Isoparametric Elements as Singular Elements for Crack Problems.

Abstract

The quadratic isoparametric elements, which embody the inverse square root singularity, are used for calculating the stress intensity factors at tips of cracks. The elements used are the quadratic quadrilateral (8-node), quadratic triangular (6-node) and three-dimensional quadratic brick (20-node) elements. Singularity elements are obtained in a simple manner by placing the mid-side nodes at quarter points in the vicinity of the crack tip or an edge. These elements are implemented in NASTRAN as dummy (user) elements. The method eliminates the use of special crack tip elements and in addition, these elements satisfy the constant strain and rigid body modes required for convergence. The stability of two-dimensional elements is also investigated. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1977
Accession Number
ADA052583

Entities

People

  • M. A. Hussain
  • W. E. Lorensen

Organizations

  • United States Army Armament Research, Development and Engineering Center

Tags

Communities of Interest

  • C4I
  • Weapons Technologies

DTIC Thesaurus Topics

  • Accuracy
  • Cartesian Coordinates
  • Computational Fluid Dynamics
  • Crack Tips
  • Demographic Cohorts
  • Equations
  • Gaussian Quadrature
  • Geometry
  • Grids
  • Intensity
  • Materials
  • Mechanics
  • Sequences
  • Stress Intensity Factors
  • Stresses
  • Three Dimensional
  • Two Dimensional

Readers

  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)
  • Materials Science (Mechanical Engineering).