Issue 38

M. Sokovikov et alii, Frattura ed Integrità Strutturale, 38 (2016) 296-304; DOI: 10.3221/IGF-ESIS.38.40 298 The analysis of the fracture surface of samples with a transmission electron microscope has revealed the existence of the regions of band and honeycombed structures in the deformed layer in the strain localization areas. In order to study the properties of materials in a regime close a pure shear under dynamic loading conditions during the split Hopkinson (Kolsky) bar tests, we used the aluminum-magnesium alloy, containing 6%Mg “shear-compression” specimens having symmetrical notches on both sides and proposed in [5]. Figure 2 : Infrared image of the sample while it was undergoing deformation, and temperature distribution on the coordinate perpendicular to the shear area. The analysis of the fracture surface of samples with a transmission electron microscope has revealed the existence of the regions of band and honeycombed structures in the deformed layer in the strain localization areas (Fig.3), [6]. Figure 3 : Regions of band and honeycombed structures in the deformed layer in the strain localization areas. In order to study the properties of materials in a regime close a pure shear under dynamic loading conditions during the split Hopkinson (Kolsky) bar tests, we used the aluminum-magnesium alloy, containing 6%Mg, “shear-compression” specimens having symmetrical notches on both sides and proposed in [5]. Application of the high-speed infra-red camera CEDIP Silver 450M allowed us to investigate the distribution of plastic deformation under dynamic loading. The scheme of the experiment, tested specimen and temperature distribution are given in Fig.4. In-situ temperature fields were obtained during the process of deformation. Temperature in the area of plastic strain localization does not exceed ~70°С. The microstructure of the specimens was analyzed 3D fracture surface roughness using an optical interferometer-profiler, Fig.5. For dynamically deformed specimens, the constancy of Hurst index was observed over a much wider range of spatial scales in the comparison with quasi-static tests.