Liquid Dynamic Absorbers for Ropeway Carriers and Ships

Abstract

Abstract After Matsuhisa proved that the wind-induced swing of ropeway carriers could be reduced by dynamic absorbers in 1993, many absorbers have been installed in ropeway carriers. In the actual use of dynamic absorbers composed of a steel moving mass on a arc-shaped track, the tunings of natural frequency and damping coefficient are not easy. Liquid-type dynamic vibration absorbers have advantages of ease of tuning the natural frequency and the damping coefficient. In this study, dynamic absorbers composed of liquid (water or viscous liquid) in V-shaped or U-shaped pipes were investigated. The natural frequency can be easily adjusted by the amount of water. The damping coefficient can be adjusted by nozzles at the terminals of pipe, an orifice or a net in liquid and by the viscosity of liquid. The reduction of rolling of gondola lifts, ships and cable suspension bridges by the liquid dynamic absorbers were investigated theoretically. The formula to predict the effectiveness of the absorber was derived. The relationship between the effectiveness of the absorber and its location and shape was discussed. The experimental investigations on the swing of pendulum, the roll of ships and flutter of cable suspension bridges were carried out by means of small models. It was found that the absorbers could reduce the rolling very well and it would be possible to install to the real gondolas, ships and cable suspension bridges.