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

246

6

a

b

c

Fig. 5. Generation of AC signals when loading a reinforced beam (sensor on concrete): (a) – classification of AE signals by mode, (b) – total count of AC signals of mode 1, (c) – total count of AC signals of mode 2. Blue – high frequency signals, green – low frequency signals

The sensor installed on the composite coating recorded a completely different character of the signals. AE signal distribution map in Fig. 6a shows that low-frequency signals prevail at this sensor. Signals generated by opening cracks begin to actively increase at stages correlated with the formation of the first cracks in concrete (13000s). The number of signals generated by shear cracks gradually increases at loading intervals associated with the appearance of the first cracks and the development of cracks in concrete (14000–28000 s). At the final stages of loading there is a sharp increase in the number of signals (30000s).

a

b

c

Fig. 6. Generation of AC signals when loading a reinforced beam (sensor on composite): (a) – classification of AE signals by mode, (b) – total count of AC signals of mode 1, (c) – total count of AC signals of mode 2. Blue - high frequency signals, green - low frequency signals

4.

Conclusion.

An experimental study of deformation processes in a reinforced concrete beam under increasing bending load made it possible to identify the features of AE processes occurring in concrete and composites. In general, the patterns recorded by AE sensors installed on the concrete surface of beams with and without reinforcing composite layer coincide. Maximum AE activity occurs at the stage of the first cracks appearing in concrete. The bulk of the pulses are associated with the appearance of opening cracks. Acoustic emission on a composite plate has completely different patterns. Sources of high frequency signals are identified primarily as opening cracks. The emission of these signals is activated at the stages following the appearance of visible cracks in the concrete, and at the final stages of loading before the complete destruction of the beam. Low frequency signals are associated with both opening and shear cracks. The formation of type 1 cracks in the composite is activated at the stages following the appearance of visible cracks in concrete, and type 2 – at the