2．Reduction method of car body elastic vibration using high-damping elastic support for under-floor equipment

A new method to reduce car body vibration was developed with high performance damping material to provide elastic support to under-floor equipment. The present method simply modifies the support mechanism for under-floor equipment, increasing mass only negligibly.
This method simultaneously reduce vehicle elastic vibration and transmission of vibration from the equipment.

A new method was developed providing elastic support to under-floor equipment with high performance damping materials to reduce vehicle elastic vibration, which has a significant influence on ride comfort, and at the same time suppresses transmission of equipment vibration to the vehicle. A prototype of high-damping elastic support was developed employing hydraulic mount technology used in the automobile and construction equipment industries as a base. In order to test the performance of the high-damping elastic support, two sets of dummy under-floor equipments were installed into a commuter type test vehiclel One of the equipments had an exciter to simulate vibration generation of under-floor equipments, and the other was just dead weight. Then the test vehiclewas subjected to vibration tests at RTRI’s rolling stock testing plant(Fig.1).

Results of the trials validated the utility of the new method showing that the developed high-damping elastic support simultaneously reduced multiple mode of elastic vibration of car body and also had an isolating effect on equipment vibration (Fig.2), and that there was no increase in under-floor equipment vibration itself (Fig.3), inter alia. This vehicle elastic vibration suppression measure is maintenance free, lightweight and easy to use and can be adapted to a variety of different vehicles.

Fig.1 Test vehicle under excitation test at the rolling stock testing plant, and schematic illustration
of the application of the high-damping elastic support (The high-damping elastic support in this
set of tests was inserted in the space under frame carrying the dummy piece of equipment).
Fig.2 Effect of applying the high-damping elastic support
(Under-floor acceleration PSD under the central window of a vehicle,
Lt in the legend is level of vertical ride comfort)
Fig.3 RMS (root mean square) values of acceleration of mobile element on dummy equipment