Sweeping tuneable vibration absorbers for low-mid frequencies vibration control

This paper presents a simulation study concerning the low-mid frequencies control of flexural vibration in a lightly damped thin plate, which is equipped with three sweeping tuneable vibration absorbers and is excited by a rain on the roof broad frequency band stationary disturbance. The sweeping tuneable vibration absorbers are semi-active mass-spring-dashpot systems whose stiffness and damping properties can be varied uniformly within given ranges. They are operated in such a way as their characteristic natural frequencies are continuously varied to control the response of flexural modes that resonate within given frequency bands. More specifically, in this study the three sweeping tuneable vibration absorbers are operated asynchronously, each within one of three sequential frequency bands comprised between 20 and 120, 120 and 220, 220 and 320. Hz. The flexural vibration control effects produced by the three sweeping tuneable vibration absorbers are compared to those produced by three classical tuneable vibration absorbers, each set to control the response of a specific flexural mode of the plate resonating in one of these three frequency bands. The study shows that the proposed sweeping tuneable vibration absorbers outperform the classical tuneable vibration absorbers and produce about 6, 5, 4. dB reduction of the plate overall flexural response in the three frequency bands of operation. Also, the study indicates that the sweeping tuneable vibration absorbers are robust to variations in the plate flexural response. For instance they still produce about 5.1, 5.3, 4.6. dB reductions of the flexural response in the three frequency bands of operation when the plate is tensioned such that the flexural natural frequencies are shifted up from about 40 percent, for the first resonance, to 7 percent, for the tenth resonance.