PSI - Issue 18

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Int grity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 18 (2019) 262–267

25th International Conference on Fracture and Structural Integrity The study of mechanical and microstructural aspects of localized shear fracture in metals under dynamic loading Mikhail Sokovikov a *, Sergey Uvarov a , Mikhail Simonov b , Vladimir Oborin a , Vasiliy Chudinov a , Oleg Naimark a 25th International Conference on Fracture and Structural Integrity The study of mechanical and microstructural aspects of localized shear fracture in metals under dynamic loading Mikhail Sokovikov a *, Sergey Uvarov a , Mikhail Simonov b , Vladimir Oborin a , Vasiliy Chudinov a , Oleg Naimark a

a Institute of Continuous Media Mechanics of the Ural Branch of the Russian Academy of Sciences, 1 Ak. Korolev Street, Perm, 614013 , Russia b Perm National Research Polytechnic University, 29 Komsomolskij Avenue , Perm, 614990, Russia a Institute of Continuous Media Mechanics of the Ural Branch of the Russian Academy of Sciences, 1 Ak. Korolev Street, Perm, 614013 , Russia b Perm National Research Polytechnic University, 29 Komsomolskij Avenue , Perm, 614990, Russia

Abstract The purpose of this work is to provide theoretical framework and experimental supporting evidence for a crucial role of structural transitions in the ensemble of defects at the meso-level (microshears and microcracks), as one of the mechanisms of plastic strain localization in metals under high-rate loading. The investigation of the sample response to dynamic loading was carried out on the split Hopkinson pressure bar and in a series of target penetration tests. To identify the characteristic stages of strain localization, the thermodynamics of the deformation process was investigated "in-situ" by recording the temperature fields using a high-speed infrared camera CEDIP Silver 450M. The temperature measured in the localization zone does not confirm the generally accepted concept of the strain localization mechanism as the mechanism governed by a thermoplastic instability. The samples stored after the experiment were subjected to microstructural analysis, using an optical interferometer-profilometer and a scanning electron microscope. The structural analysis revealed a correlated behavior of the ensemble of defects, which can be classified as a structural transition providing strain localization. The data of experimental studies, the examination of the structure of deformed samples, as well as the data of numerical modeling taking into account the kinetics of accumulation of microdefects in the material suggest that one of the mechanisms of plastic strain localization at high loading rates is associated with the jump-like processes in the defect structure of a material. Abstract The purpose of this work is to provide theoretical framework and experimental supporting evidence for a crucial role of structural transitions in the ensemble of defects at the meso-level (microshears and microcracks), as one of the mechanisms of plastic strain localization in metals under high-rate loading. The investigation of the sample response to dynamic loading was carried out on the split Hopkinson pressure bar and in a series of target penetration tests. To identify the characteristic stages of strain localization, the thermodynamics of the deformation process was investigated "in-situ" by recording the temperature fields using a high-speed infrared camera CEDIP Silver 450M. The temperature measured in the localization zone does not confirm the generally accepted concept of the strain localization mechanism as the mechanism governed by a thermoplastic instability. The samples stored after the experiment were subjected to microstructural analysis, using an optical interferometer-profilometer and a scanning electron microscope. The structural analysis revealed a correlated behavior of the ensemble of defects, which can be classified as a structural transition providing strain localization. The data of experimental studies, the examination of the structure of deformed samples, as well as the data of numerical modeling taking into account the kinetics of accumulation of microdefects in the material suggest that one of the mechanisms of plastic strain localization at high loading rates is associated with the jump-like processes in the defect structure of a material.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. © 2019 The Authors. Published by Elsevier B.V.

* Corresponding author. Tel.: +7-342-237-8312; fax: +7-342-237-8487 E-mail address: sokovikov@icmm.ru * Corresponding author. Tel.: +7-342-237-8312; fax: +7-342-237-8487 E-mail address: sokovikov@icmm.ru

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.162