Effect of Crack-tip Region Constraint on Fracture in the Ductile-to-brittle Transition
Effect of Crack-tip Region Constraint on Fracture in the Ductile-to-brittle Transition

Author: Ted L. Anderson

Publisher:

Published: 1984

Total Pages: 199

ISBN-13:

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The effect of geometry on fracture toughness of steel in the ductile-to-brittle transition region has been studied. The critical crack-tip opening displacement (CTOD) and the critical J-integral have been measured as a function of temperature for ten fracture specimen configurations of ABS grade EH36 steel. A technique was developed to experimentally measure crack-tip constraint. Constraint decreased with crack blunting. This relaxation in constraint was modeled by a simple spring analog. The model was used to predict ductile-to-brittle transition curves for hypothetical structures. Some of the applications and limitations of the model are discussed.

3-D Constraint Effects on Models for Transferability of Cleavage Fracture Toughness
3-D Constraint Effects on Models for Transferability of Cleavage Fracture Toughness

Author: RH. Dodds

Publisher:

Published: 1997

Total Pages: 19

ISBN-13:

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Since the late 1980s there has been renewed interest and progress in understanding the effects of constraint on transgranular cleavage in ferritic steels. Research efforts to characterize the complex interaction of crack tip separation processes with geometry, loading mode and material flow properties proceed along essentially two major lines of investigation: (1) multi-parameter descriptions of stationary crack-tip fields under large-scale yielding conditions, and (2) rational micromechanics models for the description of cleavage fracture which also reflect the observed scatter in the ductile-to-brittle transition (DBT) region. This article reviews the essential features of a specific example representing each approach: the J-Q extension to correlative fracture mechanics and a local approach based on the Weibull stress. Discussions focus on the growing body of 3-D numerical solutions for common fracture specimens which, in certain cases, prove significantly different from long-established plane-strain results.