PSI - Issue 16

Roman Chepil et al. / Procedia Structural Integrity 16 (2019) 211–217

216

Roman Chepil, Olena Stankevych, Orest Ostash, Bohdan Klym / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. The damage accumulation (а) and AE monitoring of the fatigue micro - and macrocrack initiation (b) in notched specimen made of D16pchAT aluminum alloy at * y  = 390 MPa.

5. Conclusions

The regularities of early stages of fatigue failure , in particular, the microdamage accumulation, microcrack network formation and macrocrack initiation have been confirmed. The possibility of this process monitoring by means of non-destructive control was shown basing on the acoustic emission signals parameters: the amplitude of signals, their numbers, and forms. It was established that during accumulation of the microplastic deformations and the microcrack network formation until the macrocrack initiation, the energy parameter AE ( E WT ) increased from 0.01 to 0.18 for D16pchAT aluminum alloy (type 2024-T3) notched specimens. This makes it possible to identify the type (ductile or brittle) and the stage of fracture by parameter E WT value. DuQuesnay, D.L., Yu, M.T., Topper, T.H., 1998. An analysis of notch-size effects at the fatigue limit. Journal of Testing and Evaluation 16, 375  385. El Haddad, M.A., Topper, T.H., Smith, K.N., 1979. Prediction of non-propagating cracks. Engineering Fracture Mechanics 11, 573  584. Hu, Z., Berto, F., Hong, Yo., Susmel, L., 2019. Comparison of TCD and SED methods in fatigue lifetime assessment. International Journal of Fatigue 123, 105  134. Kryzak, D., Robak, G., Lagoda, T., 2017. Non-local line method for notched elements with use of effective length calculated in an elasto-plastic condition. Fatigue & Fracture of Engineering Materials & Structures 40, 89  102. Muravsky, L.I., Picart, P., Kmet', A.B., Voronjak, T.I., Ostash, O.P., Stasyshyn, I.V., 2016. Evaluation of fatigue process zone dimensions in notched specimens by two-step phase-shifting interferometry technique. Optical Engineering 55 (10), paper #104108. Nazarchuk, Z.T., Skalsky, V., 2009. Acoustic-emission diagnostics of structural components (in 3 vol.). Vol. 3: Means and application of the acoustic emission method. Naukova dumka, Kyiv. (In Ukrainian) Noroozi, A.H., Glinka, G., Lambert, S., 2005. A two parameter driving force for fatigue crack growth analysis. International Journal of Fatigue 27, 1277  1296. Ostash, O.P., Panasyuk, V.V., Kostyk, Ye.M., 1999. A phenomenological model of fatigue macrocrack initiation near stress concentrators. Fatigue & Fracture of Engineering Materials & Structures 22, 161  172. Ostash, O.P., Panasyuk, V. V., 2001. Fatigue process zone at notches. International Journal of Fatigue 23, 627  636. Ostash, O.P., Panasyuk, V. V., 2003. A unified approach to fatigue macrocrack initiation and propagation. International Journal of Fatigue 25, 703  708. Ostash, O.P., 2006. New approach in fatigue fracture mechanics. Materials Science 42, 5  19. Ostash, O.P., Chepil, R.V., Vira, V.V., 2010. Fatigue crack initiation and propagation at different stress ratio values of uniaxial pulsating loading. Fatigue & Fracture of Engineering Materials & Structures 34, 430  437. Ostash, O.P., Muravs’kyi , L.I., Voronyak, T. I., Kmet’ , A.B., Andreiko, I.M., Vira, V.V., 2011. Determination of the size of the fatigue prefracture zone by the method of phase-shifting interferometry. Materials Science 46, 781  788. Ostash, O.P., Chepil, R.V., Vira, V.V., 2017. The assessment of fatigue life of notched components at uniaxial pulsating loading using the fracture mechanics approach. International Journal of Fatigue 105, 305  311. References