Comparison And Analysis On The Types Of The High-speed Railway Transition Curves And Vehicle Dynamic Behavior

As the train speed increases, to ensure the vehicle runs safely and stably, higher requirements on track geometry should be met. Transition curve are normally inserted between straight line and circular curve in order to make the train passes smoothly from straight to circular curve or from circular curve to straight. The studies on the transition curves have been carried out for about 100 years. However, there still much disputes on the selection of transition curve shape, so it's the high time to analysis the operative performance of railway transition curves.The equation of transition curve determines its shape, the performances relate to dynamic can be obtained by use of it. A model equation for determining its equations by the aid of boundary conditions of transition curve is presented. According to the boundary conditions of transition curve varies comon transition curves functions and the performances relate to dynamic are obtained. And the relations among performances are illustrated in figures by use of the MATLAB software.The carbody acceleration and lateral change of it play an important role in determining the transition curve parameters. Based on the vehicle movement dynamics, the motions with positive or negative acceleration are taken into account to deduce the equation of lateral change of the carbody acceleration. According to the selected parameters of transition curves and circles, the carbody acceleration and lateral changes of it of the eleven transition curves of railway are calculated and compared with each other in theory by use of the MATLAB, according to the equations of the carbody acceleration and the lateral changes of it.By using the MATLAB, the German high speed track spectrum is changed into simulation sample in a time domain of railway track irregularity. According to the parameters of high-speed vehicle, a high-speed passenger car modle which has 93 degrees of freedom is established by adopting the MSC.ADAMS/Rail that is rail/vehicle system dynamics numerial software. The shapes of trantion curves of railway are set by approach of irregularity. the carbody acceleration and lateral changes of it of the eleven transition curves of railway are simulated in ten-different motion models that there are five models which take the railway track irregularity into account and the rest five models not, and compared with the results in theory.The results showed that the deduced equation of lateral change of the carbody acceleration which considers motion through transition curve with positive or negative acceleration can be used for comparing and choosing transition curves. Discontinuity in the form of a jump of the lateral change of the carbody acceleration has greater effect on the passengers comfort than the maximum when the lengths of transition curves are the same. The lateral change of the carbody acceleration of cubic parabola transition curve has discontinuities at four joints, while of the transition curves with curvilinear superelevation ramp do not have any discontinuity in the form of a jump, so the transition curves with curvilinear superelevation ramp is superior to the cubic parabola curve in improving passengers comfort when taken into account the motions with positive or negative acceleration, it is proposed that the transition curves with curvilinear superelevation ramp should be used when the length of transition curve is constrained by surroundings, especially at both ends of the station area where the vehicle motion with acceleration. The railway track irregularity has a bad effect on the safety and running stability of train, and has worse effect than the maximums of the carbody acceleration and lateral change of it, so it must to strictly control the high speed railway track ride.