Approximate Techniques for Predicting Size Effects on Cleavage Fracture Toughness (Jc)

Abstract

This investigation examines the ability of an elastic T-stress coupled with a modified boundary layer (MBL) solution to predict stresses ahead of a crack tip in a variety of planar geometries. The approximate stresses are used as input to estimate the effective driving force for cleavage fracture (JO) using the micromechanically based approached introduced by Dodds and Anderson. Finite element analyses for a wide variety of planar cracked geometries are conducted which have elastic biaxiality parameters (B) ranging from -0.99 (very low constraint) to +2.96 (very high constraint). The magnitude and sign of B indicate the rate at which crack-tip constraint changes with increasing applied load. All results pertain to a moderately strain hardening material (strain hardening exponent(n) of 10). These analyses suggest that B is an effective indicator of both the accuracy of T-MBL estimates of Jo and of applicability limits on evolving fracture analysis methodologies (i.e. T-MBL, J-Q, and JIJO).. .. Elastic-plastic fracture mechanics, Size effects, Finite element analysis modified boundary layer, T-stress, Jssy, Jo' Q, Structural integrity assessment.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 1993
Accession Number
ADA261591

Entities

People

  • Mark T. Kirk
  • Robert H. Dodds Jr.

Organizations

  • University of Illinois Urbana–Champaign

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Boundaries
  • Boundary Layer
  • Crack Tips
  • Failure Mode And Effect Analysis
  • Finite Element Analysis
  • Fracture (Mechanics)
  • Geometry
  • Hardening
  • Materials
  • Mechanics
  • Physics
  • Plastic Flow
  • Strain Hardening
  • Stress Strain Relations
  • Stresses
  • Structural Integrity
  • Three Dimensional

Readers

  • Materials Science (Mechanical Engineering).