Mechanics of 1-3 piezocomposites subjected to creep-fatigue loads

1-3 piezocomposites are extensively used for sensor, actuator, naval and aerospace applications owing to their enhanced electromechanical coupling, wider bandwidth and reliability. However, their performance gets adversely affected when they are subjected to combined static and dynamic loads that initiate both creep and fatigue damage, simultaneously. 1-3 piezocomposites undergo damage due to creep-fatigue interactions because of the passive and viscoelastic polymer matrix and inherent domain switching mechanisms. In this work, experiments are conducted to obtain the electromechanical response of 1-3 piezocomposites subjected to electrical fatigue and mechanical compressive creep loads. It is observed that, the electromechanical response degrades with increase in number of electrical fatigue cycles, matrix volume fraction and mechanical compressive pre-stress. A nonlinear phenomenological combined creep-fatigue damage model is developed within a thermodynamic framework to account for the creep-fatigue interactions in 1-3 piezocomposites. The model predictions are found to be in agreement with the experimental observations.