An investigation of crack-tip stress field criteria for predicting cleavage-crack initiation
- Oak Ridge National Lab., TN (USA)
- Tennessee Univ., Knoxville, TN (USA). Dept. of Engineering Science and Mechanics
Cleavage crack initiation in large-sale wide-plate (WP) specimens could not be accurately predicted from small compact (CT) specimens utilizing a linear elastic fracture mechanics, K{sub Ic}, methodology. In the wide-plate tests conducted by the Heavy-Section Steel Technology Program at Oak Ridge National Laboratory, crack initiation has consistently occurred at stress intensity (K{sub I}) values ranging from two to four times those predicted by the CT specimens. Studies were initiated to develop crack-tip stress field criteria incorporating effects of geometry, size, and constraint that will lead to improve predictions of cleavage initiation in WP specimens from CT specimens. The work centers around nonlinear 2-D and 3-D finite-element analyses of the crack-tip stress fields in these geometries. Analyses were conducted on CT and WP specimens for which cleavage initiation fracture had been measured in laboratory tests. The local crack-tip field generated for these specimens were then used in the evaluation of fracture correlation parameters to augment the K{sub I} parameter for predicting cleavage initiation. Parameters of hydrostatic constraint and of maximum principal stress, measured volumetrically, are included in these evaluations. The results suggest that the cleavage initiation process can be correlated with the local crack-tip fields via a maximum principal stress criterion based on achieving a critical area within a critical stress contour. This criterion has been successfully applied to correlate cleavage initiation in 2T-CT and WP specimen geometries. 23 refs., 17 figs., 5 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- NRC
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6676328
- Report Number(s):
- CONF-900610-1; ON: DE90015597
- Country of Publication:
- United States
- Language:
- English
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