PSI - Issue 52

Alessandro De Luca et al. / Procedia Structural Integrity 52 (2024) 424–429 Alessandro De Luca / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 2. Experimental facility

Figure 3 shows the load vs. time curves used for the tests. It is possible to note that the load is kept constant for 15 minutes to permit the excitation and the acquisition of the signals at different frequencies.

Figure 3. Force vs. time curves

The damage was then simulated by applying pressure to a circular metal element with a diameter of 20 mm using a mechanical vice. Considering a Cartesian reference system with origin at the vertex closest to sensor 2 (Figure 4), the position of the damage centre is (109.5 mm; 170 mm). GW excitation and acquisition phases were carried out using two TiePies connected in parallel. The input signal is a tone burst with a five-cycle Hanning window. Frequencies were varied with a step of 50kHz in the range from 100 to 300 kHz. This range was chosen to avoid generating wave modes of higher order so to excite only the 0-order modes S 0 and A 0 . However, for the sake of brevity, the analysis of the results herein presented focuses on the central frequency of 200 kHz.