PSI - Issue 18

Tatyana Tretyakova et al. / Procedia Structural Integrity 18 (2019) 837–842 Author name / Structural Integrity Procedia 00 (2019) 000–000

842

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In previous works we analyzed the evolution of inhomogeneous strain and local strain rate fields in AMg2m alloy at constant uniaxial tension rates. The analysis revealed the quasi-periodic strain field homogenization in jerky flow: alternating phases of active local plastic flow (shear banding) and macroscale strain levelling. Also analyzed are the parameters of localized microscale plastic flow such as the height and width of shear bands, their velocity, and coefficient of plastic strain inhomogeneity. From a series of mechanical tests, the influence of the specimen geometry and loading rate on these parameters was estimated. Researches have devoted considerable attention to the experimental investigation of the materials behavior under the effect of various additional loadings, including vibrations, which can be related to real conditions of operation of structures [Wildemann 2016]. The aim of the current work is to investigate the influence of additional vibration impact on spatial-time inhomogeneity of plastic flow due to the Portevin-Le Chatelier effect in metals during uniaxial tension tests. Figure 6 shows the loading diagrams obtained for Al-Mg alloy specimen: during uniaxial tension test and the uniaxial tension test with additional vibration. It should be noted that the additional vibration impact influences on the kinetics of the band nucleation and evolution. As can be seen from the Figure 6, the profiles of longitudinal strain for tests without and with vibration are significantly differ. The initiation and propagation of the strain bands become nonuniform and random. Conclusions Experimental data were obtained (diagrams, evolution of strain fields and local deformation rates, temperature fields, AE parameters) characterizing the material behavior and irregularities of the plastic flow due to the Chernov Lüders deformation and Portevin-Le Chatelier effect in metals. It was revealed that additional vibration impact during uniaxial tension tests influence on kinetics of the Chernov-Lüders and the Portevin-Le Chatelier bands. It is revealed the influence on the quasi-periodic character of the plastic flow. The initiation and propagation of the strain bands become nonuniform and random. Acknowledgements This work was carried out in Center of Experimental mechanics of Perm National Research Polytechnic University using Unique Scientific Equipment ‘Set of test and diagnostic equipment for study of properties of structural and functional materials under complex thermomechanical effects’ and funded by the Russian Science Foundation according to the research project № 18-79-00242. References Yilmaz, A., 2011. The Portevin-Le Chatelier effect: a review of experimental findings. Sci. Technol. Adv. Mater 12, 1‒16. Aguirre, F., Kyriakides, S., Yun, H.D., 2004. Bending of steel tubes with Lüders bands. International Journal of Plasticity 20, 1199–1225. Daghfas, O., Znaidi, A., Mohamed, A.B., Nasri, R., 2017. Experimental and numerical study on mechanical properties of aluminum alloy under uniaxial tensile test. Frattura ed Integrità Strutturale 39, 263‒273. Zhang, J., Jiang, Y., 2005. An experimental study of inhomogeneous cyclic plastic deformation of 1045 steel under multiaxial cyclic loading. International Journal of Plasticity 21, 2174–2190. Wildemann, V. E., Lomakin, E. V., Tretyakov, M. P., 2016. Effect of vibration stabilization of the process of postcritical deformation. Doklady Physics 61 (3), 147-151. Tretyakova, T.V., Wildemann, V.E., 2018. Plastic strain localization and its stages in Al-Mg alloys. Physical Mesomechanics 21 (4), 314-319.