A generalized Dugdale model is proposed for a poled piezoelectric [1] plate weakened by a quasi-stationary internal hairline straight crack. The plate is assumed to be mechanically ductile and electrically brittle. The plate is subjected to uniform constant, unidirectional mechanical tension at infinite boundary of the plate. The tension is applied in a direction perpendicular to the length of the crack. Also a unidirectional electric field is applied at infinite boundary along the poling axis of the plate. Two cases are considered: Case I: when the crack lies along the poling axis of the plate; Case II: when the crack lies perpendicular to the poling axis.Due to the applied forces the faces of the crack open in Mode-I type deformation forming an electric saturation zone and a plastic zone at each tip of the crack lying along the axis of the crack. Plate being electrically brittle the electric saturation zone developed at the crack tip along the length of the crack will be smaller then that of the plastic zone developed at this tip of the crack. The plastic zone under the small scale yielding will also develop along the axis of the crack. To arrest the crack from further opening the rims of saturation zone are subjected to cohesive saturation limit electric displacement field and rims of plastic zone are subjected to normal cohesive yield point stress, respectively. Linear superimposition principle is used to study the effect of mechanical, electrical and dielectric fields. Complex variable technique together with Dugdale [4] hypothesis is used to obtain the analytic closed form solution for the problems. The electromechanical non-linear effects on the structure of stresses and electrical displacements fields are investigated. Energy release rate [2-3], stress intensity factor and COD at the tip of the crack are also calculated.
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