Hysteretic electro-mechanical coupling response of PZT fibers: Constitutive modeling and experiments

Piezoelectric (lead zirconate titanate, PZT) fibers show hysteretic behavior when subjected to cyclic mechanical loading, under tension, and cyclic electric field. The hysteretic response under the above loading conditions is manifested due to microstructural changes such as reorientation of dipolar domains in the crystalline regions and other possible permanent microstructural changes such as cracking. In describing the above macroscopic behavior of PZT fibers a constitutive model based on a multiple natural configuration approach is formulated. It is assumed that the body has multiple natural configurations associated with the original and newly formed configurations. The new microstructure is formed when the body is subjected to external stimuli, i.e., stress and electric field, leading to reorientation of the dipoles in the crystalline regions. A constitutive model for the electro-mechanical coupling behavior is formulated by defining Gibbs potential in terms of the stress, electric field, and the volume fraction of the domain transformation. Internal state variables and their corresponding driving force for microstructural changes are identified. The model predictions of the hysteretic response are compared to experimental results. Finally, the effect of heat generation from the energy dissipation on the overall electro-mechanical response of PZT fibers is investigated.