PSI - Issue 48

Shanyavskiy A. et al. / Procedia Structural Integrity 48 (2023) 119–126 Shanyavskiy et al/ Structural Integrity Procedia 00 (2023) 000–000

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Recalculation of the obtained value of durability in hours gives a value of 3.05∙10 9 / (14150 ∙ 60) = 3592, which falls within the range of in-service life before failure given above in the description of flight accidents. In any case, this calculation confirms the possibility of realization of fatigue failure in gears Z 4 by the VHCF mechanism, especially taking into account the potential scatter of durability in the region of transition from high-cycle to very high-cycle fatigue. 5. Conclusion It is important to differentiate the causes of material fracture in the region of HCF and VHCF when finding the solution for both ensuring flight safety and a long service life of gears. Reducing the stress concentration on the surface, of course, will have a positive effect on increasing the life of the gears, but this will not solve the problem as a whole, because when operating more than 10,000 hours, gear failures are still observed, and their intensity will increase. This is due to the fact that in terms of stress state, the stress state of gears under consideration corresponds to the region of transition from VHCF to HCF. A decrease in stress concentration on surface, the absence of cementite inclusions near the surface will lead to a more pronounced subsurface initiation of fatigue cracks. Owing to the proposed multi-mode fatigue failure model with the computational algorithm, it was possible to simulate the developing of the fatigue failure process according to the VHCF mechanism for real stress state distribution, shape and strength parameters of the reducer gear under actual operating rotational speeds. Acknowledgements The research has been conducted under the Russian Science Foundation project no. 19-19-00705-P. References Burago, N., Nikitin, I., 2016. Multiaxial Fatigue Criteria and Durability of Titanium Compressor Disks in Low- and Very-high-cycle Fatigue Modes, in “Mathematical Modeling and Optimization of Complex Structures” . In: Neittaanmäki, P., Repin, S., Tuovinen, T. (Eds.). Springer, Heidelberg, pp. 117-130. Carpinteri, A., Spagnoli, A., Vantadori, S., 2011. Multiaxial Fatigue Assessment Using a Simplified Critical Plane-Based Criterion. International Journal of Fatigue 33, 969–976. Gates, N., Fatemi, A., 2016. Multiaxial Variable Amplitude Fatigue Life Analysis Including Notch Effects. International Journal of Fatigue 91, 337–351. Korablev, A.I., Reshetov, D.N., 1968. Increasing the Bearing Capacity and Durability of Gears. Mashinostroenie, Moscow. Lemaitre, J., Chaboche, J.L., 1994. Mechanics of Solid Materials. Cambridge University Press, Cambridge. Murakami, S., 2012. Continuum Damage Mechanics. A Continuum Mechanics Approach to the Analysis of Damage and Fracture. Springer, Dordrecht. Nikitin, I.S., Burago, N.G., Zhuravlev, A.B., Nikitin, A.D., 2020. Multimode Model for Fatigue Damage Development. Mechanics of Solids 55, 1432–1440. Nikitin, I.S., Burago, N.G., Nikitin, A.D., 2022. Damage and Fatigue Fracture of Structural Elements in Various Cyclic Loading Modes. Mechanics of Solids 57, 1793–1803. Shanyavskiy, A.A., 2007. Modelling of Metal Fatigue Fracture. Synergetics in Aviation. Monografy, Ufa. Shanyavskiy, A.A., Nikitin, A.D., Soldatenkov, A.P., 2022. Very-High-Cycle Fatigue of Metals. Synergetics and Physical Mesomechanics. Fizmatlit, Moscow. Shanyavskiy, A.A., Skvortsov, G.V., 1999. Crack Growth in the Gigacycle Fatigue Regime for Helicopter Gears. Fatigue & Fracture of Engineering Materials & Structures 22, 609–619. Shanyavskiy, A.A., Soldatenkov, A.P. 2022. Metallic Materials Fatigue Behavior: Scale Levels and Ranges of Transition between Them. International Journal of Fatigue 158, 106773. Shanyavskiy, A.A., Toushentsov, A.L., Soldatenkova, M.A., 2017. Very-High-Cycle Fatigue for the Conic Gears of Central Drive and Gearbox of PS-90A Engines, Proceedings of the ORAP. Russia, Moscow, pp. 210–217. Smith, K.N., Watson, P., Topper, T.H., 1970. A Stress-Strain Function for the Fatigue of Metals. Journal of Materials 5, 767–778.