A screw dislocation interacting with a coated fiber

Abstract

A close-form analytical solution is obtained for the stress field due to a screw dislocation near a coated fiber inhomogeneity in isotropic material. The forces on dislocations are derived. The equilibrium positions of the dislocation are discussed in detail for various material constants’ combinations. It is found that when the coating layer is thick, the elastic property of the fiber (inclusion) has no significant influence on the force of the dislocation, therefore the equilibrium and stability of the dislocation can be obtained similarly from the two-phase model adopted by Dunders (1967. Recent Advances in Engineering Science 2, 223–233). On the other hand when the coating layer is thin, if both the fiber and the coating layer are “softer” (i.e., have lower modulus) than the matrix, the dislocation is always attracted by the fiber, and if both the fiber and the coating are “harder” (i.e., have higher modulus) than the matrix, the dislocation is always repelled by the fiber. As a result, there are no equilibrium positions under these two conditions. While if the fiber is harder and the coating is softer than the matrix, there is at least one unstable equilibrium position near the coating–matrix interface, if the fiber is softer and the coating is harder than the matrix, there is at least one stable equilibrium position near the coating–matrix interface.