PSI - Issue 84

1060 Gian Felice Giaccu et al. / Procedia Structural Integrity 84 (2026) 1055–1062 The gyricity Ω is calculated as the product of the polar moment of inertia Ω, and the angular velocity . Fig. 4(b) shows Ω as a function of the input voltage, noting that the current drawn by the circuit differs between the two models. 3.3. Experimental Flutter Observations with Inactive Gyroscope (Uncontrolled Case) The onset of flutter is identified by gradually increasing the wind tunnel speed until the deck exhibits divergent pitching motion , with amplitudes exceeding 15° considered to be sufficiently large and, therefore, designated empirically as the onset of flutter. In the uncontrolled case (gyroscope off), the critical flutter velocity is experimentally estimated as cr ≈13.00 m/s, closely matching the numerical prediction of cr =13.95 m/susing the numerical model (Giaccu and Caracoglia, 2021; Giaccu and Caracoglia, 2025) with =0 rad/s (Fig. 5). As shown in Fig. 5(b), diverges sharply beyond this speed, confirming flutter onset and providing validation for the numerical model.

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(c) Fig. 5. Time histories in the uncontrolled case ( =0 rad/s): (a) mean wind speed , (b) deck pitch angle , (c) gyroscope angular velocity . 3.4. Experimental Flutter Observations with active Gyroscope (Model 1) Results for Section Model 1 are shown in Fig. 6. At a wind speed above the uncontrolled critical flutter velocity, the gyroscopic device was progressively activated by adjusting . The pitch angle remained below a few degrees once steady state was reached (~50 s). Stabilization became noticeable at =400 rad/s and nearly complete at = 950 rad/s. Reducing (below 250–350 rad/s) caused a gradual increase in , demonstrating the device’s ability to rapidly control deck vibrations.