Vertical Vibration Analysis of Vehicle-Track-Subgrade Coupled System in High Speed Railway with Dynamic Flexibility Method

A high speed train-track-subgrade vertical coupled dynamic model is developed in frequency domain. In this model, coupling effects between vehicle and track and between track and subgrade are considered. Full vehicle is represented by a rigid body model of a body, two bogies, and four wheelsets connected to each other with springs and dampers. Track and subgrade system are considered as a multilayer beam model connected to each other with springs and damping element. The receptances of track and subgrade system are discussed and receptance contribution of the wheel/rail coupling system are investigated. Combined with the pseudo-excitation method, a solution of the random dynamic response is presented. The random vibration response and transfer characteristics of ballastless track and subgrade system are obtained under track random irregularity when a high speed vehicle runs through. The displacement receptances of rail are higher than the track slab and the subgrade in 10~5000Hz, and that of track slab is more than the subgrade above 30Hz; Frequency ranges of energy distribution of rail vibration are more wide than track slab and subgrade, whereas the vibrations of track slab and subgrade are mainly focused blow 43Hz.