PSI - Issue 65

I. Shardakov et al. / Procedia Structural Integrity 65 (2024) 233–240 237 I. Shardakov, R. Tsvetkov, I. Glot, A. Shestakov, G. Gusev, V. Yepin / Structural Integrity Procedia 00 (2024) 000–000 5

Figure 3 shows the number of single acoustic pulses recorded by sensor 1 at 7 different characteristic stages of loading (steps, 7, 10, 12, 18, 22, 34, 37). The figure demonstrates the correlation between AE processes and deformation processes developing in the structure with increasing load. It clearly shows increase in the number of pulses as the load increases; the absence of acoustic pulses in the range of loads less than 50 kN (elastic deformation) and rapid increase in AE activity at stages where the load is greater than 50 kN (inelastic deformation). Figures 4 and 5 show the results of mathematical processing of signals from sensor 1 (see Figure 1b), obtained at 4 loading stages corresponding to the steps 18, 22, 34, 37 (see Figure 4). As follows from Figure 4, active generation of acoustic pulses is observed at these cycles. Sensors 1 and 2, close to the load source, respond to these processes first. The sequence of four frames in Figure 4 clearly demonstrates that at each of these loading stages there is an increase in the density of the parameter E (1) depending on time as the load increases, and a decrease as the load decreases.

18

22

1e-04

1e-05

70

80

1e-05

1e-06

60

60

1e-06

1e-07

F, kN

1e-07

E, a.u.

F, kN

50

E, a.u.

40

1e-08

1e-08

40

20

1e-09

1e-09

30

11850

11900

11950

12000

14200

14250

14300

14350

Time, s

Time, s

37

34

1e-04

140

1e-04

120

1e-05

120

1e-05

100

100

1e-06

80

1e-06

80

F, kN

F, kN

E, a.u.

E, a.u.

60

1e-07

1e-07

60

40

1e-08

1e-08

40

20

1e-09

1e-09

23000

23050

23100

21400

21450

21500

21550

Time, s

Time, s

Fig. 4. Change in load (green line) and distribution of parameter E (black dots) for acoustic signals in time intervals corresponding to four loading cycles (18, 22, 34, 37).

The 4 frames of Figure 5 show the distribution of acoustic pulses in the coordinates of the inverse velocity (3) – force on the jack (RA – F) for four loading stages (18, 22, 34, 37). The red circle on these graphs shows the average values of the signal parameter. These graphs show that the main increase in the number of acoustic signals at each