Investigation of orientation effects on the electro-mechanical coupling behavior of 1–3piezoelectric composites under compression

Abstract

The electro-mechanical responses of 1–3 piezoelectric composites with PZT5A1fibers embedded in an epoxy matrix are investigated under compressive loading.When the applied loading direction is not parallel to the polarization and fiberdirections of the PZT fibers, the corresponding electrical and mechanical responsescan be dramatically affected. Here both experimental testing and theoreticalmodeling are carried out to study such orientation effects on 1–3 piezoelectriccomposites. The testing results indicate that, as the loading direction changes from0°,to 30°, 45°,60° andfinally 90° to the initial poling direction (which is also the PZT fiber direction),the magnitude of the electric displacement and mechanical strain of thesystem all decrease and the electrical response will diminish to zero at90°. On the other hand, a two-level micromechanics theory based on irreversiblethermodynamics and the physics of domain switching is applied to predict suchorientation dependency of the electro-mechanical coupling behavior of the compositesystem. The first level is based on PZT fibers only which consist of parent andswitched domains due to external loading, and the second level is based on a largerscale consisting of PZT fibers and an electrically inactive polymer matrix. Thetheoretical results are found to be in reasonable agreement with our experimental data.