Dynamic Vibration Absorber (DVA) Using Combined Piecewise and Magnetic Stiffness Mechanism

Linear dynamic vibration absorber (DVA) efficiently suppresses the structural vibration within the 3 dB amplitude frequency bandwidth. Beyond this bandwidth, it may not be effective in suppressing the vibration. In fact, if not properly tuned, it may increase the vibration of the structure. This study examines a DVA mechanism incorporating a unique piecewise and magnetic stiffness combination. By integrating these two types of stiffness, the DVA operates in nonlinear modes, improving its ability to dampen vibrations over a wider frequency range. The positioning of limit blocks and the gap between magnets allows precise control over the level of nonlinearity for each mode, namely, hardening, softening and combined modes. Quasi-static measurements were conducted to analyse the static characteristics of the device for each mode. Dynamic measurements were conducted to analyse the device's dynamic performance in deflection-frequency characteristics, providing insights into the device's response across a frequency range (10 Hz to 50 Hz) for each mode. This evaluation helped assess the proposed mechanism's ability as a DVA to mitigate vibrations with varying frequencies. The measurement results from the three modes were compared. While hardening and softening modes proved to be able to widen the bandwidth, the combined mode was the most effective one in widening the bandwidth as its operation covers both operating regions of softening and hardening modes. The decrease in the multi-stable solution frequency region ensures that the NDVA operates with a larger amplitude in the vibration suppression region more favourably.