Study On Random Vibration Analysis Of High Speed Vehicle Track Coupling System And Evaluation Method Of Track Irregularity

As the main excitation source of the vibration of vehicle-track coupling system, the track irregularity influences significantly the ride stability, quality and even safety of the train, making it the major factor limiting the train speed. As the train speed increases, much better track geometry condition is expected. Therefore, the researches on evaluation methods of the track geometry and the relationship between the track irregularity and the vibration of vehicle-track coupling system are of great theoretical and practical significance. Based on the existing domestic and overseas relative theories, the research on the random vibration of vehicle-track coupling system and the evaluation methods of the track geometry was carried out. The main research work includes the following areas:1. Analysis of random vibration of infinite periodic structureThe infinite periodic structure is made of uniform substructures connected with each other periodically and endlessly. Track structure is a kind of typical infinite periodic structure. The wave spectrum element method was applied into the analysis of random vibration of the infinite periodic structure. Taking track structure as an example, the wave spectrum-symplectic kinematic equation of infinite periodic structure was established. This method focuses on the load-carrying substructure, builds the dynamic stiffness matrix by the wave spectrum element method and solves the wave propagation in and between the substructures with the symplectic method. This method keeps the property of small number of DOFs due to the use of symplectic method and also owns the advantage of high accuracy solving high-frequency vibration because of the use of the wave spectrum element method, which provides a new thinking for the analysis of the random vibration of track structure.2. Establishment and solution for the vehicle-track coupling dynamic modelBased on the theories of vehicle-track coupling dynamics, the random vibration model of vehicle-ballasted/CRTSII non-ballasted track coupling system was established. In this model, the vehicle system was treated as muti-body system and its kinematic equation was built by the Hamilton principle. The ballasted track was regarded as three layers point supported model and its kinematic equation was built by the use of symplectic method and wave spectrum element method. The CRTSII non-ballasted track was also treated as three layers structure, in which the rail was point supported and the track slab and base slab are all continuous supported. The kinematic equation of vehicle-track coupling system was organized according to the linear simplified wheel-rail interaction relationship. The frequency-domain response of the coupling system was acquired by the frequency analysis method and the validity of the model was verified.3. Random vibration analysis of the vehicle-track coupling systemOn account of the vehicle-track coupling dynamic model above, the effects of track irregularities like layout, crosslevel, warp and track gauge on the coupling system were analyzed. The amplitude-versus-frequency curves involving the track irregularities and the vibration responses of vehicle-ballasted track/CRTSII non-ballasted track coupling system were analyzed and by which the sensitive waves of track irregularities were calculated. Besides, the influences of train speed, type of train and track stiffness on the amplitude-versus-frequency curves involving the track irregularities and the vibration responses of vehicle-track coupling system were further discussed.4. Evaluation methods for the track geometry based on dynamicsAccording to the relationship between the track irregularities and the vibration responses of vehicle-track coupling system, wavelength weight coefficients were introduced into the track irregularities and a new evaluation index for track irregularity was put forward, called TWQI (Track Weight Quality Index). With different series of wavelength weight coefficients, the TWQI could be classified into two types:TWQI-C for train's running comfort and TWQI-S for train's running safety, respectively. In the dissertation, taking test data samples from Chang-Jiu inter-city express as an example, the reasonability of TWQI was verified, and the distribution characteristics and deterioration rules of TWQI were further researched, which provides much reference for the application of TWQI.5. Development of the assessment software for track irregularitiesAn assessment software for track irregularities was developed using MATLAB. The software has functions like dynamics calculation, weighted analysis and evaluation for track irregularities. The wavelength weight coefficients could be acquired through the input of parameters of vehicle system, track structure, train speed and actual measurement data of track geometry. Then the wavelength weighted track irregularities were obtained. At last, single index and aggregative indicator of TWQI could be figured out.