J-A
2 Characterization of Crack-Tip Fields: Extent of J-A
2 Dominance and Size Requirements |
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Authors: | Yuh J Chao XK Zhu |
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Affiliation: | (1) Department of Mechanical Engineering, University of, South Carolina, Columbia, SC, 29208, U.S.A |
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Abstract: | The requirements for J-dominance, limits of the single-parameter criterion to characterize the fracture of engineering structures,
and two-parameter fracture analyses are first reviewed. Through comparison, it is argued that the two-parameter fracture methodology
based on the J-A
2 theory is a reasonable extension of the single parameter (J-integral) fracture methodology. Consequently the extent of J-A
2 dominance in various specimens under either tension or bending is investigated in detail in this paper. Using the J
2 flow theory of plasticity and within the small-strain framework, full field finite element solutions are obtained for both
deep and shallow crack geometries of single edge notch bar under pure bending SEN(B)] and central cracked panel in uniform
tension CC(T)]. These crack-tip stresses are compared with those in the HRR singularity fields and the J-A
2 asymptotic fields at the same level of applied J. The comparison indicates that the size R of the region dominated by the
J-A
2 field is much larger than that of the HRR field around the crack tip. Except for deeply-cracked SEN(B) in low hardening material
(n=10) under fully plastic conditions, the numerical results near the crack tip in both SEN(B) and CC(T) match very well with
the J-A
2 asymptotic solutions in the area of interest 1<r/(J/σ0)<5 from well-contained to large scale plasticity. The implications of these results on the minimal specimen size requirements
essential to a two-parameter fracture criterion based on the J-A
2 asymptotic solution are then discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | Size requirement J-A 2 dominance crack-tip field fracture criterion elastic-plastic material |
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