Using the extended version of Eshelby-Stroh's formulation and the method of analytical continuation, the problems of interface cracks are reduced to a Hilbert problem of vector form. A general explicit closed form solution for piezothermoelastic interface crack problem is then obtained, the whole field solutions of temperature, heat flux, displacements, electric field, stress and electric induction are given, the explicit expressions for the crack opening displacements and electric potential are also provided. A solution is obtained for the interaction problem between the interface cracks and a point heat source.

In this paper, the concept of energy density factor S for piezoelectric materials is presented. In addition to the mechanical energy the electrical energy is included as well. The direction of crack initiation is assumed to occur when Smin reaches a critical value Scr that can be used as an intrinsic materials parameter and is independent of the crack geometry and loading. The result agrees with empirical evidence qualitatively and explains rationally the effect of applied electric field on fracture strength: positive electric fields decrease the apparent fracture toughness of piezoelectric materials while negative electric fields increase it.

After the Hamilton principle for thermo-mechanical electric coupling problem is derived, the third-order shear deformation theory is extended to encompass piezothermoelastic laminated plates. Based on the velocity feedback control, a model for the active vibration control of laminated plates with piezothermoelastic sensor: actuator is established. An analytical solution is obtained for the case of general forces acting on a simply supported piezothermoelastic laminated plate. Numerical results are presented. The factors that influence the controlled responses of the plate are examined.

The interface crack problems of a laminated piezoelectric plate under a state of generalized plane deformation have been studied within the anisotropic theory. The method of Fourier transforms and the stiffness matrix formulation have been employed and the problem has been reduced to the solution of a system of singular integral equations. The stress and induction intensity factors have been provided, and have been calculated numerically and displayed graphically.

This work is concerned with the analytical characterization of the electromechanical nonlinear effects on the fields surrounding the tip of an interface crack between ferroelectric-plastic bimaterials. A strip electric saturation and mechanical yielding model is developed for a mode III interfacial crack with electrical polarization reaching a saturation limit and shear stress reaching a yield stress along a line segment in front of the crack. The electrical saturation zone and mechanical yielding zone may have dierent length scales depending on loading conditions. This model may be considered as a generalization of the classical Dugdale model for plastic yielding near cracks in homogenous materials. The results reveal insight into the structure of stress and electric displacement fields for different load conditions. The energy release rate and COD dIII are also obtained, which indicates the possibility of fracture criterion based on the COD dIII.