SEDL / STP / STP1256-EB / STP16378S

Two-Parameter (J-Q) Fracture Characterization of Ductile Tearing

Wu, S-X
ARC research fellow and professor, University of Sydney, Sydney, NSW

Mai, Y-W
ARC research fellow and professor, University of Sydney, Sydney, NSW

Pages: 11    Published: Jan 1995

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Abstract

CTOD tests have been carried out for compact tension speci mens with a/W=0.6, double-edge notched tension specimens with a/W=0.9 and 0.5, single-edge notched tension specimens with a/W=0.5, three-point bend specimens with a/W=0.5 and 0.1 and center-cracked tension specimens with a/W=0.5. The results of the CTOD tests show that the crack initiation toughness of the material increases as the in-plane plastic constraint of the specimens decreases. The recently proposed two-parameter (J-Q) fracture characterisation technique has shown that the near-tip fields under very general conditions of loading in finite bodies can be described by two parameters, J and Q. A theoretical model of void nucleation and growth in the J-Q fields ahead of the crack tip is given in this paper. This model predicts the relationship between the crack initiation toughness (Jⁱ or δⁱ) and the constraint parameter Q. Comparison of experimental results of CTOD tests gives good agreement with theory.