Tadao Takigami

Numerical Analysis of Three-Dimensional Flexural Vibration of Railway Vehicle Car Body

An analytical method to investigate the three-dimensional (3D) flexural vibration of railway vehicle car bodies is presented in this article. In the method, a car body is modeled as a box-type structure consisting of plates and beams. The condition to connect components is satisfied by introducing artificial springs at their joints. The detailed analytical procedure is described. Some numerical calculations are carried out employing a commuter vehicle, which has a stainless steel car body, as an example. The numerical results are compared with the measured data to evaluate the validity of the model. Although the target vehicle has complicated mode shapes, it is shown that the analytical model can express such 3D vibration mode shapes successfully. It is also demonstrated that a good agreement is observed between the calculation results by the above method and the measured data for both stationary excitation and running test.

Reduction of Bending Vibration in Railway Vehicle Carbodies using Carbody-bogie Dynamic Interaction

This paper presents a theory to utilise the longitudinal vibration in bogies as a dynamic vibration absorber (DVA) to reduce the vertical bending vibration of railway vehicle carbodies in a simple and easy way. This study focuses upon the interaction between carbody vertical bending and bogie longitudinal motion, and the condition for tuning the natural frequency of the bogie motion to the target carbody vibration is derived theoretically using a very simple formula. Numerical and experimental studies are then outlined to validate the theory and formula, and the DVA effects are observed from both of them. The effectiveness of the method is also confirmed from a running test with a Shinkansen train on a commercial line.

Vibration suppression of scale model of railway carbody with piezoelectric elements : (A study focused on designing shunt circuits)

The goal of this study is to reduce the bending vibration of railway vehicles by applying a vibration suppression technique. The technique utilizes piezoelectric elements that are electrically shunted by an external circuit. This paper presents an investigation by using a scale model of a Shinkansen vehicle with a length of about 5m, mainly focused on implementation of shunt circuits. Small pieces of piezoelectric elements are bonded to its floor structure and electrically connected to a shunt circuit. The authors propose a new method to implement shunt circuits, a part of which is virtually realized. The circuits are designed for practical use under the condition of high voltage generated by the elements. Two types of shunt circuits are tested in this study. One is equivalent to an inductor and a resistor in series, and the other consists of a negative capacitor and a resistor. In actuality, the inductor and the negative capacitor are replaced by virtually realized impedance components. Results of excitation tests show that the circuits implemented based on the proposed method function as expected and bending vibration of the carbody can be reduced successfully.

Experimental Investigations on the Damping Effect Due to Passengers on Flexural Vibrations of Railway Vehicle Carbody and Basic Studies on the Mimicry of the Effect with Simple Substitutions

ABSTRACT The effect of passengers on a railway vehicle is usually considered as additional mass in designing a carbody. However, previous studies by means of stationary excitation tests or running tests using actual vehicles indicate that passengers behave not as mass but as damping. In this paper, the authors examined the passengers damping effect under controlled excitation conditions on a roller rig through a series of excitation tests using a commuter-type vehicle. Large and multi-modal reductions of flexural vibrations of the carbody were observed when passengers existed. Influences of the number of passengers, distributions and postures of passengers were investigated. The authors also tried to mimic the damping effect by passengers using flexible tanks filled with fluids. Three kinds of fluids which have different viscosities have been tested. As a result of the excitation tests, good vibration reduction effects were observed by applying those tanks, and it has been found that the flexible tanks filled with fluids bring about vibration reduction effect (including multi-modal reduction) which is equal to or rather better than the case of similar mass of passengers in the carbody; the difference of viscosity gave little affect on the damping abilities. From these measurement results, a possibility of realising effective damping devices against flexural vibrations of railway vehicle carbodies representing passengers damping effect, in a simple, economical and environmental friendly way, has been demonstrated.