Multiple parallel cracks interaction problem in piezoelectric ceramics

This paper has two goals. First, we propose the 'pseudo-traction-electric displacement' method for solving the interaction problem of multiple parallel cracks in transversely isotropic piezoelectric ceramics. Second, we present a fundamental understanding for the role that the electric displacement loading plays in the interaction problem. Detailed comparisons between the results under the compound mechanical-electric loading conditions and those derived under purely mechanical loading conditions are performed. It is shown that the mechanical fracture parameters such as the stress intensity factors are no longer independent of the electric loading as they would be in single crack problems. Quite contrary, the electric displacement loading has a significant influence on the stress intensity factors, the total potential energy release rate and the mechanical strain energy release rate. This important conclusion is mainly due to the interaction effect, i.e., one of the multiple cracks releases the stresses and disturbs the electric fields near the other crack. It is also found that there are some special relative locations for the multiple parallel cracks at which the electric displacement loading has no effect on the Mode I stress intensity factor. However, the mechanical strain energy release rate has no such a property. (C) 1999 Elsevier Science Ltd. All rights reserved.