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Since the classical continuum theory fails to deal with the problems associated with defects, stress concentrators, and relevant deformation phenomena in solids, alternative approaches that can detect the atomistic nature of materials' fracture are required. The deficiency of the capture the size effect which yields delusively high values for some components of the stress field right on the edge of the stress concentrators, and its weakness in describing the complex interaction between small inhomogeneities, cracks and the like when they are only a few nanometers apart, are among some of the disadvantages of the classical approach. In recent years, however, atomistic methods are emerging to... 

Classical continuum mechanics fails to give an accurate solution near the crack tip, moreover, it implies that a solid is able to sustain an infinite stress at the Griffith-Inglis crack tips. Among other critical issues is the inability of classical approach to sense the size effect. For these reasons, for more in-depth understanding and accurate behavioral predictions, it is essential to develop some atomistic methods which properly accounts, not only for the structure but also the long and short range atomic interactions effectively. In this work the interaction of coated inhomogeneity and crack under polynomial loading is simulated by using the many body Rafii-Tabar and Sutton potential... 

Nanocomposites are widely used due to unique properties such as low density and high strength in many industries such as electronics, telecommunications, aerospaces, Petrochemicals and shipbuildings. Meanwhile, due to the importance of economic issues, polymer based nanocomposites are the most used type of nanocomposites. The purpose of this thesis is studing the structural defects of graphene-reinforced nanocomposite polymers on the mechanical properties of these materials. Defects created in nanocomposites can be divided into two categories after construction. The first category is the defects that are created in the graphene structure when it is synthsis, and the second happen at the...