Transition from complex strained state to simple one under non-proportional loading: comparison of various approaches

• Published in: Transactions of the Krylov State Research Centre
• Main Author: Anton R. Filatov
• Format: Article in Journal/Newspaper
• Language: English; Russian
• Published: Krylov State Research Centre 2021
• Subjects: fatigue strength; non-proportional loading; complex strained state; critical plane; Naval architecture. Shipbuilding. Marine engineering; VM1-989; Icebreaker
• Online Access: https://doi.org/10.24937/2542-2324-2021-1-395-42-46; https://doaj.org/article/d7303346f5b94e10950ea82cfa3969d6

Object and purpose of research. This paper discusses ship structures. Its purpose is to compare the most common methods for transition from complex strained state to the simple one in calculations of fatigue strength under non-proportional loading. Materials and methods. This paper describes the method of absolute maximum principal stresses, the method of signed von Mises stresses, Sins method and critical-plane method. Main results. Analysis of time histories for design stresses obtained as per above-mentioned methods for the simplest examples of non-proportional loading. The comparison of these results was illustrated by a case study (loading of an icebreaker propulsion shaft). Conclusion. It is shown that, of all the methods discussed in this paper, only critical-plane method can fully take the loading process into account. None of the other methods can take into account the changes in orientation of principal stresses, so their results could be both somewhat too high and too low.