Issue 38

A. Niesłony, Frattura ed Integrità Strutturale, 38 (2016) 177-183; DOI: 10.3221/IGF-ESIS.38.24 177 Focussed on Multiaxial Fatigue and Fracture A critical analysis of the Mises stress criterion used in frequency domain fatigue life prediction Adam Niesłony Opole University of Technology, Poland a.nieslony@po.opole.pl , http://orcid.org/0000-0002-1218-8341 A BSTRACT . Multiaxial fatigue failure criteria are formulated in time and frequency domain. The number of frequency domain criteria is rather small and the most popular one is the equivalent von Mises stress criterion. This criterion was elaborated by Preumont and Piefort on the basis of well-known von Mises stress concept, first proposed by Huber in 1907, and well accepted by the scientific community and engineers. It is important to know, that the criterion was developed to determine the yield stress and material effort under static load. Therefore the direct use of equivalent von Mises stress criterion for fatigue life prediction can lead to some incorrectness of theoretical and practical nature. In the present study four aspects were discussed: influence of the value of fatigue strength of tension and torsion, lack of parallelism of the SN curves, abnormal behaviour of the criterion under biaxial tension- compression and influence of phase shift between particular stress state components. Information contained in this article will help to prevent improper use of this criterion and contributes to its better understanding. K EYWORDS . Mises stress; Frequency domain; Multiaxial fatigue. Citation: Niesłony, A., A critical analysis of the Mises stress criterion used in frequency domain fatigue life prediction, Frattura ed Integrità Strutturale, 38 (2016) 177-183. Received: 05.05.2016 Accepted: 10.06.2016 Published: 01.10.2016 Copyright: © 2016 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 ultiaxial fatigue life criteria are used during fatigue life prediction to compute equivalent uniaxial strain or stress state. This procedure is essential for the calculation of final fatigue life based on uniaxial fatigue characteristics. There are many propositions of multiaxial fatigue failure criteria in the literature based on stress invariants, critical plane concept, integral criteria and other [1–3]. Most of them are defined in time domain and implemented for working on stress or strain time histories or on sets of amplitudes. There are only few propositions dedicated for frequency based fatigue life assessment were the frequency domain definition of the criterion is expected [4, 5]. One of them is the criterion of Equivalent von Mises Stress (EMS), which is nowadays more and more popular and well accepted by engineers [6]. In this paper advantages and possible risks of usage of this criterion are taken under discussion. Particular four aspects were presented in details which are causing significant effect on computed fatigue life:  differences between fraction of fatigue strength of pure tension and torsion and the value of square root of 3,  lack of parallelism of the S-N curves for pure tension and torsion, M