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Title:Section and notch size effects in fatigue
Author(s):Baske, D.T.
Abstract:The influence of “size effects” on the fatigue strength of metals has been studied. These effects were separated into two categories: Size of “scale” effects associated with changes in section size or length when stress or strain gradients are absent, and size effects associated with geometrical stress concentrations that produce stress and strain gradients. The findings indicate that the effect of specimen size on fatigue strength when stress gradients are absent is volume controlled, and can be determined by a simple mathematical relation between fatigue strength and volume. In the presence of geometrical stress concentrations, size effects are controlled by a critical volume at the notch root and the severity of the stress or strain gradient. A means to determine the fatigue notch factor, Kf, was devised by identifying the zone of metal at the notch root which is thought to govern the fatigue process. Corrections were then developed for the effects of the stress gradient and critical volume in this zone. The resulting equation for Kf embodies these corrections and the theoretical elastic stress concentration factor, Kt. Experimental verification was obtained by testing notched plate specimens and by utilizing data from the literature. Predictions of Kf over fatigue lives of from 10^2 to 10^6 cycles were within 3 percent of experimental values when calculated in terms of stress and 8 percent in terms of strain.
Issue Date:1972-08
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 360
Genre:Technical Report
Sponsor:Naval Air Development Center, Warminster, PA, 72/08
Rights Information:Copyright 1972 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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