Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?

Fatigue tests run-out specimens up to 106 – 5x107 load cycles are used to determine the stress level named “fatigue limit”. Nevertheless, it is not clear what kind of fatigue cracking takes or will take place in these specimens. To discuss this problem, fatigue tests of titanium alloy VT3-1 specimen...

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Main Author: A. Shanyavskiy
Format: Article
Language:English
Published: Gruppo Italiano Frattura 2015-09-01
Series:Fracture and Structural Integrity
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Online Access:https://www.fracturae.com/index.php/fis/article/view/1572
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author A. Shanyavskiy
author_facet A. Shanyavskiy
author_sort A. Shanyavskiy
collection DOAJ
description Fatigue tests run-out specimens up to 106 – 5x107 load cycles are used to determine the stress level named “fatigue limit”. Nevertheless, it is not clear what kind of fatigue cracking takes or will take place in these specimens. To discuss this problem, fatigue tests of titanium alloy VT3-1 specimens have been performed under tension with different values of R-ratio and under rotating-bending after various thermo-mechanical treatments (tempering, surface hardening and their combinations). Well-known S-N curves in High-Cycle- Fatigue regime have been plotted with run-out specimens usually used for “fatigue limit” determination. Then, after fatigue tests, run-out specimens have been tensed up to their failure, and fracture surface analyses have been performed for all tested specimens. It is found that run-out specimens in all combinations of treatments, for different R-ratio, have fracture surfaces for crack path in Very-High-Cycle-Fatigue regime. Based on this result, all S-N curves have been reconstructed in duplex curves for High- and Very-High-Cycle-Fatigue regime without using knowledge about “fatigue limit”. Detailed fracture surfaces analyses have been developed, and crack paths have been compared for various combinations of materials and surface states.
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spelling doaj-art-76195d38814846719596fcad0ebd5f092025-01-03T00:39:57ZengGruppo Italiano FratturaFracture and Structural Integrity1971-89932015-09-01934Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?A. ShanyavskiyFatigue tests run-out specimens up to 106 – 5x107 load cycles are used to determine the stress level named “fatigue limit”. Nevertheless, it is not clear what kind of fatigue cracking takes or will take place in these specimens. To discuss this problem, fatigue tests of titanium alloy VT3-1 specimens have been performed under tension with different values of R-ratio and under rotating-bending after various thermo-mechanical treatments (tempering, surface hardening and their combinations). Well-known S-N curves in High-Cycle- Fatigue regime have been plotted with run-out specimens usually used for “fatigue limit” determination. Then, after fatigue tests, run-out specimens have been tensed up to their failure, and fracture surface analyses have been performed for all tested specimens. It is found that run-out specimens in all combinations of treatments, for different R-ratio, have fracture surfaces for crack path in Very-High-Cycle-Fatigue regime. Based on this result, all S-N curves have been reconstructed in duplex curves for High- and Very-High-Cycle-Fatigue regime without using knowledge about “fatigue limit”. Detailed fracture surfaces analyses have been developed, and crack paths have been compared for various combinations of materials and surface states.https://www.fracturae.com/index.php/fis/article/view/1572Fatigue limit
spellingShingle A. Shanyavskiy
Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?
Fracture and Structural Integrity
Fatigue limit
title Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?
title_full Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?
title_fullStr Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?
title_full_unstemmed Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?
title_short Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?
title_sort crack path for run out specimens in fatigue tests is it belonging to high or very high cycle fatigue regime
topic Fatigue limit
url https://www.fracturae.com/index.php/fis/article/view/1572
work_keys_str_mv AT ashanyavskiy crackpathforrunoutspecimensinfatiguetestsisitbelongingtohighorveryhighcyclefatigueregime