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

Kirk, M.T.; Dodds, Robert H., Jr.

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https://hdl.handle.net/2142/14192 Copy

Description

Title

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

Author(s)

• Kirk, M.T.
• Dodds, Robert H., Jr.

Issue Date

1992-12

Keyword(s)

• Fracture mechanics
• finite elements
• Micromechanics
• Fracture toughness

Abstract

"This investigation examines the ability of an elastic T -stress analysis 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 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 J/Jo ). Specifically, when lBl >0.4 these analyses show that the T -MBL approximation of Jo is accurate to within 20% of a detailed finite-element analysis. As ""structural type"" configurations, i.e. shallow cracks in tension, generally have lBl > 0.4, it appears that only an elastic analysis may be needed to determine reasonably accurate Jo values for structural conditions."

Publisher

University of Illinois Engineering Experiment Station. College of Engineering. University of Illinois at Urbana-Champaign.

Series/Report Name or Number

Civil Engineering Studies SRS-575

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/14192

Sponsor(s)/Grant Number(s)

• Annapolis Detatchment, Darderock Division. Naval Surface Warfare Center Code 2814
• U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Engineering.
• Contract No. N61533-90-K-0059

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