Recently, the theoretical framework of fracture mechanics of piezoelectrics has been extended to include electrostatically
induced mechanical tractions in crack models yielding a significant crack closure effect.1-3 However,
these models are still simple, neglecting e.g. the piezoelectric field coupling. In this work, an extended model for
crack surface tractions is presented yielding some interesting effects. In particular, it is predicted that the Mode-I
stress intensity factor is influenced by both a collinear normal stress parallel to the crack faces and a Mode-II
shear loading. Also, the direction of electric field vs. poling direction is clearly manifested in the calculated crack
loading quantities.
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