11 July 2001 Closed cracks in piezoelectric media subjected to electric field
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The conventional traction-free models for insulating and conducting cracks in piezoelectrics predict that an electric field induces zero stress intensity factors at the crack tip. This fails to explain the experimentally observed growth of both insulating and conducting cracks under electric field. To remove the discrepancy between theory and experiments, electric field induced crack closure is considered in this study. Conditions for crack closure are derived by using the solutions for traction-free models. Mixed boundary value problems for closed cracks (insulating and conducting) are formulated using the extended Lekhnitskii's formalism for piezoelectric solids. Analytical solutions are derived for both cases of closed cracks. The present solution predicts that electric loading can induce non-zero (positive) mode-I stress intensity factor at an insulating or conducting crack. The intensified tensile stress directly ahead of the tip of a closed crack can give rise to crack growth. This offers a possible explanation for the experimental observations. Additionally, the effect of polarization switching on the crack tip behavior of both insulating and conducting closed cracks is investigated. Numerical studies show that polarization switching may enhance or decrease the intensity of tensile stress ahead of a closed crack.
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Xianwei Zeng, Xianwei Zeng, R. K. Nimal D. Rajapakse, R. K. Nimal D. Rajapakse, "Closed cracks in piezoelectric media subjected to electric field", Proc. SPIE 4333, Smart Structures and Materials 2001: Active Materials: Behavior and Mechanics, (11 July 2001); doi: 10.1117/12.432761; https://doi.org/10.1117/12.432761

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