelastic. Representative volume element is adopted and the periodic boundary conditions are implemented. The electrostatic field coupled to the stress through the Maxwell stress tensor is analyzed. The piezoelectric d33 coefficient in the film thickness direction is phenomenologically defined and numerically obtained. Time dependence of the effective piezoelectric d33 coefficient is presented for different void geometrical parameters.