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Predicting dwell fatigue life in titanium alloys using modelling and experiment

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Title: Predicting dwell fatigue life in titanium alloys using modelling and experiment
Authors: Xu, Y
Joseph, S
Karamched, P
Fox, K
Rugg, D
Dunne, F
Dye, D
Item Type: Journal Article
Abstract: Fatigue is a difficult multi-scale modelling problem nucleating from localised plasticity at the scale of dislocations and microstructure with significant engineering safety implications. Cold dwell fatigue is a phenomenon in titanium where stress holds at moderate temperatures lead to substantial reductions in cyclic life, and has been implicated in service failures. Using discrete dislocation plasticity modelling complemented by transmission electron microscopy, we successfully predict lifetimes for ‘worst case’ microstructures representative of jet engine spin tests. Fatigue loading above a threshold stress is found to produce slip in soft grains, leading to strong dislocation pile-ups at boundaries with hard grains. Pile-up stresses generated are high enough to nucleate hard grain basal dislocations, as observed experimentally. Reduction of applied cyclic load alongside a temperature excursion during the cycle lead to much lower densities of prism dislocations in soft grains and, sometimes, the elimination of basal dislocations in hard grains altogether.
Issue Date: 17-Nov-2020
Date of Acceptance: 7-Oct-2020
URI: http://hdl.handle.net/10044/1/84699
DOI: 10.1038/s41467-020-19470-w
ISSN: 2041-1723
Publisher: Nature Research
Journal / Book Title: Nature Communications
Volume: 11
Copyright Statement: © The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Royal Academy Of Engineering
Rolls-Royce Plc
Funder's Grant Number: EP/K034332/1
Publication Status: Published
Article Number: ARTN 5868
Appears in Collections:Materials
Faculty of Natural Sciences

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