2018 年 84 巻 866 号 p. 18-00112
It has been shown that passengers have large reduction effect on the elastic vibration of a railway vehicle car body. That effect is considered due to the viscoelastic motion and multi-directional motion of a human body. This study focuses on the latter one and aims to develop a new vibration reduction device to mimic the multi-directional motion of passengers. In this paper, an experimented multi-directional dynamic vibration absorber (called MDDVA in this report) is developed. The MDDVA consists of a steel ball supported resiliently by elastic balls bottled in a rigid cylindrical vessel. The steel ball can vibrate multi-directionally in the vessel and is expected to work as a MDDVA. In addition, the natural frequency of the MDDVA can be changed by pressing the elastic balls from the top. To evaluate the effectiveness of the MDDVA, excitation tests by means of a scale model of a railway vehicle is conducted. As a result, the MDDVA can reduce the elastic vibration by adjusting the natural frequency of MDDVA to that of the scale model, and multi-modal vibration reduction effect is successfully observed. And then, FEM models of the MDDVA and a scale model of the railway vehicle are constructed to verify the mechanism of the multi-modal vibration reduction. As a result of the FEM analysis, it is confirmed that the multi-directional motion of the steel ball produces the multi-modal vibration reduction effect.
