Issue 47

Z. Hu et alii, Frattura ed Integrità Strutturale, 47 (2019) 383-393; DOI: 10.3221/IGF-ESIS.47.28 383 The Strain energy density to estimate lifetime of notched components subjected to variable amplitude fatigue loading Zheng Hu Science and Technology on Vehicle Transmission Laboratory, China North Vehicle Research Institute, Beijing, China, 100072 huzhengvip@126.com Filippo Berto Norwegian University of Science and Technology, NO-7491 Trondheim, Norway filippo.berto@ntnu.no , http://orcid.org/0000-0001-9676-9970 Luca Susmel Department of Civil and Structural Engineering, the University of Sheffield, Sheffield S1 3JD, UK l.susmel@sheffield.ac.uk , https://orcid.org/0000-0001-7753-9176 A BSTRACT . In the present paper, the approach based on the strain energy density (SED) averaged over a structural volume is reformulated to estimate the lifetime of notched components subjected to variable amplitude (VA) uniaxial fatigue loading. The accuracy and reliability of the proposed reformulation of the SED approach was checked against a large number of data taken from the literature and generated, under two different load spectra, by testing specimens of carbon steel C40 containing notches of different sharpness. Such a validation exercise allowed us to demonstrate that the extension of the SED approach as proposed in the present paper is capable of accurately estimating fatigue damage in notched components subjected to in- service VA fatigue loading. K EYWORDS . Strain energy density; Notch; Variable amplitude loading. Citation: Hu Z, Berto F, Susmel L, The Strain energy density to estimate lifetime of notched components subjected to variable amplitude fatigue loading, Frattura ed Integrità Strutturale, 47 (2019) 383-393. Received: 15.11.2018 Accepted: 04.12.2018 Published: 01.01.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION ost components contain material defects or geometric discontinuities. Examination of the state of the art demonstrate that the effect of stress concentrators on the fatigue strength of engineering materials has been investigated by considering mainly constant amplitude (CA) fatigue situations. However, most components experience variable amplitude (VA) fatigue load histories which make the characteristics of the critical local stress/strain states more complex, with this affecting markedly fatigue strength. M