Study On Interaction Between Dislocation And Piezoelectric Inclusion And Misfit Dislocation Nucleation

In the present paper, taking the piezoelectric materials or magneto-electro-elastic materials with defects as research object,the interaction betweengeneralized screw dislocation and nano-sized circle inhomogeneties with interfaceeffect, circle inhomogeneties with imperfect interface and nano-sized film hasbeen studied. The previous investigation involving the interaction betweendislocations and inhomogeneities is restricted to the dimension of micrometerrange or large than it and the perfect bonding along the interface. When thecross-section of the inhomogeneity has the dimension in nanometer scale orimperfect bonding along the interface, due to the intensive interface effect andsize effect and imperfect interface parameter, the interaction effect betweendislocations and inhomogeneities will be changed markedly. By the applied ofgeneralized complex variable method which is developed by the author andcollaborators, a series of close solutions are obtained. Meanwhile, in the presentpaper, the author introduced interface effect and imperfect interface model in thepiezoelectric materials and magnetoelectroelastic solid respectively.Firstly, the electroelastic interaction between a piezoelectric generalizeddislocation and nanoscale circle inhomogeneities with interface effect isinvestigated. The analytical expressions of image force, stress field and electricdisplacement field of the matrix and the inhomogeneities had been obtained, whenthe generalized piezoelectric dislocation located in the matrix. The influence ofproperties of materials and interface effect on the image force is discussed. Theresults show that the generalized piezoelectric dislocation which located in thematrix can be repelled by soft nano-scaled inhomogeneities with interface effectwhen the interface effect is considered. In addition, the positive interface effectcan repel the generalized screw piezoelectric dislocation which located in thematrix.Secondly, misfit dislocation nucleation condition on the interface betweennanoscale film and matrix has been studied. Two problems are studied:1. Misfitscrew dislocation nucleation on the interface between nanoscale film whichconnected to the inner surface of nanoscale hole and matrix,2. Misfit screwdislocation nucleation on the interface between nanoscale film which connected to the outter surface of nanowire and nanowire matrix. The critical condition ofmisfit dislocation nucleation on the interface between film and matrix has beenderived, either in the matrix or the film region. The influence of materialproperties and misfit strain on the critical thickness value which generate misfitdislocation is studied. The results show that, if the material properties ratio ofmatrix and film reach to a certain value, the misfit dislocation can not be nucleated;if the misfit strain less than critical value, the misfit dislocation can not benucleated yet.Lastly, the magnetoelectroelastic coupling interaction between a generalizedscrew dislocation and a circular inhomogeneity with an imperfect interface intransversely isotropic magnetoelectroelastic solids solid under remote anti-planeshear stresses and in-plane magnetoelectric loads is investigated. The generalizedscrew dislocation may be located either outside or inside the inhomogeneity and issubjected to a point force, a point charge and a point electric current at the core.By means of a complex-variable method, the analytic solutions ofmagnetoelectroelastic fields are obtained. With the aid of the generalizedPeach-Koehler formula, the explicit expressions of image forces exerted on thepiezoelectric screw dislocations are derived. The influence of the interfaceimperfection on the magnetoelectroelastic fields inside the inhomogeneity isstudied. The image force acting on the generalized screw dislocation near theimperfect interface is also discussed for variable parameters (interfaceimperfection, material magnetoelectroelastic mismatch, and dislocation position).