DEICON’s patented, semi-actively controlled, ‘air suspended tuned mass damper’ (TMD) uses one/multiple air spring(s) as both the restoring (resilient) and the energy dissipating (damping) elements. Feedback control is used to adjust the stiffness and damping of the air spring(s). The schematic of a tuned mass damper installed on a structure is shown in Figure 1. These TMDs can readily be fine-tuned and re-tuned, via software, without changing any hardware.
Figure 2 shows images of a 1500 lb air suspended tuned mass damper with horizontal pendulum configuration, being tested to demonstrate the effectiveness of the semiactive control schemes in adjusting its damping and stiffness.
Figure 3 shows the impulse responses of the TMD mass with the semi-active damping control scheme off (blue trace) and on (red trace). The comparison of the two traces clearly shows the effectiveness of DEICON’s semi-active damping technology. The extent of damping in the TMD can readily be changed via software. The two traces in Figure 4 also show impulse responses of the TMD mass with the stiffness control off (blue trace) and on (red trace).
Clear from Figure 4, the natural frequency of the air suspended tuned mass damper has increased using the stiffness control strategy. In general, this control scheme can increase the TMD stiffness 3-4 folds, resulting in a change in tuning frequency by a factor of up to two. As in damping, the extent of stiffness (and thus the tuning frequency) in DEICON’s air suspended TMD can readily be changed via software. With this feature, these TMDs are capable of self-tuning themselves.