中文摘要：

There are three types of cracks: impermeable crack, permeable crackand conducting crack, with diffbrent electric boundary conditions on faces of cracks inpiezoelectric ceramics, which poses difficulties in the analysis of piezoelectric fractureproblems. In this paper, in contrast to our previous FEM formulation, the numer-ical analysis is based on the use of exact electric boundary conditions at the crackfaces, thus the common assumption of electric impermeability in the FEM analysisis avoided. The crack behavior and elasto-electric fields near a crack tip in a PZT-5piezoelectric ceramic under mechanical, electrical and coupled mechanical-electricalloads with different electric boundary conditions on crack faces are investigated. It isfound that the dielectric medium between the crack faces will reduce the singularity ofstress and electric displacement. Furthermore, when the perufittivity of the dielectricmedium in the crack gap is of the same order as that of the piezoelectric ceramic, thecrack becomes a conducting crack, the applied electric field has no effect on the crackpropagation.

英文摘要：

There are three types of cracks: impermeable crack, permeable crack and conducting crack, with different electric boundary conditions on faces of cracks in piezoelectric ceramics, which poses difficulties in the analysis of piezoelectric fracture problems. In this paper, in contrast to our previous FEM formulation, the numerical analysis is based on the use of exact electric boundary conditions at the crack faces, thus the common assumption of electric impermeability in the FEM analysis is avoided. The crack behavior and elasto-electric fields near a crack tip in a PZT-5 piezoelectric ceramic under mechanical, electrical and coupled mechanical- electrical loads with different electric boundary conditions on crack faces are investigated. It is found that the dielectric medium between the crack faces will reduce the singularity of stress and electric displacement. Furthermore, when the permittivity of the dielectric medium in the crack gap is of the same order as that of the piezoelectric ceramic, the crack becomes a conducting crack, the applied electric field has no effect on the crack propagation.