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Publisher DOI: 10.3221/IGF-ESIS.44.05
Title: On notch and crack size effects in fatigue, Paris’ law and implications for Wöhler curves
Language: English
Authors: Ciavarella, Michele 
Papangelo, Antonio 
Keywords: Fatigue;Wöhler curve;Notch Sensitivity;Paris’ law;Ashby maps
Issue Date: 1-Apr-2018
Source: Frattura ed Integrita Strutturale 44 (12): 49-63 (2018-04-01)
Journal or Series Name: Frattura ed integrità strutturale 
Abstract (english): As often done in design practice, the Wöhler curve of a specimen, in the absence of more direct information, can be crudely retrieved by interpolating with a power-law curve between static strength at a given conventional low number of cycles N0(of the order of 10-103), and the fatigue limit at a “infinite life”, also conventional, typically N∞=2·106or N∞=107cycles. These assumptions introduce some uncertainty, but otherwise both the static regime and the infinite life are relatively well known. Specifically, by elaborating on recent unified treatments of notch and crack effects on infinite life, and using similar concepts to the static failure cases, an interpolation procedure is suggested for the finite life region. Considering two ratios, i.e. toughness to fatigue threshold FK=KIc/∆Kth, and static strength to endurance limit, FR=σR/∆σ0, qualitative trends are obtained for the finite life region. Paris’ and Wöhler’s coefficients fundamentally depend on these two ratios, which can be also defined “sensitivities” of materials to fatigue when cracked and uncracked, respectively: higher sensitivity means stringent need for design for fatigue. A generalized Wöhler coefficient, k’, is found as a function of the intrinsic Wöhler coefficient k of the material and the size of the crack or notch. We find that for a notched structure, k
DOI: 10.15480/882.2124
ISSN: 1971-8993
Institute: Strukturdynamik M-14 
Type: (wissenschaftlicher) Artikel
License: CC BY 4.0 (Attribution) CC BY 4.0 (Attribution)
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