A cohesive zone model for the electromechanical damage of piezoelectric/ferroelectric materials

A numerical fracture analysis of piezoelectric and ferroelectric materials is conducted using an advanced exponential cyclic cohesive zone model. The implemented irreversible cohesive law allows for the damage accumulation during subcritical electromechanical loading. Change in polarization direction (as a result of ferroelectric domain switching) due to applied electromechanical loading is taken into account. A generalized capacitor model representing the permittivity of the grain boundaries or cohesive elements is implemented in the cohesive law. Due to the presence of cohesive elements, a specimen can experience instability of the equilibrium response path. Therefore, post-peak strain-softening constitutive relations are investigated to handle the snapback effect. Numerical simulations are performed for a 3D basic test model as well as for a ferroelectric actuator. The observed results reflect a realistic influence of the electric field as well as domain switching on the fracture of the specimen. Mechanisms of damage initiation and accumulation are illustrated in the piezoelectric/ferroelectric medium under cyclic electric loading.