Abstract
It has been shown that passengers have large reduction effect against elastic vibration of railway vehicle car body. That effect is considered due to viscoelastic motion and multi-directional motion of human body. This study focuses on the latter one and aiming to develop a new vibration reduction device to mimic the multi-directional motion of passenger. In this paper, an experimented multi-directional dynamic vibration absorber (called MDDVA in this report) is developed. The MDDVA consist of a resiliently supported metal ball and elastic balls to support the metal ball bottled in a rigid cylindrical vessel. The metal 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 test using a scale model of railway vehicle is conducted. As a result, 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 railway vehicle are constructed to verify the mechanism of multi-modal vibration reduction. It is confirmed that the multi-directional motion of the metal ball produces the multi-modal vibration reduction effect by FEM analysis.
