Biaxial loading and shallow-flaw effects on crack-tip constraint and fracture-toughness
Abstract
Uniaxial tests of single-edged, notched bend (SENB) specimens with both deep- and shallow-flaws have shown elevated fracture toughness for the shallow flaws. The elevation in fracture-toughness for shallow flaws was shown to be the result of reduced constraint at the crack-tip. Biaxial loading has the potential to increase constraint at the crack-tip and thereby reduce some of the shallow-flaw, fracture-toughness elevation. Biaxial fracture-toughness tests have shown that the shallow-flaw, fracture-toughness elevation is reduced but not eliminated by biaxial loading. Dual-parameter, fracture-toughness correlations were proposed to reflect the effect of crack-tip constraint on fracture-toughness. Test results from the uniaxial and biaxial tests were analyzed using the dual-parameter technology. Discrepancies between analysis results and cleavage initiation site data from fractographic examinations indicate that the analysis models are in need of further refinement. Addition of a precleavage, ductile-tearing element to the analysis model has the potential to resolve the noted discrepancies.
- Publication:
-
Presented at the Pressure Vessel and Piping Conference
- Pub Date:
- 1994
- Bibcode:
- 1994pvp..conf...19P
- Keywords:
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- Axial Loads;
- Crack Tips;
- Defects;
- Elevation;
- Fracture Strength;
- Cleavage;
- Correlation;
- Fractography;
- Structural Mechanics