Fatigue crack growth in 350WT steel subjected to intermittent tensile overloads and compressive underloads


  1. Rushton, P.A.
  2. Taheri, F.
  3. Stredulinsky, D.C.
Corporate Authors
MARTEC Ltd, Halifax NS (CAN);Dalhousie Univ, Halifax NS (CAN) Dept of Civil Engineering;Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Previous investigations have shown that significant crack growth retardation in 350WT steel may be realized through the application of tensile overloads. However, the application of compressive underloads may appreciably reduce the retardation produced by previous tensile overloads. Unfortunately, compressive underloads are commonly neglected in parctice, or, at best, dealt with via an empirically adjusted stress ratio (R). Therefore, a combined experimental and analytical/numerical fatigue testing program was undertaken with the objective of investigating the effects of intermittently applied tensile overloads (OL) and compressive underloads (UL) on fatigue crack growth in center-cracked 350WT steel specimens. A significant amount of knowledge has been gained regarding this overload/underload interaction, the subsequent fatigue crack growth behavior, and the analytical and numerical characterization of such behavior. Experimental fatigue testing was performed on a total of 16 specimens, in which the stress ratio (R), the overload ratio (OLR), and the overload-to-underload ratio (OL/UL) were systematically varied. Modifications to the commonly used Wheeler model was proposed, allowing consideration of compressive underloading effects. The results of the proposed modifications will be indicated in a future publication. TRUNCATED
Fatigue crack growth;Fatigue cracks
Report Number
DREA-SR-2001-094-SES-VI-PAP-29 — Special Report
Date of publication
01 Oct 2001
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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