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    Studying Edge Dislocations and Wedge Disclinations in Core-Shell Nanowires by Incorporating Surface Effect

    , M.Sc. Thesis Sharif University of Technology Rezazadeh Kalehbasti, Shaghayegh (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    By considering the effect of surface/interface stresses, classical problems of the interaction between dislocations/disclinations and nanowires are addressed. In particular, two distinct problems are solved: the first one consists of an edge dislocation seated inside the shell of a core-shell nanowire and the second one investigates a wedge disclination (dipole) located inside the shell of a core-shell nanowire. The stress field of the nanowire, strain energy per unit length and the image forces acting on the defects are calculated and discussed in detail. Moreover, the results are compared with their classical counterparts. These results show that by considering the effect of... 

    Surface/Interface Effect on the Interaction of an Embedded Core-Shell Nanowire and Edge Dislocation and Generation of Misfit Dislocations in a Core-Shell Nanowire

    , M.Sc. Thesis Sharif University of Technology Enzevaee, Camelia (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    Within the surface/interface elasticity, two following problem are solved: First the elastic behavior of an edge dislocation located inside the core of a core-shell nanowire which is embedded in an infinite matrix is studied within the surface/interface elasticity theory. The corresponding boundary value problem is solved exactly by using complex potential functions. The stress field of the dislocation, image force acting on the dislocation, and the dislocation strain energy is calculated by considering the interface effect. Second, the surface/interface elasticity approach is applied to the case of a misfit core-shell nanowire system in which the misfit strain is adjusted through the... 

    Augmented RKPM Modeling of a Glide Edge Dislocation Near a Grain Boundary in the Framework of Surface/Interface Elasticity

    , M.Sc. Thesis Sharif University of Technology (Author) ; Mohammadi Shoja, Hossein (Supervisor)
    Abstract
    Traditional continuum theory of elasticity becomes remarkably inaccurate in the vicinity of singularities, and when the size eect is of concern. For example in the study of ultra-small objects and ultra-thin lms, near defects, near point of application of a concentrated load and as such, the classical solutions are not reliable. This work focuses on determination of the elastic elds of an edge dislocation near the grain boundary of two perfectly bonded nano-size crystals. It is proposed to study this problem in the context of surface/interface elasticity, and incorporate the eect of the grain boundary on the elastic elds. In contrast to the surface/interface elasticity theory, traditional... 

    Nonlocal Kernel Functions for fcc and hcp Crystals with Application to Dislocation Problems

    , Ph.D. Dissertation Sharif University of Technology Shahvaghar Asl, Silda (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    For half a century, the problem of extracting the components of the nonlocal moduli tensor of anisotropic materials has been remained unsolved. In the present work, for the first time, the solution of this problem is proposed and the components of nonlocal moduli tensor are obtained for close-packed crystals, i.e. face center cubic or hexagonal closed packed. To this end, new distinct nonlocal kernel functions which have the characteristics of discrete atomistic Green’s functions in the stress space are obtained through consideration of the nonlocal dispersion relations. Each of dispersion relations are associated with certain directions and are combined with ab initio Density Functional...