Studying the Interaction Between Dislocation Sandin Homogeneities in Nano-Scale, by Incorporating Surface Effect<br/>

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Studying the Interaction Between Dislocation Sandin Homogeneities in Nano-Scale, by Incorporating Surface Effect

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 42545 (09)
University: Sharif University of Technology
Department: Civil Engineering
Advisor(s): Mohammadi Shodja, Hossein
Abstract:
By considering the effect of surface/interface stress, classical problems of the interaction between dislocations and inhomogeneities are addressed. Especifically two distinct problems are solved, the first one is consisted of an edge dislocation located near an elliptical nano-inhomogeneity and the second one hasa screw dislocation laid in the core-shell nanowire. The stress field as well as the image force on the dislocation are calculated and discussed in detail. Results show that by decreasing the dimension of the problem to nano-scale, the differences between classical elasticity and surface approachincrease rapidly. By considering the effect of the surface/interface stress, new equilibrium positions will be observed. We can see that surface/interface with positive (negative) shear modulus will repell (attract) the screw dislocation. All of the mentioned differences either in the stress or in the image force are considerable for dimensions below 20 nm
Keywords:
Surface Effect ; Nanowire ; Nanomaterials ; Stepped Substrate ; Nano Sized ; Elliptical Inhomogeneity