Conducting cracks in a piezoelectric ceramic of limited electrical polarization

Recent studies show that dielectric nonlinearity (especially the electrical polarization saturation) plays an essential role in the description of cra ck tip behavior of ferroelectric/piezoelectric ceramics. This paper studies conducting cracks in a poled ferroelectric of limited electrical polarizat ion based on a strip-saturation model of the Dugdale-type. The resulting mi xed boundary value problem is analysed and complete solution or exact near tip held is obtained for conducting cracks parallel or perpendicular to the poling axis. It is found that pure electric-field loading applied parallel to the poling axis does not induce ally stress intensity factor at conduct ing cracks. This conclusion distinguishes conducting cracks in a poled ferr oelectric from insulating cracks for which the strip-saturation model predi cts an electrically induced stress intensity factor. Due to its practical i mportance, the conducting crack parallel to the poling axis is discussed in more detail. The results indicate that the driving force predicted by the strip-saturation model is lower than that given by the linear piezoelectric model for a conducting crack parallel to the poling axis. (C) 1999 Elsevie r Science Ltd. All rights reserved.