PSI - Issue 65

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

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stage occurs when the load exceeds the maximum force achieved in the previous stage. Thus, at stage 18, the maximum loading force is 73 kN, which is 3 kN more than at stage 17. In this case, the bulk of points corresponding to acoustic pulses are concentrated in the region from 70 to 73 kN. For stages 22, 34 and 37, the maximum force / force increment values are 90/8, 127/5 and 143/6, respectively, and the region of maximum signal concentration is more than 80, 120 and 130 kN, respectively. Taking this into account, we can conclude that the nature of the distribution of acoustic events and their density in the coordinates (RA – F) indicates the manifestation of the well known Kaiser effect described in the work of Holcomb (1993).

18

22

0.00 0.02 0.04 0.06 0.08 0.10

RA, s/V

RA, s/V

30 70 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 40 50 60

20

40

60

80

Force, kN

Force, kN

37

34

0.00 0.01 0.02 0.03 0.04 0.05

RA, s/V

RA, s/V

20 100 120 140 0.00 0.01 0.02 0.03 0.04 0.05 0.06 40 60 80

20

40

60

80

100 120

Force, kN

Force, kN

Fig. 5. Acoustic pulse distribution in (RA - Force) coordinates for 4 load cycles (18, 22, 34, 37).

The sequence of four frames in Figure 7 shows Wavelet images of the amplitudes of one acoustic pulse in coordinates (frequency f – time t ). The pulse was generated in the slab, at the location of the load, and the recording was carried out at the locations of the 4 sensors shown in Figure 1b. Comparison of the results presented in the images allows us to draw the following conclusions: the amplitude-frequency composition of the AE signal changes as the distance between the sensor and the AE source increases; the high-frequency component of the signal at a