Research On Railway Vehicle Crashworthiness Based On Multi Body Systems Dynamics

Research on the passive safety for railway vehicle, providing passive safety protection for the occupants was the comprehensive development trend of railway vehicle in the world today. Train was composed of multiple vehicles, to study its crashworthiness, should not only consider the single car impacting damage problem, but also consider the collision between vehicles. Each practical operation of railway vehicle systems would need to provide an acceptable crashworthiness level in their using of environment; this was determined by the energy absorption capacity of railway vehicle that meet the passive safety requirements. In order to achieve the energy absorption capacity, the main components of the energy-absorbing zone in the vehicle ends need to be detailed designed and optimization.The energy-absorbing component was the most important part of energy absorption system of railway vehicle; it directly determined the energy absorption capacity of railway vehicle. This paper took energy-absorbing component as the object of studying, research on the effects of energy-absorbing component performances on one-dimensional crashworthiness of railway vehicle was made using a collision longitudinal dynamics program which was made of MATLAB language, research on the three-dimensional dynamics responses, and the relation between safety collision velocity of railway vehicle and parameters of energy-absorbing component, car mass was made using a three-dimensional collision dynamics coupling model, the main works of this paper were as follows:(1) The domestic and foreign latest research progress of rail vehicles crashworthiness were comprehensively reviewed, and for the first time, we summarized the type and features of rail vehicles collisions, the main research methods of rail vehicles collisions. Last, we focused on detailed analysis and summarizing the principle, research purpose and design methods of rail vehicles crashworthiness.(2) This paper introduced the energy dissipation concept in metal cutting into the field of passive safety protection of rail vehicles. According to two new special energy-absorbing components (cutting energy-absorbing component, cutting and compression combination energy-absorbing component), the numerical simulations of the energy-absorbing process were made using nonlinear large deformation finite element method. The predictive models of interface force stable value and energy absorption of two new energy-absorbing components were developed by using multi-linear regression analysis. The results show that the regression equations and coefficients were of significances, there was a linear relationship between predictive models and cutting parameters (tool rake angle, chip central angle, cutting depth and cutting speed). Test simulation show that the prediction models were effective.(3) Based on dynamics and collision mechanics theory, one-dimensional collision dynamics equations of railway vehicle were made of Matlab language using explicit integration method. The safety evaluation indices and criteria of railway vehicle crashworthiness were summarized. The basic characteristics of cutting energy-absorbing components in vehicle ends were created using the simplified force-deformation curves, based on these curves, the force displacement functions of car ends cutting energy-absorbing components were defined. Taking the variable of these force displacement functions as analysis variables, the effects of energy-absorbing component performances on one-dimensional crashworthiness of railway vehicle were made, the main control parameter of safety evaluation indices was found, the influence law of energy-absorbing component performances on safety evaluation indices were made.(4) A three-dimensional dynamics coupling model of a railway vehicle was established which including the vehicle subsystem, the wheel/rail subsystem, the coupler buffer, anti-climber energy-absorbing component subsystem. The model included a detailed coupler model, wheel-rail contact relationship, interaction between anti-climbers, force-displacement characteristics of energy absorption parts in the vehicles ends and the nonlinear dynamic stiffness characteristics of stop devices, suspension systems were presented. The system motion equations were solved by means of an explicit integration method in the time domain using Matlab language. The effects of energy-absorbing component parameters, car mass on crashworthiness of railway vehicle were made. The predictive model of the relation between safety collision velocity of railway vehicle and parameters of energy-absorbing component, car mass were developed by using multi-linear regression analysis. The results show that, in case of straight line railway vehicle central collision in medium and low speed would not produce the derailment risk. The analysis of variance indicated that the regression equation and coefficients of predictive model were of significances. Test simulations show that the prediction model was effective.