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Effective tearing modulus: a model for brittle fracture and tearing instability

Technical Report ·
OSTI ID:6022897
The objective of this study was to determine a model for the transition regime and upper shelf fracture resistance of low-strength/high-toughness structural steels. The success of the model was measured in two ways: (1) the condition for fracture specimen maximum load, intersection of applied and material effective tearing modulus curves, was satisfied for compact tension data in the transition and upper shelf fracture regimes; (2) maximum load attained by surface-flawed intermediate test vessels (ITV's) was accurately calculated by using the model and associated compact tension data. The fracture model attribute of stress-dependent plastic zone constraint was thought to be primarily responsible for its thickness insensitivity. Metallurgical fracture mode insensitivity of the model in the transition regime was thought to be primarily due to the use of a plastic zone addition to the physical crack size. Calculation of the fracture model parameters (crack driving/resistance forces and their derivatives with respect to the plastic-zone-corrected crack) was enhanced by the availability of and relationship to linear elastic fracture mechanics formulas. Ligament size criteria consistent with the fracture model were determined empirically for the compact tension specimen. Pressure vessel analyses indicated that model accuracy was acceptable provided that the average hoop stress was less than the yield stress.
Research Organization:
Knolls Atomic Power Lab., Schenectady, NY (USA)
DOE Contract Number:
AC12-76SN00052
OSTI ID:
6022897
Report Number(s):
KAPL-4190; ON: DE86008785
Country of Publication:
United States
Language:
English