Required Fatigue Strength (RFS) – A Simple Concept for Determining an Equivalent Stress Range Indicating the Necessary Minimum Joint Quality in Contrast to the Actual Modified Equivalent Strength (MES) Method

Required Fatigue Strength (RFS) – A Simple Concept for Determining an Equivalent Stress Range Indicating the Necessary Minimum Joint Quality in Contrast to the Actual Modified Equivalent Strength (MES) Method | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Required Fatigue Strength (RFS) – A Simple Concept for Determining an Equivalent Stress Range Indicating the Necessary Minimum Joint Quality in Contrast to the Actual Modified Equivalent Strength (MES) Method Joerg Baumgartner, Marco Breitenberger, Cetin Morris Sonsino This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4410977/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract This paper treats different FAT-scenarios for determining damage-equivalent stress ranges according to two methods for transforming a stress or load spectrum into a damage-equivalent constant amplitude loading, i.e., the Modified Equivalent Stress (MES) and the Required Fatigue Strength (RFS) concepts. The MES method is suggested by the IIW-recommendations for fatigue design and the RFS method is applied especially in the design of vehicle safety components. The resulting MES- and RFS-ranges are similar, but not equal. The MES-method delivers a damage-equivalent stress range that depends on the selected FAT-value, i.e., the position of the Woehler-curve is decisive. In contrast, the RFS-method results in a damage-equivalent fictitious Woehler-line that indicates the lowest necessary strength quality for a given stress spectrum. The allocation of the modified equivalent stress range to the appertaining bi-linear Woehler-curve does not result in the fatigue life caused by the spectrum. Only in the case of a linear Woehler-curve, the fatigue life is directly obtained. In the case of the RFS-application, the fatigue life is by definition equal to the spectrum length. For durability tests, the modified equivalent stress range (at L S cycles) and the associated FAT-Woehler-curve should not be used. However, the Woehler-curve derived by the RFS-method allows experimental durability proofs for any amplitude-cycle combination along it. Furthermore, the required lowest necessary strength also enables the selection of the most cost-effective manufacturing technique and quality. The RFS-Woehler-curve also results in a FAT-value with a defined probability of failure depending on the required safety factor. Fatigue variable amplitude loading modified equivalent stress range required fatigue strength range fatigue life probability of failure safety Full Text Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 31 May, 2024 Reviewers invited by journal 26 May, 2024 Editor invited by journal 24 May, 2024 Editor assigned by journal 15 May, 2024 First submitted to journal 14 May, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4410977","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":306939467,"identity":"000bd401-0a92-4926-ad99-bf86e57e1f65","order_by":0,"name":"Joerg Baumgartner","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0002-0225-275X","institution":"Fraunhofer Institute for Structural Durability and System Reliability LBF","correspondingAuthor":true,"prefix":"","firstName":"Joerg","middleName":"","lastName":"Baumgartner","suffix":""},{"id":306939468,"identity":"1c0c9f4a-52af-4e13-9bd0-d2124dd49d47","order_by":1,"name":"Marco Breitenberger","email":"","orcid":"","institution":"Fraunhofer-Institut fur Betriebsfestigkeit und Systemzuverlassigkeit LBF","correspondingAuthor":false,"prefix":"","firstName":"Marco","middleName":"","lastName":"Breitenberger","suffix":""},{"id":306939469,"identity":"85d4f12f-d9eb-4d36-bd3e-6714a6509473","order_by":2,"name":"Cetin Morris Sonsino","email":"","orcid":"","institution":"Fraunhofer-Institut fur Betriebsfestigkeit und Systemzuverlassigkeit LBF","correspondingAuthor":false,"prefix":"","firstName":"Cetin","middleName":"Morris","lastName":"Sonsino","suffix":""}],"badges":[],"createdAt":"2024-05-13 06:08:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4410977/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4410977/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":57886198,"identity":"da9fa75e-f3d9-48c0-9e62-fd7cbbe0ec3a","added_by":"auto","created_at":"2024-06-07 04:53:17","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2874352,"visible":true,"origin":"","legend":"","description":"","filename":"XIII29892023Baumgartner20240514.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4410977/v1_covered_3f1f6de3-dc3f-4140-a01e-3c9742bcd544.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eRequired Fatigue Strength (RFS) – A Simple Concept for Determining an Equivalent Stress Range Indicating the Necessary Minimum Joint Quality in Contrast to the Actual Modified Equivalent Strength (MES) Method\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Fatigue, variable amplitude loading, modified equivalent stress range, required fatigue strength range, fatigue life, probability of failure, safety ","lastPublishedDoi":"10.21203/rs.3.rs-4410977/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4410977/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis paper treats different FAT-scenarios for determining damage-equivalent stress ranges according to two methods for transforming a stress or load spectrum into a damage-equivalent constant amplitude loading, i.e., the Modified Equivalent Stress (MES) and the Required Fatigue Strength (RFS) concepts. The MES method is suggested by the IIW-recommendations for fatigue design and the RFS method is applied especially in the design of vehicle safety components. The resulting MES- and RFS-ranges are similar, but not equal.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe MES-method delivers a damage-equivalent stress range that depends on the selected FAT-value, i.e., the position of the Woehler-curve is decisive. In contrast, the RFS-method results in a damage-equivalent fictitious Woehler-line that indicates the lowest necessary strength quality for a given stress spectrum.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe allocation of the modified equivalent stress range to the appertaining bi-linear Woehler-curve does not result in the fatigue life caused by the spectrum. Only in the case of a linear Woehler-curve, the fatigue life is directly obtained. In the case of the RFS-application, the fatigue life is by definition equal to the spectrum length.\u003c/p\u003e\n\u003cp\u003eFor durability tests, the modified equivalent stress range (at \u003cem\u003eL\u003c/em\u003e\u003csub\u003e\u003cem\u003eS\u003c/em\u003e\u003c/sub\u003e cycles) and the associated FAT-Woehler-curve should not be used. However, the Woehler-curve derived by the RFS-method allows experimental durability proofs for any amplitude-cycle combination along it. Furthermore, the required lowest necessary strength also enables the selection of the most cost-effective manufacturing technique and quality. 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