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Effects of short cracks produced at blunted pre-crack tip on stress and strain distributions.
- Source :
-
International Journal of Fracture . Mar2005, Vol. 132 Issue 1, p33-48. 16p. - Publication Year :
- 2005
-
Abstract
- The present work investigates problems: (1) How are the plastic strain and the stress (triaxiality) re-distributed after a short crack initiated, extended and blunted at the pre-crack tip? (2) How do the above changes put a crucial effect on the triggering of the cleavage fracture? Based on the previous observations of configuration changes and fracture surfaces of pre-crack tips, Finite element method (FEM) simulations of a short crack initiated, extended and blunted at a pre-crack tip and calculations of distributions of stress, strain and triaxiality are carried out for 3PB pre-cracked HSLA steel specimens tested at -130°C. The results reveal that: as long as the fatigue pre-crack is only blunted, in its vicinity a region where the accumulated strain is sufficient to nucleate a crack, and a region where the stress (triaxiality) is sufficient to propagate a crack nucleus are separated by a distance. The nucleated crack cannot be propagated and the cleavage fracture cannot be triggered. While a short crack produced at the fully blunted fatigue pre-crack, the strain retains, the stress (triaxiality) is rebuilt. An initiated and significantly extended and then blunted short crack makes a tip configuration, which on one hand is much sharper than that of the fully blunted original pre-crack tip, on other hand is wide enough to spread its effects into the high stress covered region. This sharpened crack tip configuration re-builds a ‘sharper’ distribution of stress (triaxiality) and makes two regions metioned above closer. Finally the two regions overlap each other and a cleavage crack can be initiated and propagated at a distance ahead of the blunted fatigue pre-crack. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03769429
- Volume :
- 132
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- International Journal of Fracture
- Publication Type :
- Academic Journal
- Accession number :
- 16335027
- Full Text :
- https://doi.org/10.1007/s10704-004-5792-0