PSI - Issue 18

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

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(Fig. 1, a). For example, Fig. 1 (b) shows the dependence of the voltage level (U), recorded on the channel of the synchronization unit, on the number of recorded frames. The red dashed line indicates the level of ‘trigger’ voltage.

Fig. 1. (a) The ‘Vic-Snap’ software of the video system in the ‘Analog Capture’ mode; (b) the dependence of the voltage level (U), recorded on the channel of the synchronization unit, on the number of recorded frames.

The use of this shooting algorithm and the loading program with short stops made it possible to analyze evolution of strain fields at the maximum load level in a cycle, and to minimize the influence of vibrations on the accuracy. It is seems to be relevant when we use high-resolution digital cameras with relatively low shooting speeds in tests with

vibration. 4. Results

The analysis of the effect of additional vibration effects on the patterns of initiation and propagation of Chernov Lüders bands in carbon steel 20 and aluminum-magnesium alloy in tests for uniaxial tension of flat specimens was carried out. Figure 2 illustrates the ‘load-displacement’ diagrams for carbon steel specimen. Curves 1 and 2 correspond to the uniaxial tension test and the uniaxial tension test with additional vibration accordingly.

Fig. 2. The ‘load-displacement’ diagrams of the flat specimens of carbon steel: 1 - uniaxial tension, 2 - uniaxial tension with additional vibration effect.

Figure 3 shows the evolution of the heterogeneous local strain rate fields on the surface of the carbon steel specimen due to the propagation of the single band of localized plastic flow due to the Chernov-Lüders deformation. This process corresponds to the stage of the yield drop and plateau forming. Figure 4 depicts the set of profiles of the longitudinal strain over the length of the working part of the dog-bone specimens. The time gap between profiles is 2 seconds. It is revealed that additional vibration has no effect on the process of the initiation and formation of the