A method to compute mixed-mode stress intensity factors for nonplanar cracks in three dimensions

Benjamin E. Grossman-Ponemon, Leon M. Keer, Adrian J. Lew*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Methods to compute the stress intensity factors along a three-dimensional (3D) crack front often display a tenuous rate of convergence under mesh refinement or, worse, do not converge, particularly when applied on unstructured meshes. In this work, we propose an alternative formulation of the interaction integral functional and a method to compute stress intensity factors along the crack front which can be shown to converge. The novelty of our method is the decoupling of the two discretizations: the bulk mesh for the finite element solution and the mesh along the crack front for the numerical stress intensity factors, and hence we term it the multiple mesh interaction integral (MMII) method. Through analysis of the convergence of the functional and method, we find scalings of these two mesh sizes to guarantee convergence of the computed stress intensity factors in a variety of norms, including maximum pointwise error and total variation. We demonstrate the MMII on four examples: a semiinfinite straight crack with the asymptotic displacement fields, the same geometry with a nonuniform stress intensity factor along the crack front, a spherical cap crack in a cylinder under tension, and the elliptical crack under far-field tension and shear.

Original languageEnglish (US)
Pages (from-to)4292-4328
Number of pages37
JournalInternational Journal for Numerical Methods in Engineering
Volume121
Issue number19
DOIs
StatePublished - Oct 15 2020

Keywords

  • finite element methods
  • fracture
  • singularities

ASJC Scopus subject areas

  • Numerical Analysis
  • Engineering(all)
  • Applied Mathematics

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