Dynamic Analysis Of Wheel/rail System Considering Track Stiffness Irregularity

Track stiffness is the key factor affecting track structure vibration and the transmission of dynamic characteristic, and it is the important factor influencing wheel/rail dynamic interaction and train running quality, governing the maintenance workload of the track. Modern railway transportation demands for high track regularity, which includes geometric regularity and stiffness regularity. The railway track is large-scale construction; track stiffness irregularity exists objectively along the line due to the change of the supporting structure. Compared with geometric irregularity, the work insight into track stiffness irregularity is little, and the analysis of its dynamic influence on the wheel/rail system lacks relatively too. On one hand, there has been not unified track stiffness irregularity PSD so far, people just consider geometric irregularity in simulation calculation, which will influence the precision of the simulation result inevitably; On the other hand, the influence of track stiffness irregularity on track structure is needed to be paid attention to, which is more significant especially at the transit section of two different track structure pattern.Based on the vehicle-track coupling large system, this thesis does the following work:(1) The domestic and abroad research overview on track stiffhess is discussed, and the exiting defect of the research is pointed out.(2) Track stiffness random irregularity model and simulation approach is provided for the first time. First of all, the experiment materials of track stiffness including parts and whole is investigated, and the statistics characteristic of track stiffness is summarized; Then, according to the existing statistics characteristic of track component stiffness, the random sample of track parts stiffness is simulated by numerical emulate which adopts Monte-carlo method; Finally, on the basis of the statistical sample of the track parts stiffness, the simulation approach of the total track stiffness is presented, and track stiffness random irregularity Sample varying with mileage is provided.(3) The computer program is worked out basing on the vehicle-track coupling dynamics theory and vehicle-track coupling dynamics model. The program considered the influence of the track stiffness random irregularity. It calculated the dynamics influence on the wheel/rail system due to voided sleepers, and researched the differences whether taking into account track random stiffness irregularity or not, and analyzed the dynamics characteristic of embankment- rigidity bed transit section, and presents the design principle of transition length.The result of study shows: the voided sleepers have great damage function on the track structure, the track random stiffness irregularity has very little influence on the steady of vehicle while much on track structure, which is the important cause of track distortion. The track stiffness irregularity will accelerate the development of track geometric irregularity if big track stiffness irregularity exits. At embankment- rigidity bed transit section, the deflection of the rail changes obviously if only considering track stiffness difference, while the dynamics action is very small. There will be large dynamics action if considering track stiffness variety and asymmetrical settlement of foundation simultaneously, which has remarkable influence on track structure and the steady of vehicle, and the influence becomes greater with increasing of speed. The length of transit section should make the acceleration of vehicle as chief index.