PSI - Issue 50

Alexander Inozemtsev et al. / Procedia Structural Integrity 50 (2023) 119–124 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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In some regions, the processes of localized shear band fragmentation and formation of submicrocrystalline structure with grain/subgrain sizes of about 80-120 nm were observed systematically. The obtained data testify to the presence of pronounced evolution processes in the defect subsystems during dynamic deformation. Among the important characteristic features are the recrystallisation-polygonisation processes, which occur in front of the resulting localized shear band, leading to the formation of a fine-crystalline structure. If, in the process of growing, the localized shear band comes across an obstacle in the form of inclusion or second- phase segregation fields, the crystal growth in this direction is inhibited or completely ceases, which results in compensation due to structural transfigurations in the surrounding material. At such locations, the formation of a vortex structures (vortex effect or turbulation) in the deformed material is the phenomenon of frequent occurrence. 3. Numerical calculation The strain fields in the zone of plastic shear localization in specially shaped specimens made of AlMg6 alloy were determined experimentally under conditions of dynamic loading on the split Hopkinson pressure bar using for this purpose the StrainMaster strain measurement system. Errors of the displacement and shear strain measurements are ~5%. In the framework of this study, we performed numerical simulation of conducted experiments, taking into account the evolution of mesolevel defects, Bilalov D.A. at al. (2018). The strain fields in the U-shaped specimens of AlMg6 alloy determined in the split Hopkinson pressure bar tests using the StrainMaster deformation measurement system and the results of numerical simulation are shown in Figure 3. The calculated strain fields and the experimental data were found to agree with an accuracy of ~20%.

Fig. 3. Distribution of absolute value ε xx – ε yy at the finite moment of time for U-shaped AlMg6 alloy specimen under dynamic loading: experiment (a), numerical simulation (b). 4. Conclusion The values of temperature fields determined by high strain rate testing of the U-shaped AlMg6 alloy specimens in the SHPB system using infrared thermography, the results of the StrainMaster system-based dynamic experiments, the study of deformed specimens structure, as well as the results of numerical simulation done with account for the specific features of kinetics of mesodefect accumulation, Bilalov D. A. at al. (2018), Sokovikov M.A. at al. (2020), lend support to the view that und the realized loading conditions one of the mechanisms of plastic strain localization in the AlMg6 alloy is related to the jump-like processes in the defect structure of the material. Acknowledgements The research was supported by the Russian Science Foundation (project no. 21-79-30041).