Effect of Track Stiffness on Frequency Response of Vehicle-track Coupling System

Research purposes: Track stiffness is an important parameter for the design and maintenance of railway track. However,the frequency-domain influence of track stiffness on the vehicle-track coupling system is still not clear. Based on the theories of vehicle-track coupling system dynamics,taking the existing speed-increase line as an example,this paper explores the frequency-domain influence of track stiffness on the vehicle-track coupling system.Research conclusions:The influence of track stiffness on the vehicle and bogie is little and it influences the wheel set and the track structure a lot. With the increase of track stiffness,the vibration response of vehicle-track coupling system goes stronger obviously in the medium-high frequency band of 100 Hz above,but the vibration response in the low and medium frequency band of 27 ~ 70 Hz gets a little weaker and it shows nearly no influence on the vibration response in the low frequency band of 27 Hz below. As the stiffness of fastener system increases,the maximum values of wheel-rail force spectrum,the wheel set acceleration spectrum and the rail vibration acceleration spectrum all increase considerably and the vibration frequency shows a tendency to occur a frequency shift towards high frequency band. The similar rule can be found in the research of the stiffness of ballast bed. Overall,in the frequency domain,the stiffness of fastener influences the vibration response of vehicle-track system greatly while the stiffness of ballast bed affects thevibration response of vehicle-track system relatively weaker,so deteriorative fasteners should be replaced in time while the maintenance cycle of ballast bed can be extended appropriately. The research can provide a good guidance for the optimization design of track structure and the track maintenance.