PSI - Issue 40

A.V. Zinin et al. / Procedia Structural Integrity 40 (2022) 470–476 A.V. Zinin at al. / Structural Integrity Procedia 00 (2022) 000 – 000

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4. Conclusions (1) The influence of low-cycle overloads for a hardening material is manifested during subsequent fatigue loading as a softening effect if the structural state of the material corresponds to the second stage of the elastoplastic strain curve, characterized by the presence of a destructive component. (2) For a cyclically softening material, preliminary low-cycle training both in the area of elastoplastic strain ( low N = 5 cycles) and in the area of destructive strain development ( low N = 80 cycles), regardless of the strain amplitude ( a  = 0.2 and 0.5%), reduces the durability and endurance limit. (3) The influence of the component share of damage from preliminary overload in relation to real loading conditions is significant in some cases and requires consideration when calculating lifetime estimates. The ratio of change in the total lifetime in the presence of low-cycle overloads is proposed based on a linear model of damage accumulation. References Makhutov N. A., 2005. Structural Strength, Service Life and Technological Safety, Part 1 Criteria of Strength and Service Life [in Russian], Nauka, Novosibirsk, p.p.494. Romanov A. N., 2021. Local damage to structural materials under low-cycle loading. IOP Conference Series Materials Science and Engineering. 1023:012025. Smirnova L.L., Zinin A.V., 2021.A Study of Cyclic Fracture of Structural Materials Under Low-Cycle Overloads. Metal Science and Heat Treatment, 62, 759 – 764. Stepnov М. N., Zinin A. V., 2016. Prediction of Characteristics of Fatigue Resistance of Materials and Construction Component s [in Russian], Innovatsionnoe Mashinostroenie, Moscow, p.p.392. Romanov A. N.,1988. Fracture under Low-Cycle Loading [in Russian], Nauka, Moscow, p.p.278. Smirnova L. L., Zinin A. V., 2019. Structural features of accumulation of damage under combined cyclic loading. Zavod. Lab., Diagn. Mater., 85(5),46 - 51 (2019). Makhutov N.A., Gadenin M.M., 2019. Behavior of low-cycle damages accumulation taking into account loading service parameters [in Russian]. PNRPU Aerospace Engineering Bulletin, 56, 45-57. Chaboche J.-L., Kanoule P., Azzouz F., 2012. Cyclic inelastic constitutive equations and their impact on the fatigue life predictions. International Journal of Plasticity. 35, 44-66. Makhutov N. A., Frolov K. V., Gadenin M. M., et. al. 2006. Scientific Foundations for Raising Low-Cycle Strength [in Russian], Nauka, Moscow, p.p.623. Kesaev Kh. V., Trofimov R.S., 1982. Reliability of aircraft engines [in Russian], Mashinostroenie, Moscow, p.p.136. Kim Y., Woonbong H., 2019. High-Cycle, Low-Cycle, Extremely Low-Cycle Fatigue and Monotonic Fracture Behaviors of Low-Carbon Steel and Its Welded Joint. Materials.12(24), 41-51. Fatoba O., Akid R., 2018. Uniaxial cyclic elasto-plastic deformation and fatigue failure of API-5L X65 steel under various loading conditions. Theoretical and Applied Fracture Mechanics, S0167844217300575. Romanov A. N., Smirnova L. L., Merenkova R. F.,1979. Effect of low-cycle loads on fatigue of structural materials [in Russian] Metalloved. Term. Obrab. Met., 4, 34 -43. Rybakova L. M., 1980 Destruction of metal under volume and surface plastic deformation [in Russian]. Metatloved. Term. Obrab. Met., 8, 17-26. Zinin A. V., Bychkov N. G., Pershin A. V., et. al. 2017. Thermo-cycling strength of a refractory alloy and kinetics of accumulation of damage upon application of vibration loads [in Russian]. Zavod. Lab., Diagn. Mater., 83(2), 53 - 55. Sarkar A., Nagesha A., Parameswaran P., 2017. Evolution of damage under combined low and high cycle fatigue loading in a type 316LN stainless steel at different temperatures. International Journal of Fatigue. 103(4), 28 – 38. Laird C., 1977. Effect of dislocation substructures on fatigue fracture. Metallurgical Transactions A. 8, 51 – 860.