Linear elastic fracture simulation directly from CAD: 2D NURBS-based implementation and role of tip enrichment

in International Journal of Fracture (2016)

3D fatigue fracture modeling by isogeometric boundary element methods

Scientific Conference (2016, April 01)

C++ implementation of 2D PHT splines

Learning material (2016)

Isogeometric boundary element methods for three dimensional fatigue crack growth

Report (2015)

The isogeometric boundary element method (IGABEM) based on NURBS is adopted to model fracture problem in 3D. The NURBS basis functions are used in both crack representation and physical quantity ... [more ▼]

The isogeometric boundary element method (IGABEM) based on NURBS is adopted to model fracture problem in 3D. The NURBS basis functions are used in both crack representation and physical quantity approximation. A stable quadrature scheme for singular integration is proposed to enhance the robustness of the method in dealing with highly distorted element. The convergence study in crack opening displacement is performed for penny-shaped crack and elliptical crack. Two ways to extract stress intensity factors (SIFs), the contour $M$ integral and virtual crack closure integral, are implemented based on the framework of dual integral equations. An algorithm is outlined and validated to be stable for fatigue crack growth, thanks to the smoothness not only in crack geometry but also in stress/SIFs solution brought by IGABEM. [less ▲]

An isogeometric boundary element method for fracture modeling

Presentation (2015, May)

Crack growth analysis by a NURBS-based isogeometric boundary element metyhod

Presentation (2014, July)

Damage tolerance assessment directly from CAD: (extended) isogeometric boundary element methods

Scientific Conference (2014, June)

A Two-Dimensional Isogeometric Boundary Element Method For Linear Elastic Fracture

Scientific Conference (2014, January)

Damage tolerance assessment directly from CAD: (extended) isogeometric boundary element methods (XIGABEM)

Scientific Conference (2014)

smooth nodal stress in the XFEM for crack propagation simulations

Scientific Conference (2013, September)

In this paper, we present a method to achive smooth nodal stresses in the XFEM without post-processing. This method was developed by borrowing ideas from ``twice interpolating approximations'' (TFEM) [1 ... [more ▼]

In this paper, we present a method to achive smooth nodal stresses in the XFEM without post-processing. This method was developed by borrowing ideas from ``twice interpolating approximations'' (TFEM) [1]. The salient feature of the method is to introduce an ``average'' gradient into the construction of the approximation, resulting in improved solution accuracy, both in the vicinity of the crack tip and in the far field. Due to the high order polynomial basis provided by the interpolants, the new approximation enhances the smoothness of the solution without requiring an increased number of degrees of freedom. This is particularly advantageous for low-order elements and in fracture mechanics, where smooth stresses are important for certain crack propagation criteria, e.g. based on maximum principal stresses. Since the new approach adopts the same mesh discretization, i.e. simplex meshes, it can be easily extended into various problems and is easily implemented. We discuss the increase in the bandwidth which is the major drawback of the present method and can be somewhat alleviated by using an element-by-element solution strategy. Numerical tests show that the new method is as robust as XFEM, considering precision, model size and post-processing time. By comparing in detail the behaviour of the method on crack propagation examples, we can conclude that for two-dimensional problems, the proposed method tends to be an efficient alternative to the classical XFEM [2][3] especially when local, stress-based propagation criteria are used. [less ▲]