PSI - Issue 44

Hasan Borke Birgin et al. / Structural Integrity Procedia 00 (2022) 000–000

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Hasan Borke Birgin et al. / Procedia Structural Integrity 44 (2023) 1624–1631

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Fig. 5. Dynamic test results of the smart material beam with hammer hits located on the center of the beam, raw reading, and frequency-time analysis for the (a) segment between the electrodes 1-2, (b) segment between the electrodes 2-3, (c) segment between the electrodes 3-4.

The test case shown in Fig. 5. differs from the previous one by the placement of the hammer hits. The obtained results are very similar; the hammer hits are clearly visible for the initial two segments (Figs. 5(a) and (b)), remarking that now the dynamic response generated by hammer impacts is more uniform with respect to the previous test. The results from the third segment (Fig. 5(c)) has high noise-to-signal ratio, and the hits are not clear. The time-frequency analysis shows that the beam vibrated with a frequency around 65 Hz. The beam with embedded sensors generated results similar to the beam made of smart concrete, concerning the dynamic tests. The results are presented in Fig. 6. Compared to the previous results, dynamic response generated by embedded sensors looks weaker in terms of magnitude. The reason for this behavior could be the interaction quality between the embedded sensors and the beam. According to the resistance time histories, the noise-to-signal ratio is high for all of the embedded sensors. The hammer hit position sequence is applied on the sections 1-2-3 (Fig. 3(b)). Therefore, the dynamic response amplitudes coincide with the given hit the sequence. The polarization drift of sensors 1 and 3 are stronger than the one of sensor 2. The negative effects of high noise to-signal ratio and the drift is evident with the frequency-time analysis since the generated vibration frequencies are more distinctive in the response of sensor 2 (Fig. 6(b)). The observed vibration frequency for the beam with embedded sensors is observed to be around 80 Hz. This value is obtained through all three sensors in different test instances.