PSI - Issue 50

R.S. Akhmetkhanov et al. / Procedia Structural Integrity 50 (2023) 6–10 R.S.Akhmetkhanov / Structural Integrity Procedia 00 (2019) 000 – 000

8

3. Methodology In order to assess the differences in the thermogram images, the proposed method of thermogram analysis introduces the acquisition and subsequent analysis of the images of the thermal field (skeleton). The skeleton lines show the direction of the region of increased plastic deformation and the directions of the sliding planes. 4. Results Fig. 4 shows the ossification images of thermograms (ImageJ program), where regions of elevated temperature are clearly marked. By analyzing skeleton lines, local levels of plastic deformation can be identified - using these lines, it is possible to determine temperature change diagrams along the length of these lines (line profiles).

Fig.2. Stress levels in the sample: (a) at strain  1

ij ; (b) at strain  2

2

1

ij , ( 

ij )

ij > 

Fig. 3. Thermograms at general deformation: ( а )  1

ij ; ( b)  2

2

1

ij; ( 

ij )

ij > 

At the initial stage of specimen loading, zones with increased temperature are manifested in two areas (1 and 2, fig. 4a), which are characterized by small plastic deformation slip lines. Later, as the load increases, significant slip lines 1,2 and 3 are formed (fig. 4b), as well as a small area in the form of a "star" 4 (fig. 4b) - the defect area.