Interaction Of A Screw Dislocation With Interfacial Edge Crack In Magneto-electro-elastic Bi-material

Magneto-electro-elastic (MEE) solid refers to a new type of composite material that possesses the coupling effects between mechanical deformation, electric field and magnetic field. Such composite often consists of a piezoelectric phase and piezomagnetic phase, and can be employed to make sensors, transducers, actuators and magneto-electric memory elements, and so on. In recent years, there is a growing interest in fundamental problems of MEE materials with defects (inclusions, holes, cracks and dislocations). The study of the interaction of dislocations with cracks is very helpful for understanding the fracture behavior of MEE material. In this thesis, based on the impermeable boundary conditions, the interaction of a screw dislocation with an interfacial edge crack in a two-phase transversely isotropic MEE medium is investigates through the use of the conformal mapping and the image-dislocation method. The main works include that: In the first part, the anti-plain magneto-electro-elastic fields by the dislocation in an infinite or half-infinite MEE medium with are derived. It's found that a screw dislocation in a MEE bi-material can induce the electric and magnetic fields due to the interaction between two phases, however, a screw dislocation in a homogenous MEE medium only produce the electric displacement and magnetic induction. Making use of the expression of the image-force, we analyze the interaction of the dislocation with the interface and the boundary. The second part of this thesis is to study the interactions of a dislocation with an interfacial edge crack in a MEE bi-material. First, the elastic and electromagnetic fields induced by the dislocation are obtained in the bi-material MEE wedge with an edge interfacial crack. And then as the special cases, the interactions of the dislocation with semi-infinite and finite edge cracks are analyzed. The numerical examples are provided to show the influences of the material properties, the wedge angle, dislocation position and the crack length on the interaction. The third part of this thesis is to investigate the interaction between a dislocation and an edge crack in MEE strip with two cases. The numerical examples illustrate the influence of the width on the image force and stress intensity factor. All results of this thesis can be degenerated to those of piezoelectric or purely elastic problems.