PSI - Issue 65

I. Shardakov et al. / Procedia Structural Integrity 65 (2024) 233–240 239 I. Shardakov, R. Tsvetkov, I. Glot, A. Shestakov, G. Gusev, V. Yepin / Structural Integrity Procedia 00 (2024) 000–000 7

distance of more than 2 meters practically disappears and only the low-frequency component remains; as the distance increases, significant dispersion of the wave signal occurs.

Fig. 6. Wavelet image of one AE signal in coordinates (frequency – time) obtained for four sensors located at different distances from the AE source.

Table 1 presents the parameters of the AE signal recorded by four sensors at different distances from the source. The wavelet images of this signal are shown in Figure 6.

Table 1. Parameters of signal

Parameter

Sensor1 (0.2 m)

Sensor1 2 (0.2m)

Sensor1 3 (1.8m)

Sensor1 (3.8m)

Peak to Peak , V

1.45

1.18

0.091 2.8E-7 1.556 73.5E-4

0.0120 6.3E-9

E, a.u.

2.5E-5 1.042 1.5E-4 0.096

3.2E-5 1.061 6.6E-4 0.277

T start, ms

2.330 0.738 0.679

RA, s/V

WI, dimensionless

0.115

4. Conclusions

The paper presents the results of an experiment using the AE method to record the inelastic deformation of elements of a large-scale model reinforced concrete structure under local force loading. The experiment was carried out on a special experimental stand that allows you to study deformation processes in building and engineering structures with characteristic linear dimensions of 10 m. The loading had a cyclic character “load – full unloading”. At each subsequent step the maximum value of the load was greater than the previous one, and the incremental was not more than 10 kN. 38 cycles were realized. The load at the last stages reached 150 kN. The dependence of the number of acoustic pulses on the magnitude of the load, obtained by the sensors at various characteristic stages of cyclic loading, clearly records the range of loads less than 50 kN, where there are no acoustic pulses (the stage of elastic deformation) and the range of more than 50 kN, where a rapid increase in pulses occurs (the stage of inelastic deformation). Graphs of acoustic pulse distribution in coordinates (RA – F) (inverse velocity – force) for typical load cycles associated with high levels of AE signal generation, are obtained. The nature of the distribution of acoustic events and their density in coordinates (RA – F) indicate the manifestation of the well-known Kaiser effect. Based on the results of mathematical processing of acoustic signals using Wavelet analysis, the following was established