Evaluating fatigue life of materials and structures under low-cycle loading
DOI:
https://doi.org/10.7242/1999-6691/2017.10.1.2Keywords:
modeling, stress-strained state, plasticity, low-cycle fatigue, mechanics of deformed media, damage accumulation, strength, durability, failure, service lifeAbstract
The problem of evaluating strength and fatigue life of critical engineering objects, the operational properties of which are characterized by multi-parametric nonstationary thermal-mechanical effects, is discussed. The main degradation mechanisms of structural materials (metals and their alloys) characteristic of such objects are considered. The main requirements for mathematical models of fatigue damage accumulation are formulated. To evaluate the stress-strained state (SSS) and fatigue life of critical engineering facilities (CEF) in the framework of modern achievements of mechanics of damaged media (MDM), a mathematical model is developed which describes the processes of cyclic thermal-plastic deformation and fatigue damage accumulation in structural alloys subject to multiaxial non-proportional paths of combined thermal-mechanical loading. The MDM model consists of three interconnected parts: thermal plasticity constitutive equations, accounting for their dependence on the failure process; an evolution equation of damage accumulation and a strength criterion of a damaged material. To qualitatively and quantitatively assess the constitutive relations of MDM for low-cycle modes of thermal-cyclic loading, the numerical and experimental results for the fatigue life of a notched compact sample in a non-uniaxial stress state under block modes of thermal-cyclic loading were compared, which supported the validity of the constitutive relations of the MDM model for thermal fatigue. An approach based on the Palmgren-Miner rule of linear summation of damage, when used for evaluating the fatigue life of structural elements, may result in both conservative and non-conservative estimates. This conclusion is confirmed by the experimental and theoretical studies of foreign and domestic authors. The results of numerical modeling of the fatigue durability of a compact specimen with an obtuse notch are presented for two loading histories. It is shown that several cycles of more intensive loading at the beginning of the strain history are the reason why the rule of linear summation of damage can overestimate or underestimate the value.
Downloads
References
Mitenkov A.F., Kajdalov V.B, Korotkih U.G. Metody obosnovania resursa adernyh energeticeskih ustanovok. - M.: Masinostroenie, 2007. - 448 s.
2. Mitenkov F.M., Korotkih U.G. K voprosu o sozdanii ekspluatacionnogo monitoringa resursa oborudovania i sistem adernyh energeticeskih ustanovok // Problemy masinostroenia i nadeznosti masin. - 2003. - No 4. - S. 105-116.
3. Volkov I.A., Korotkih U.G. Uravnenia sostoania vazkouprugoplasticeskih sred s povrezdeniami. - M.: Fizmatlit, 2008. - 424 s.
4. Kollinz Dz. Povrezdenie materialov v konstrukciah. Analiz, predskazanie, predotvrasenie. - M.: Mir, 1984. - 624 s.
5. Ellyin F., Kujawski D. An energy-based fatigue failure criterion // Microstructure and mechanical behaviour of materials, EAMS / Ed. by G.U. Haicheng, H.E. Jiawen. - 1986. - Vol. 2/2. - R. 541-600.
6. Trosenko V.T. Deformirovanie i razrusenie metallov pri mnogociklovom nagruzenii. - Kiev: Naukova dumka, 1981. - 342 s.
7. Perzina P. Modelirovanie zakriticeskogo povedenia i razrusenia dissipativnogo tverdogo tela // Trudy Amer. ob-va inz.-meh. Ser. D. Teoret. osnovy inz. rascetov. - 1984. - T. 106, No 4. - S. 107-117. DOI
8. Bojl Dz., Spens Dz. Analiz naprazenij v konstrukciah pri polzucesti. - M.: Mir, 1986. - 360 s.
9. Chaboche J.-L. Continuous damage mechanics - A tool to describe phenomena before crack initiation // Nucl. Eng. Des. - 1981. - Vol. 64, no. 2. - R. 233-247. DOI
10. Garud. Novyj podhod k rascetu ustalosti pri mnogoosnyh nagruzeniah // Trudy Amer. ob-va inz.-meh. Ser. D. Teoret. osnovy inz. rascetov. - 1981. - T. 103, No 2. - S. 41-51. DOI
11. Bodner, Lindholm. Kriterii prirasenia povrezdenij dla zavisasego ot vremeni razrusenia materialov // Trudy Amer. ob-va inz.-meh. Ser. D. Teoret. osnovy inz. rascetov. - 1976. - T. 96, No 2. - S. 51-53. DOI
12. Romanov A.N. Razrusenie pri malociklovom nagruzenii. - M.: Nauka, 1988. - 279 s.
13. Novozilov V.V. O plasticeskom razryhlenii // PMM. - 1965. - T. 29, No 4. - S. 681-689. DOI
14. Lemetr Z. Kontinual’naa model’ povrezdenia, ispol’zuemaa dla rasceta razrusenia plasticnyh materialov // Trudy Amer. ob-va inz.-meh. Ser. D. Teoret. osnovy inz. rascetov. - 1985. - T. 107, No 1. - S. 90-97. DOI
15. Sosi D. Modeli razrusenia pri mnogoosnoj ustalosti // Trudy Amer. ob-va inz.-meh. Ser. D. Teoret. osnovy inz. rascetov. - 1988. - T. 110, No 9.- S. 9-21. DOI
16. Volkov I.A., Korotkih U.G., Tarasov I.S. Modelirovanie sloznogo plasticeskogo deformirovania i razrusenia metallov pri mnogoosnom neproporcional’nom nagruzenii // PMTF. - 2009. - T. 50, No 5. - S. 193-205. DOI
17. Volkov I.A., Korotkih U.G., Tarasov I.S. Cislennoe modelirovanie nakoplenia povrezdenij pri sloznom plasticeskom deformirovanii // Vycisl. meh. splos. sred. - 2009. - T. 2, No 1. - S. 5-18. DOI
18. Volkov I.A, Korotkih U.G. Modelirovanie processov ustalostnoj dolgovecnosti materialov i konstrukcij pri malociklovom nagruzenii // MTT. - 2014. - No 3. - S. 66-78. DOI
19. Sobolev N.D., Egorov V.I., Pirogov E.N. Izucenie nakoplenia povrezdenij v usloviah neodnorodnogo naprazennogo sostoania pri termoustalostnom nagruzenii // Procnost’ i deformacia materialov v neravnomernyh fiziceskih polah / Pod red. A.B. Fridmana. - M.: Atomizdat, 1968. - Vyp. II. - S. 26-33.
20. Miheev M.A., Miheeva I.M. Osnovy teploperedaci. - M.: Energia, 1977. - 344 s.
21. Kiselev E.V., Kut’in V.B., Matuhin V.I. Elektriceskie peci soprotivlenia: Uceb. posobie. - Ekaterinburg: UGTU-UPI, 2010. - 79 s.
22. Volkov I.A., Igumnov L.A., Sisulin D.N., Tarasov I.S., Guseva M.A. Ocenka ustalostnoj dolgovecnosti kompaktnogo obrazca s koncentratorami pri termocikliceskom nagruzenii v usloviah neodnorodnogo naprazennogo sostoania // Problemy procnosti i plasticnosti. - 2016. - T. 78, No 3. - S. 333-349.
23. Dauling N.E. Rascet ustalostnoj dolgovecnosti pri sloznyh istoriah nagruzenia // Trudy Amer. ob-va inz.-meh. Ser. D. Teoret. osnovy inz. rascetov. - 1983. - T. 105, No 3. - S. 69-79. DOI
24. Volkov I.A., Tarasov I.S., Fomin M.N., Ereev M.N. Cislennyj analiz ustalostnoj dolgovecnosti kompaktnogo obrazca s zatuplennym vyrezom pri blocnyh rezimah malociklovogo nagruzenia // Vestnik naucno-tehniceskogo razvitia. - 2011. - No 1(41). - S. 39-51.
Downloads
Published
Issue
Section
License
Copyright (c) 2017 Computational Continuum Mechanics
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.