Vertical Vibration Of The Train - Track - Subgrade System

With the overall development of high-speed rails, the trains have been gradually speeding up and the dynamic interaction among the trains, tracks and subgrades is becoming greater. Therefore, the problem of Train-Track-Subgrade coupling dynamics is drawing more and more academic attention. Based on the general narration of the development and current status of the domestic and international study on the relevant problems, this thesis aims to carry out a deeper research on the problem of vertical vibration in Train-Track-Subgrade time-varying system. Its main work and study contents are as follows,(1) The paper analyzes the displacement and variation principle of discrete-system dynamics, and it expounds that applying this principle in dynamic modeling can greatly simplify the modeling process and this is very helpful in establishing the multi-degree freedom systemic dynamic equation.(2) With the Train-Track-Subgrade system regarded as a whole to be divided into units, basing on this displacement and variation principle, the paper respectively forms vabriation equations for the part over the springs of vehicles, mobile connection interface and the track-subgade structure, and then according to the "Right Position" role, it forms the whole equation for the Train-Track-Subgrade coupling system by blending the three equations. This method simplifies modeling process and makes it convenient for the computers to calculate.(3) In this paper, the Train-Track-Subgrade vertical vibrating response calculating procedure is programmed with the use of Matlab software as a developing platform, and the use of wilson-θstep by step integrating method,. By examples, the paper makes an analysis of the Train-Track-Subgrade vertical vibrating response. It also verifies that this systemic modeling method based on mobile connective units is feasible.(4) The paper analyzes that five-time modified Hermitian cubic interpolated shape function is better than the traditional Hermitian function in satisfying the continual characteristics of the nodes of the stiffness matrix in this system, and it also analyzes calculation of the wheel-rail contact force for high-speed rails.