Electromechanical response of cracks in piezoelectric materials under combined mechanical and electrical loadings

An experimental and analytical investigation of the electromechanical response of cracks in piezoelectric ceramics subject to combined mechanical and electrical loading is performed. The cracks are created and propagated in piezoelectric lead zirconium titanate (PZT) material under simultaneous mechanical and electrical loads using the Vickers indentation technique. The results have demonstrated that electrical loads can inhibit or enhance crack propagation in piezoelectric materials. Cracks introduced by indentation are observed to propagate less under a positive applied electric field in which the polarity of the field is the same as that for poling whereas the crack propagation is enhanced under a negative applied electric field. Such an effect is observed to be more profound with increasing electric field strength and decreasing mechanical loading. A finite element analysis is performed to model the electromechanical response of cracks in PZT subjected to simultaneous applications of mechanical and electrical loading. It is shown that the stress intensity factor at the crack tip is increased for a negative applied electric field, whereas it is decreased for a positive applied electric field.