Generalized Linear Elastic Fracture Model for Advanced Materials.

Abstract

The branched crack problem for both an isotropic and anisotropic material is solved using the method of dislocations, and the stress intensity factors and T-stress in front of the branched crack are evaluated numerically. The T-stress based fracture criteria, developed by Cotterell and Rice for a flat crack, is modified by incorporating an experimentally determined critical T-stress value (Tcrit). Based on this Tcrit, a modified T-stress based fracture criteria is proposed. This criteria is applied to the branched crack and the direction of growth of the branched crack is discussed by comparing the theoretically evaluated T-stress values with some available experimentally determined Tcrit values. The solution for the branched crack problem is obtained in terms of a singular integral equation which is solved using three different numerical schemes, the merits of which are discussed. The nature of the stress singularity at the reentrant wedge corner of the branched crack is analyzed and is verified for the isotropic case. It is shown that the T-stress and the stress intensity factors are insensitive to the order of the singularity assumed at the reentrant wedge comer of the branched crack in either an isotropic or anisotropic material. The T-stress for the isotropic case is obtained in terms of applied load, kink length and kink angle. For the anisotropic case the T-stress also depends on the relative stiffness properties of the fibre and matrix. For a uniaxial loading case, by applying the modified T-stress based criteria to the branched crack, it is demonstrated that for a short kink length the kink will turn from its initial direction and realign with the main crack. If the loading is biaxial then the kink growth direction depends strongly on applied transverse stress. (MM)

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Document Details

Document Type
Technical Report
Publication Date
Sep 30, 1995
Accession Number
ADA306131

Entities

People

  • Alex S. Selvarathinam
  • J. Goree

Organizations

  • Clemson University

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Axial Loads
  • Complex Variables
  • Composite Materials
  • Conformal Mapping
  • Contour Integrals
  • Equations
  • Ferrium
  • Geometry
  • Integral Equations
  • Integrals
  • Literature Surveys
  • Materials
  • Mathematics
  • Mechanical Engineering
  • Mechanics
  • Numerical Analysis
  • Two Dimensional

Readers

  • Materials Science (Mechanical Engineering).
  • Structural Dynamics.