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Title:Approximate Techniques for Predicting Size Effects on the Cleavage Fracture Toughness (Jc)
Author(s):Kirk, M.T.; Dodds, Robert H., Jr.
Subject(s):Fracture mechanics
finite elements
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.
Issue Date:1992-12
Publisher:University of Illinois Engineering Experiment Station. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Civil Engineering Studies SRS-575
Genre:Technical Report
Sponsor: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
Date Available in IDEALS:2009-11-09
Identifier in Online Catalog:3536684

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