SEDL / STP / STP1389-EB / STP14800S

Application of the Two-Parameter J-A² Description to Ductile Crack Growth

Chao, YJ
Department of Mechanical Engineering, University of South Carolina, Columbia, SC

Zhu, XK
Department of Mechanical Engineering, University of South Carolina, Columbia, SC

Lam, P-S
Westinghouse Savannah River Company, Aiken, SC

Louthan, MR
Westinghouse Savannah River Company, Aiken, SC

Iyer, NC
Westinghouse Savannah River Company, Aiken, SC

Pages: 18    Published: Jan 2000

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Abstract

Typical ASTM fracture testing determines the J-integral resistance (J-R) curve or fracture toughness (JIC) based on specimens with high-constraint geometry such as those specified in ASTM E 1737-96. A three-term asymptotic solution with two parameters, J and A² (a constraint parameter), has been developed for characterizing the constraint effect of various geometries. The present paper extends the J-A² characterization of a stationary crack tip to the regime of stable crack growth. Similar to the concept of J-controlled crack growth, theJ-A² description can be approximately used to characterize ductile crack growth under certain amount of crack extension. The region ofJ-A²controlled crack growth is much larger than that controlled by theJ-integral alone. From the relationships between A² and the test data, JIC, and tearing modulus, TR, the coefficients used to define a J-R curve can be determined. for non-standard specimens or actual structures, once the constraint parameter A² is determined, the J-R curves appropriate for these geometries can then be obtained. A procedure of transferring J-R curves determined from the standard ASTM procedure to non-standard specimens or flawed structures is outlined in the paper.