PSI - Issue 5

Valeriy Lepov et al. / Procedia Structural Integrity 5 (2017) 777–784 Valeriy Lepov et al / Structural Integrity Procedia 00 (2017) 000 – 000

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4. Conclusion

The mechanical properties and structure evaluation after the weld and low-cycle loading is significant for structural members of transport system. The differences in failure for low-cycling fatigue test probes caused by weld defects and heterogeneity could be modeled both by mechanics of continua and fracture mechanics. The influence of the mechanical heterogeneity in the low-alloyed steel welded probes on state-strain state and crack resistance has been estimated by the FE and stochastic modelling. Common defects were noticed on some welded samples, and these samples during the tensile test were broken on the welded zone under the normal estimated tensile strength and before the elastic limit. This failure could be as a result of one of the following reasons: poor welding procedure specification, poor welding skills, amongst others. The new criterion and approach of damage estimation for locomotive tire in extreme uncertainty conditions are offered. It is revealed that the lifetime of tire is significantly sensitive to impact strength at low temperature during operation. The new visualization possibilities of programming of damage accumulation and fracture processes has been presented also. The possibility of crack growth under the low-cycling and dynamic load, and in cases of complex loading is examined. To avoid the catastrophic failure of welded structures, special techniques should be applied to reduce hardness of the material. Systematic monitoring of structures like railway, locomotive tire, bridges, pipe lines, energy stations and buildings is necessary. One of the good methods of nondestructive testing could be the microhardness control of the weld and heat affected zone to avoid the significant modification of mechanical properties of welded structures. Al-Najjar, N.I., Weinstein J., 2015, A Bayesian model of Knightian uncertainty, Theory Dec. 78, 1 – 22. Arkhangelskaya, E.A., Lepov, V.V., Larionov, V.P., 2003, The Role of Defects in the Development of Delayed Fracture of a Damaged Medium under the Effect of Hydrogen, Materialovedenie 8, 7 – 10. Broberg, K.B., 1990, Computer demonstration of crack growth, Int. J. Fracture 42, 277-285. Broek, D., 1982, Elementary engineering fracture mechanics, Martinus Nijhoff Publishers, Boston. Cherepanov, G.P., 1974, Mechanics of Brittle Fracture, Nauka Press, Moscow. Computational and Experimental Methods in Structures: Vol.3. Multiscale Modeling in Solid Mechanics, 2009, ed. Ugo Galvanetto and M.H. Ferri Aliabadi, World Scientific, London. Goryacheva, I.G., Soshenkov, S.N., and Torskaya, E.V., 2013, Modelling of Wear and Fatigue Defect Formation in Wheel-Rail Contact, Vehicle Syst. Dyn. 51, 6, 767 – 783. Griffith, A.A., 1920, The phenomenon of rupture and flow in solids, Phil. Trans. Roy. Soc. Ser. A 221, 163 – 198. Fracture. An Advanced Treatise, ed. Liebovitz, H., 1968, Academic Press, New York and London. Hell, S.W., et al, 2015, The 2015 super-resolution microscopy roadmap, J. Phys. D: Appl. Phys. 48, 443001 Ιο ffe, A.F., 1928, The Physics of Crystals, McGraw Hill, New York and London. Lepov, V., Ivanova, A., Achikasova, V., Lepova, K., 2007, Modeling of the damage accumulation and fracture: structural-statistical aspects, Key Engineering Materials 345-346, I, 809-812. Lepov, V.V., et al., 2008, The Mechanism of Nanostructured Steel Fracture at Low Temperatures, Nanotechnologies in Russia 3, 734 – 742 Lepov, V., Grigoriev, A., Achikasova, V., Lepova, K., 2016, Some Aspects of Structural Modeling of Damage Accumulation and Fracture Processes in Metal Structures at Low Temperature, Modelling and Simulation in Engineering 2016, 7178028. Lepov, V., Mbelle, S.B., 2017, Microhardness and Elasticity Study of Fatigue Tested Weld Samples, DEStech Transactions on Engineering and Technology Research, International Conference on Mechanical and Mechatronics Engineering (ICMME 2017), 8611. Acknowledgements This research has been partially supported by Russian Foundation for Basic Research (Project 15-41-05010) and Federal Agency of Scientific Organization of Ministry of Science and Education of Russian Federation. References