PSI - Issue 69

Diego Scaccabarozzi et al. / Procedia Structural Integrity 69 (2025) 80–88

83

Fig. 2. Modal analysis – first vibration mode in free constraint condition.

The numerical simulation revealed a first bending natural frequency at 5112 Hz, thus providing an excitation range between 5 kHz and 6 kHz. The measurement setup and chain are illustrated in Fig. 3. A Laser Doppler Vibrometer (LDV – Polytec OFV 505) was used for a noncontact vibration measurement. Additionally, a BSWA MA 201 microphone with a sensitivity of 51.79 mV/Pa measured the sound pressure generated from the loudspeaker. Furthermore, to monitor ambient temperature and ensure consistency during tests, a thermocouple measuring the ambient temperature was added. All signals were acquired using an NI 9234 data acquisition board. The frequency response function was computed by averaging the data from at least ten frequency sweeps. The samples were mounted on elastic cords positioned at the nodal lines.

Fig. 3. The experimental setup. (Left) testing setup scheme, (right) view of the sample over the suspension and LDV spot.

Each sample underwent at least ten subsequent sweep sine cycles, each lasting 50 seconds. To further confirm the accuracy of the results and consider the effect of the positioning on the elastic cords, the tests were repeated three