Antiplane mechanical and inplane electric time-dependent load applied to two coplanar cracks in piezoelectric ceramic material

This work is concerned with the dynamic response of two coplanar cracks in a piezoelectric ceramic under antiplane mechanical and inplane electric tim e-dependent load. The cracks are assumed to act either as an insulator or a s a conductor, Laplace and Fourier transforms are used to reduce the mixed boundary value problems to Cauchy-type singular integral equations in Lapla ce transform domain. A numerical Laplace inversion algorithm is used to det ermine the dynamic stress and electric displacement factors that depend on time and geometry. A normalized equivalent parameter describing the ratio o f the equivalent magnitude of electric load to that of mechanical load is i ntroduced in the numerical computation of the dynamic stress intensity fact or (DSIF) which has a similar trend as that for the pure elastic material. The results show that the dynamic electric field will impede or enhance cra ck propagation in a piezoelectric ceramic material at different stages of t he dynamic electromechanical load. Moreover, the electromechanical response is greatly affected by the ratio of the crack length to the ligament betwe en the cracks. The stress and electric displacement intensity factor can be combined by the energy density factor or function to address the fracture of piezoelectric materials under the combined influence of electromechanica l loading. (C) 2000 Elsevier Science Ltd. All rights reserved.