PSI - Issue 65

I. Shardakov et al. / Procedia Structural Integrity 65 (2024) 241–247 I. Shardakov, I. Glot, A. Bykov, I. Panteleev A. Shestakov / Structural Integrity Procedia 00 (2024) 000–000

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Results.

AE signals recorded at successive stages of sample loading were processed using Fourier analysis. Filtering the signals made it possible to identify 2 dominant frequency intervals in which AE signals are significant. The low frequency interval was 20–200 kHz, and the high-frequency one was 200–1000 kHz. Further, the features of AE characteristic in these two frequency ranges were analyzed. The patterns of changes in the number of AE signals at successive stages of loading were studied for beams with and without external reinforcement. The process of deformation and destruction of beams is accompanied by intense acoustic emission. Figure 3 shows the total count of AE signals recorded in the experiment at each loading and unloading step, obtained for the conventional beam and the beam with CFRP canvas. A local increase in AE activity corresponds to the 15th (for a conventional beam) and 16th (for a reinforced beam) loading stages, at which the first macrocracks were recorded. At unloading stages 15-20, an increase in the number of AE signals is also recorded, but it is an order of magnitude lower than during loading. This effect may be associated with the redistribution of stresses during inelastic deformation and the formation of macrocracks. Comparison of graphs Fig. 3a and 3b allows us to conclude that the AE signals recorded on the concrete surface of both beams are comparable both in level and distribution. At the same time, the intensity of high-frequency and low-frequency signals differs slightly. This allows us to assume that these high-frequency signals can be correlated mainly with the processes of inelastic deformation occurring in concrete. a

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Fig. 3. Total count of AE signals at each step of loading (left) and unloading (right): (a) – conventional beam, (b) – reinforced beam, sensor on concrete (c) – reinforced beam, sensor on a composite plate