Accumulation Damage Mode for Ferroelectric Ceramics Subjected to Mode III Fatigue Loading Conditions

Based on the accumulated plastic displacement criterion, equations to predict the fatigue crack growth of piezoelectric ceramics are developed. The medium is subjected to anti-plane mechanical and in-plane electrical loads. Under such electromechanical loading conditions, it is assumed that an electric saturation zone and an elastic yielding zone near the crack tips are developed. The accumulated plastic deformation is obtained in a closed-form, which is expressed in terms of the applied loads and material constants. A fatigue crack growth law of a fourth-power function of the effective stress intensity factor is derived. The effect of electric field load on the effective crack-tip stress intensity factor and crack growth rate are shown graphically.