Development of Flexible Liquid Damper

The “Flexible Liquid Damper” (FLD) is a new concept of a vibration control device. The damper is composed of only two parts, a flexible ball and liquid filling in the flexible ball. The damper design is simple, but the mechanism underlying its significant damping capacity has not been clarified. Two kinds of tests are conducted to investigate the characteristics of the damper in this study. One is the sinusoidal sweep test, while the other is the free decay test. First, several parameters of the damper are investigated, such as its size, material and the properties of the liquid itself. As a result, it is found that the case of around 50% volume is the most effective rather than the case where the ball is 100% filled with liquid. Moreover, other conditions have some effect, such as the wall thickness of the ball, and the liquid viscosity. Both the free vibration and the sinusoidal sweep tests show its great damping capacity. The damping effect obtained in free vibration tests is higher than that by the sinusoidal sweep tests. In some test cases, two dominant peaks are observed; the peaks only appear in the case of some combinations of the damper parameters. An attempt is made to analyze the damping mechanism using the general-purpose computational tool “ANSYS”, by creating an analytical model of the damper to simulate the test results. From the numerical results, it is found that the vibration control mechanism of this damper is mainly similar to the mechanism of the dynamic vibration absorber. However, the numerical results also show that the damper is not a simple dynamic vibration absorber and may include some other energy dissipation or energy transfer mechanism.