Dynamics Analysis Of Four-Axes Track Loading Vehicle

With the rapid development of railway, track engineering as the foundation of railway operation, is studied by line integral research method with entity engineering for research object transformed from previous theory research method. Track loading vehicle become one indispensable tool. The domestic and foreign public literatures introduce mainly some structures and the loading performances of track loading vehicle, but dynamics analysis of track loading vehicle is not published. So it has great significance to analyze the dynamic performance of track loading vehicle. This article will analyze four axis track loading vehicle through two methods both the theoretical analysis and the dynamics simulation, and validate the feasibility of parameters scheme of four axis track loading vehicle.Firstly, from this safety angle of wheel unloading ratio, this article analyzes the influence law of the curve ultra-high,vertical load and horizontal load to static wheel unloading ratio. The variations of wheel unloading ratio caused by various factors are proportional to them. Moreover the variations of wheel unloading ratio caused by various factors are inversely proportional to themselves. Considering various influences, minimum safety limit axle load is calculated in different conditions with safety limit overturning coefficient 0.8.Then, from stability angle, this article analyzes the linear stability of both hang operation and loading devices of four axis track loading vehicle and the influences of vertical loads to the linear stability by the simplifying mathematical model. In addition, natural frequency of ups and downs,yawing of car and bogie are theoretically calculated by simplified formula, and are closed to the simulation results.Finally by using the multibody dynamics software, the dynamics simulation model is build of four axis track loading vehicle in different conditions, and the stability,stationary and curve are calculated and analyzed. Track loading vehicle has linear and nonlinear critical speeds which can meet the operation requirements, but the nonlinear stability is worst by vertical and horizontal load. Besides the max of wheel unloading ratio is more than our country's limited while loading the vertical and horizontal load at 50km/h～70km/h speed, track loading vehicle has good linear steadiness in other conditions. When four axis track loading vehicle negotiates curve, it can safely negotiate R300m and R1100m curves which are calculated by vertical load 125kN, and wheel unloading ratio at some speed by vertical load and horizontal load to out rail exceed our country's limited, but is smaller than America's limited.Analyzing the calculation result, it's found that wheel unloading ratio is the key factor to safely operate track loading vehicle. In the design and application process, we should take measures to reduce wheel unloading ratio.