Abstract
The matching of crack-tip constraint is a key issue for the developing of accurately structure integrity assessment method. For more and more non-standard specimens with different constraint states were used in the scientific research, it is especially significant to establish the matching of constraint between standard specimen and non-standard specimen. In this article, the single edge-notched bend specimens with various constraint states were selected, and the unified constraint parameter Ap under different J-integrals was calculated by finite element analysis. And then, based on the J-Ap curves, the matching of crack-tip constraint between different specimens was studied, and the matching specimens were given. In order to confirm the reliability of results, some experiments focused on the matching specimens were performed. The experiment results showed that the matching is valid. For the fracture properties of matching specimens are matching also, it is significant to the accurate assessment of structural integrity.
Highlights
Constraint is the resistance of a structure against plastic deformation.[1]
In the current integrity assessment methods based on the macro-fracture mechanics, standard specimen for the fracture toughness testing has severely size requirement to make sure a high constraint state.[3,4,5,6,7,8]
For the constraint is the resistance of structure against plastic deformation,[1] the minimum Ap means the highest constraint state
Summary
Constraint is the resistance of a structure against plastic deformation.[1] It can be divided into in-plane constraint and out-of-plane constraint. The in-plane constraint is affected by the length of un-cracked ligament, while the out-of-plane constraint is affected by the specimen thickness. In the current integrity assessment methods based on the macro-fracture mechanics, standard specimen for the fracture toughness testing has severely size requirement to make sure a high constraint state.[3,4,5,6,7,8] For the flawed structure involves a low constraint state, the transfer of fracture toughness data from standard specimen to actual cracked components will produce a conservative result. The matching of constraint between structures and specimens is a key point for the developing of accurately structure integrity assessment method
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