PSI - Issue 41

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2022) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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ScienceDirect

Procedia Structural Integrity 41 (2022) 510–517

© 2022 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 MedFract2Guest Editors. Abstract The lifetime of VT6 (Ti-6Al-4V) titanium alloy under consecutive dynamic and very-high cycle fatigue loads is studied. The relevance of the problem is determined by the applications to the prediction of the endurance fatigue limit for materials and structural elements of aircraft gas turbine engines experiencing random dynamic effects under flight cycle conditions. The titanium alloy specimens were used to perform High Cycle Fatigue (HCF) and Very High Cycle Fatigue (VHCF) tests on the ultrasonic testing machine, which allows fatigue loading for 10 8 -10 10 cycles with amplitude up to several tens of micrometers and frequency of 20 kHz. It is shown that VT6 alloy specimens in the 10 8 cycle regime subject to dynamic preloading reduces the fatigue strength by 70%. Structural study of the fracture surface for the specimens after consecutive loading was conducted using the profilometry data to identify the roughness scale invariants induced by defects for corresponding areas responsible for the staging of fatigue damage-failure transition. The scale invariants and corresponding lengths were used to formulate the generalized Paris law governing the crack growth in damaged materials. © 2022 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 MedFract2Guest Editors. Keywords: Fracture, gigacycle fatigue, scaling, surface morphology, Paris law, crack growth kinetics; 2nd Mediterranean Conference on Fracture and Structural Integrity Damage-failure transition in VT6 titanium alloy under consecutive dynamic and VHCF loads Aleksandr Inozemtsev a , Oborin Vladimir b, *, Michail Bannikon b , Ivan Gladky a , Oleg Naimark b a Joint-Stock Company «UEC-Aviadvigatel» , 93, Komsomolsky prospect, Perm 614990, Russia b Institute of Continuous Media Mechanics of Ural branch of RAS, 1, Ac. Koroleva str., Perm 614013, Russia

* Corresponding author. Tel.: +7-342-2378-312. E-mail address: oborin@icmm.ru

2452-3216 © 2022 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 MedFract2Guest Editors.

2452-3216 © 2022 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 MedFract2Guest Editors. 10.1016/j.prostr.2022.05.058