Multimodal reduction of flexural vibration in railway vehicle carbody using elastic torus

This work presents a study to reduce flexural vibrations which have large impact on the ride quality of a rail vehicle by applying some elastic bodies as dynamic vibration absorbers (DVAs). A donut-shape (called "torus" in this study) is proposed as the elastic body considering practical application. A torus dedicated as a DVA for rail vehicles is designed and manufactured actually. The developed torus is made of rubber and usable with water filled inside with internal pressure up to 20 kPa. The mass of the torus in case filled with water with 10 kPa is 12 kg/piece, and it has a natural frequency around 10.6 Hz. Numerical studies using Nastran for a Shinkansen vehicle carbody are carried out and it is shown that DVA effects are expected when 20 tori are applied on the floor of the carbody. Finally, a series of stationary vibration tests for a Shinkansen-type test vehicle with aluminum-alloy carbody was conducted. Large and multimodal vibration reduction effect has been observed against flexural vibrations of the carbody successfully. Influence on the vibration reduction effect by the difference of the number of applied tori and the distribution on the floor are investigated experimentally.