Interfacial sliding in a bi-layered multiferroic ceramics: Localized sliding-prevention/promotion based mechanism of intra-layer fracture

Sliding is a typical failure mode of composite interfaces. According to traditional theory, interfacial sliding can be represented by the linear shear-spring model (LSSM). Although the required driving interfacial shear stress has been characterized by LSSM, the relation between interfacial normal stress and sliding is not yet reflected by it. The present paper proposes an interfacial sliding-prevention/promotion model to consider the effect of interfacial normal stress on interfacial sliding. As an example of application, the intra-layer fracture problem is analyzed on a bi-layered multiferroic ceramics. Green’s functions are derived to construct the Cauchy singular integral equations, which are further numerically solved to get mechanical strain energy release rate (MSERR) and interfacial normal stress. Parametric studies yield a new finding that non-zero normal stress may be produced in local interfacial regions by intra-layer cracks under pure in-plane shear. Local positive normal stress gives rise to local sliding-promotion effect, while local negative normal stress leads to local sliding-prevention effect. The interfacial shear imperfection and local sliding-prevention/promotion constitute the mechanisms for the variation of MSERRs of the two intra-layer cracks.