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Combustion, Explosion and Shock Waves

2016 year, number 5

Specific Features of the Transformation of Spall Cracks to Localized Shear Bands

S. N. Buravova, E. V. Petrov, A. S. Shchukin
Institute of Structural Macrokinetics and Material Science Problems, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: ударная волна, разгрузка, интерференция, локализация, адиабатические полосы сдвига, откольное разрушение, shock wave, unloading, interference, localization, adiabatic shear bands, spall fracture


Investigations of specific features of the microstructure of the region where a spall crack transforms to an adiabatic shear band are based on a spall model of strain localization, which implies that adiabatic shear bands are induced by interference of unloading waves, and the value of the negative stress in the expansion region of these waves does not exceed the dynamic strength of the material. It is shown that the transition region contains a tremendous number of dislocation ensembles, which is much greater than the number of dislocation ensembles generated by a shock wave. Detection of micrometer-sized fracture sites in the region of interference of unloading waves implies that small fracture sites are formed in a polycrystalline material on dislocations arising in the course of dynamic tension.