Research On Calculation Method Of The Whole Process Of Railway Train Wheel-jumping Considering The Wheel-rail Impact

Wheel-jumping phenomenon of railway vehicles will directly threaten the driving safety.The research on the mechanism of wheel-jumping is very complicated,and the calculation of the whole process of wheel-jumping is the key to revealing its mechanism.Therefore,the research of this thesis has important theoretical value and engineering significance.In this thesis,the whole process of wheel-jumping caused by vertical inducements is studied.According to the characteristics of the vertical wheel-rail interaction force and the vertical relative displacement of the wheel and rail,the whole process of the wheel-jumping is divided into the normal wheel-rail close contact stage,the wheel-rail separation stage,the wheel-rail impact stage and the stage of wheel-rail contact again.The vehicle-track coupling dynamics model considering the wheel-rail impact is established,and the cross iterative algorithm is used to calculate and analyze the vehicle-track system under the conditions of single harmonic,compound irregularity,failure of the cushion and rail fastener,and failure of the support under the sleeper.The influence law of wheel-rail dynamic response,vehicle wheel-jumping and train operation safety are studied.The main research contents and conclusions are as follows:（1）Summarize the domestic and foreign research on the problem of wheel-jumping,analyze and summarize the models,calculation methods and aspects that can be deeply discussed in the vehicle wheel-jumping research,and find out that this thesis can be studied in depth,model rationalization,computational method innovation and aspects of optimization.（2）A multi-rigid body dynamic model composed of car body,bogie and wheelset and a high-speed ballasted track dynamic model including rail-sleeper-ballast-subgrade components were established,and the vertical interaction force between the wheel and rail was used as a link to connect the two sub-systems.The system uses a cross iterative algorithm to calculate the vibration response of the two subsystems.This calculation method can effectively avoid the situation that the degree of freedom of the vehicle-track overall system matrix is changed due to the combination of single or multiple wheel-jumping,which is beneficial to programming and subsequent calculations.（3）The simplified multi-objective optimization algorithm is used to calculate and analyze the wheel-rail impact stage.When the wheel and rail are separated,and the wheel falls on the rail again,the displacement compatibility is satisfied,but there will be a speed difference due to the speed incompatibility between the wheel and rail,therefore,the wheel-rail impact force is generated.Whether the wheel-rail impact force is considered will cause the difference in phase and amplitude in the subsequent dynamic calculation results,and to describe the whole process of the vehicle wheel-jumping for complete calculation,it is concluded that the wheel-rail impact after the wheel-jumping should be considered.（4）The wheel-rail vibration responses of various wave depths,amplitudes,wavelengths,and different vehicle speed combinations in a single harmonic irregularity are calculated and analyzed,and explored the critical speed of wheel-jumping under each condition.The characteristics and influence laws of each stage in the whole process of wheel-jumping are analyzed.（5）Aiming at the wave depth a₁,wave depth a₂ and wavelengthλ₂ of the compound irregularity in the weld zone that is easy to appear in the high-speed ballasted track,the vibration response of the train-track system and the influence rule of vehicle wheel-jumping are studied.The model of ballasted track considering the failure of the rail fastener cushion and the support failure under the sleeper are established.The condition of single or continuous multiple rail fastener cushion failures,single or continuous multiple support failure under sleepers are set up to analyze the influence law of train-track vertical vibration response,and the critical number of fastener cushion failure and support failure under sleepers of these two kinds of high-speed ballasted track diseases are discussed.There are 52 figures,17 tables and 117 references in this thesis.