| Summary: | A generalized railway vehicle model is built to study the coupled vibrations between a flexible car body (CB) and the equipment suspended beneath it by taking the complex suspension characteristics of the equipment into consideration. Associated theories for the determination of the suspension parameters for CB suspended equipment are summarized systematically, including the vibration isolation methods and the dynamic vibration absorber (DVA) theories for both undamped and damped cases. The equipment is then grouped into four categories by weight, location, and the excitation that it is subjected to. A general principle for the determination of the suspension parameters is proposed for better vibration isolation effects concerning bogie hunting, the elastic modes of the CB and its excitations. Analysis based on DVA theory shows that 1) siting equipment heavier than 2 t near the CB center can reduce the structural vibrations of the CB considerably, 2) siting medium-weight equipment near one end of the CB is good for absorbing the vibrations resulting from bogie hunting, and 3) a rigid connection is suggested for light equipment. Furthermore, on-track field tests of a high speed train confirmed that the heavy equipment vibrated violently upon absorbing some of the CB vibration energy resulting from bogie hunting. However, solid proof of the vertical bending of the CB was not obtained yet because it was sufficiently damped and is not the first natural mode of a modern aluminum-alloy CB. Further research on the lateral flexibility of the CB and its coupled vibrations with the heavy equipment mounted near its center are in need.
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