Issue 41

E. Tolmacheva (Lyapunova) et alii, Frattura ed Integrità Strutturale, 41 (2017) 552-561; DOI: 10.3221/IGF-ESIS.41.65 559 Figure 10 : The width of comminuted area in the vicinity of the indenter tip at different depths of its penetration in the sample. The 3 rd tomography image illustrates the way of determining the width W. It is important that cracks formation begins not at the indenter hole, as might be expected, but at the comminuted area (Figs. 8 and 10). The ImageJ software allowed us to calculate the volumetric porosity in the comminuted area, cracked area and in region far from the process zone, which can be considered as an undisturbed area (Fig. 11). There are no points corresponding to the first amplitude of the applied load (for the sample numbered 1 in Figs. 7 and 9), because there is no cracked area for such low magnitude of the applied load. It can be seen from Fig. 11, that the comminuted area porosity is about 3 % and is practically the same for all values of the applied loads, whereas the porosity in the cracked region is an order of magnitude higher and increases with increase of the applied load from ~34 % for ~1200 N to ~45 % for ~1900 N. Porosity in the undistributed region varies between 10 and 14 % and according to rough estimation it can be considered as the initial porosity of the material.