Peridynamic modelling of internal features and interfaces for material toughening
Rahimi, Mohammad Naqib (2020) Peridynamic modelling of internal features and interfaces for material toughening. [Thesis]
Metals and ceramics are the two widely used materials in naval, aerospace, and structural engineering due to their high stiffness/weight ratio and design flexibility. However, their vulnerability to the occurrence of micro/macro cracks limits their potential and usage for the critical engineering applications. One way to improve the capabilities of metals and ceramics against crack occurrences is the implantation of the local weak zones into the material. Nevertheless, numerical analysis of such domains become quite challenging due to the simultaneous interactions of multiple interfaces, discontinuities, and phase changes. This study aims to systematically analyze the effects of different local weak zones on the behavior of the crack and the global toughness of homogeneous and graded materials. The realms of this thesis are assessed in two articles with an improved peridynamic formulation for precise modeling of interfaces. In the first paper, traditional peridynamic formulation is used to simulate the effects of the shape and locations of stop-holes on crack dynamics in homogeneous materials. Various combinations of stop-holes are analyzed under tensile and shear loadings while comparing their toughening effects. In the second paper, an improved formulation of peridynamic is proposed for graded composites by considering the interface and multiscale effects, through introducing the dominancy rate parameter. Overall, this study provides a unique contribution to the existing state of the art in terms of proposing a novel peridynamic methodology which can handle modelling of sharp transitions in material properties as well as suggesting numerically validated new toughening configurations for different materials.
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