Determination of Constraint-Modified J-R Curves for Carbon Steel Storage Tanks
The fracture toughness testing of A285 carbon steel storage tank material was carried out. A series of single edge-notched bend (SENB) specimens with various constraint levels were used. The variation of crack tip constraint was achieved by changing the ratio of the initial notch length to the specimen depth. The test data show that the J-R curves are specimen-dependent, which is known as the constraint effect. A two-parameter fracture methodology is adopted to construct a constraint-modified J-R curve, which is a function of the constraint parameter, A2, while J remains the loading parameter. This additional fracture parameter is derived from a closed form solution and can be extracted from the finite element analysis for a specific crack configuration. Using this set of SENB test data, a mathematical expression for the J-R curve of the A285 carbon steel can be developed. It is shown that the predicted J-R curves match well with the SENB data over an extensive amount of crack growth. In addition, this expression of the constraint modified J-R curve is used to predict the test data of a compact tension specimen (CT), and good agreement can be achieved. To demonstrate its application in the structural integrity assessment, a generic A285 storage tank with a postulated axial flaw is used. For a flaw length of 10 percent of the tank height, the predicted J-R curve is found to be similar to that for a SENB specimen with a short notch, which is in a state of low constraint. This implies that the use of traditional J-R curve, which is typically obtained by high constraint specimens, may be overly conservative.
- Research Organization:
- Savannah River Site (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC09-96SR18500
- OSTI ID:
- 799687
- Report Number(s):
- WSRC-MS-2002-00143
- Country of Publication:
- United States
- Language:
- English
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