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Advances in Materials Science and Engineering
Volume 2014 (2014), Article ID 487410, 7 pages
Research Article

Analysis on the Behavior of Nonpropagating Fatigue Cracks under Steep Stress Gradients

1School of Aerospace Engineering and Applied Mechanics, Tongji University, Siping Road 1239, Shanghai 200092, China
2College of Science, Zhejiang Sci-Tech University, Hangzhou, Zhejiang 310018, China

Received 16 March 2014; Accepted 20 May 2014; Published 5 June 2014

Academic Editor: Rui Vilar

Copyright © 2014 Hao Wu and Qiuying Lu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A mechanism for the formation of nonpropagating fatigue cracks ahead of a notch root is presented. The stress gradients near the elongated notch root along with the propagation of short crack and the resulting nonpropagating crack lengths are estimated. The local stress which is higher than the unnotched material fatigue limit initiates the crack from a notch root and local steep stress gradient as a very important element leads to the nonpropagating crack. The value of depends on the material properties, and specimen geometry as well as applied loading. The characteristic size of the short crack which depends on the material properties associates with the fatigue stress concentration factor . The estimated values of are in fairly good agreement with the experimental values available.