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|Title:||NUMERICAL SIMULATION OF 3-D CRACKS USING X-FEM|
|Authors:||Yadav, Saurabh Kumar|
|Keywords:||MECHANICAL INDUSTRIAL ENGINEERING;3-D CRACKS;X-FEM;STRESS INTENSITY FACTORS|
|Abstract:||The modeling of fracture and failure is quite useful for the life prediction of critical components such as aircraft, automobiles and nuclear pressure vessels. Cracks, as a result of manufacturing defects or localized damage, may extend until brittle fracture occurs. The aim of this dissertation is to develop algorithms which can effectively simulate the fatigue cracks growth. The modeling of cracks growth in 3-D poses essential difficulties as one has to deal with crack surface and crack front which may be concave or convex. The accurate modeling of such 3-D cracks growth in finite bodies remains a challenging problem for computational fracture mechanics. Therefore, in this work, an ideal approach known as extended finite element method (XFEM) has been used for the modeling of 3-D cracks in finite domains. According to this approach, a cracked body/component is initially meshed using 3-D elements without the presence of a crack. The presence of a 3-D crack is ensured by enrichment functions. The elements, which are completely cut by the crack surface, are enriched with Heaviside jump function, and elements, which are partially cut by the crack front, are enriched with a branch function. The crack propagation is modeled by successive line segments, which are determined by the stress intensity factors (SIFs) obtained after linear elastic analysis. The direction of these increments is determined from the maximum principle stress criterion. Some planer and non-planar cracks are taken for the simulation of crack growth problems. Few 3-D model crack problems such as edge and penny cracks in finite domain are solved by harmonic XFEM. Shifted enrichment is used in Harmonic XFEM to capture crack tip singularity. In this enrichment approach, only one enrichment function is used instead of using two types of enrichment functions. Numerical harmonic enrichment function is derived from solution of the Laplace domain. Few model problems are solved by developed algorithm, and the results obtained from this algorithm are compared with those available in literature.|
|Research Supervisor/ Guide:||Singh, I. V.|
|Appears in Collections:||MASTERS' DISSERTATIONS (MIED)|
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