Interaction Between Dislocation And Several Typical Microscopic Stractures In Piezoelectrical Medium

The interaction of dislocation and microscopic stracture a greatly significant subject in the fields of solid mechanics and materials science. The elastic and electroelastic interaction effects between screw dislocations and several typical microscopic stractures in anisotropic materials are investigated in this paper. The purpose of this paper is investigating the dynamic stress intensity factor of an uniform moving interfacial crack in two dissimilar piezoelectric media arising from generalized screw dislocation; cracking characteristics of screw mode dislocations near a lip-like mode crack and the problem of interaction between a screw dislocation dipole and a circular inhomogeneity containing interfacial rigid lines.Using Riemann-Schwarz's symmetry principle of complex functions, the above problems are transformed into Riemann-Hilbert boundary problems. By combining the analysis of singularity of complex functions, generalized Liouville's theorem and Cauchy model integral, the explicit solutions to the complex variable functions of above problems are provided. With the aid of the Peach-Koehler formula, the image forces on dislocation are obtained respectively. The dependence of image force on materials'properties and imperfect interface parameters are calculated, plotted and discussed.As a result, in the problem of an uniform moving iterfacial crack in two dissimilar piezoelectric media arising from generalized screw dislocation,analysis and discussion show that both of Shielding effect and stress intensity factor about electric displacement decrease with normalized time tend to zero and the larger velocity of moving crack. In the problem of the interaction of dislocation and a lip-like mode crack show that shielding effect generated by screw dislocation near a lip-like mode crack decreases with the increment of the distance between screw dislocation and crack tip. Larger height of the crack leads to the shielding effect waning.Meanwhile, between a crew dislocation dipole and a circular inhomogeneity containing interfacial rigid lines, the stress intensity factors at the rigid line tip, the image force and image torque acting on the center of screw dislocation dipole are calculated. The results show that, screw dislocation dipole may shield the rigid line tip and the latter may repel the dislocation dipole. In addition, the influence of the dipole arm orientation on the equilibrium of the dipole is significant.The provided results can not only offer a scientific basis for the design of composite structures but also provide basic solutions to further investigation on the strength and toughness of structures. The present solutions contain a number of previously known results which can be shown to be special cases.