PSI - Issue 38

Available online at www.sciencedirect.com Structural Int grity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 38 (2022) 507–518

© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2021 Organizers © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2021 Organizers Abstract Fatigue is the main cause of failures of mechanical parts in service. Therefore, it seems essential to un er tand this behaviour throughout the design, manufacture, and validation cycle. Over the years, the S-N curve has demonstrated its efficiency in terms of its ability to establish a relationship between the stress state of a material (or a part) an its lifetime, especially whe this stress state is subjecte cyclically. Many mathematical models are known for their cap city to model this curve using experimental results, but the tools to define their parameters (slope, intercept, asymptotic limit, etc.) are much less so. The work presented in this article aims to resent the main methods of fitting S-N curves according to the most used mathematical models but also to propose a global approach applying to any type of model. © 2021 The Authors. Published by ELSEVIER B.V. This is an ope access article under t CC BY-NC-ND license (https://creativecommons.org/lic nses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2021 Organizers FATIGUE DESIGN 2021, 9th Edition of the International Conference on Fatigue Design A new generic method to analyse fatigue results Robin Hauteville, Xavier Hermite, Fabien Lefebvre Centre Technique des Industries Mécaniques (Cetim), Senlis, France Abstract Fatigue is the main cause of failures of mechanical parts in service. Therefore, it seems essential to understand this behaviour throughout the design, manufacture, and validation cycle. Over the years, the S-N curve has demonstrated its efficiency in terms of its ability to establish a relationship between the stress state of a material (or a part) and its lifetime, especially when this stress state is subjected cyclically. Many mathematical models are known for their capacity to model this curve using experimental results, but the tools to define their parameters (slope, intercept, asymptotic limit, etc.) are much less so. The work presented in this article aims to present the main methods of fitting S-N curves according to the most used mathematical models but also to propose a global approach applying to any type of model. FATIGUE DESIGN 2021, 9th Edition of the International Conference on Fatigue Design A new generic method to analyse fatigue results Robin Hauteville, Xavier Hermite, Fabien Lefebvre Centre Technique des Industries Mécaniques (Cetim), Senlis, France 1. Introduction Fatigue is subject to variability and therefore a defined number of experiments are needed to characterise the fatigue behaviour properties as efficiently as possible. These mechanical properties are critical because induce more than 80% of the in-service failure [1]. Fatigue behaviour must then be strongly considered in the design and manufacturing processes of mechanical equipment. Wöhler curves, also called S-N curves, are commonly used to estimate the lifetime of mechanical component subjected to fatigue under different stress levels. The characterisation of this fatigue behaviour model needs mathematical analysis of fatigue experiments results performed on standardised samples or on specific parts or equipment. Depending on the mathematical model used to characterise the fatigue behaviour of the studied system (Inverse Power or Basquin Law, Stromeyer Model, Bastenaire Model, Weibull Model, etc.), the evaluation of the parameters is more or less complex, and usually performed through the well-known least square regression method associated 1. Introduction Fatigue is subject to variability and therefore a defined number of experiments are needed to characterise the fatigue behaviour properties as efficiently as possible. These mechanical properties are critical because induce ore than 80% of the in-service failure [1]. Fatigue behaviour must then be strongly considered in the design and manufacturing processes of mechanical equipment. Wöhler curves, also called S-N curves, are commonly used to estimate the lifetime of mechanical component subjected to fatigue under different stress levels. The characterisation of this fatigue behaviour model needs mathe atical analysis of fatigue experiments results performed on standardised samples or on specific parts or equipment. Depending on the mathematical model used to characterise the fatigue behaviour of the studied system (Inverse Power or Basquin Law, Stromeyer Model, Bastenaire Model, Weibull Model, etc.), the evaluation of the parameters is more or less complex, and usually performed through the well-known least square regression method associated Keywords: Fatigue results analysis, maximum likelihood, parameter estimation, fatigue model Keywords: Fatigue results analysis, maximum likelihood, parameter estimation, fatigue model

2452-3216 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2021 Organizers 10.1016/j.prostr.2022.03.051 2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2021 Organizers 2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an ope acces article under CC BY-NC-ND lic nse (https://cr ativecommons.org/l c nses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2021 Organizers