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Isogeometric boundary element methods for linear elastic fracture mechanics

Peng, Xuan 2016. Isogeometric boundary element methods for linear elastic fracture mechanics. PhD Thesis, Cardiff University.
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Abstract

We develop in this work a procedure for obtaining the fatigue life of complex structures directly from Computer-Aided Design (CAD) data, without any mesh generation or regeneration as the cracks evolve. The method relies on a standard isogeometric boundary element method (IGABEM) where the same basis functions are used to both describe the geometry of the component and approximate the displacement and traction fields. The contributions of this work include: (1) Dual boundary integral equations have been applied to model 2D/3D fracture problems in the framework of IGA and that such simulations require no meshing or remeshing in the conventional sense; (2) Graded knot insertion and partition of unity enrichment have been used to capture the stress singularity around the crack tip. The contour-integral based methods and the virtual crack closure integral method are adopted to extract stress intensity factors in the framework of IGABEM; (3) Modifications on the singularity subtraction technique for (hyper-)singular integration are proposed to enhance the quadrature on distorted elements which commonly arise in IGA; (4)ANURBS-based geometry modification algorithm is developed to simulate fatigue crack growth in 2D/3D. smooth crack trajectory and crack front are obtained; (5) An implementation on trimmed NURBS is realized based on a localized double mapping method to perform the quadrature on trimmed elements. A phantom element method is subsequently proposed to model the surface crack (breaking crack) problem and the displacement discontinuity can be introduced without any reparametrization on the original patch.

Item Type: Thesis (PhD)
Date Type: Publication
Status: Unpublished
Schools: Engineering
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
T Technology > TJ Mechanical engineering and machinery
Uncontrolled Keywords: Isogeometric Analysis; NURBS; Linear elastic fracture; Boundary element method; Crack growth; Fracture simulations directly from CAD.
Date of First Compliant Deposit: 14 July 2016
Last Modified: 25 Jun 2017 05:54
URI: http://orca.cf.ac.uk/id/eprint/92543

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