Dynamics Simulation And Suspension Parameter Optimization Based Rigid-flexible Coupling Bogies

In recent years,lightweight design has been widely used in rail vehicles in order to make rail vehicles run faster.However,the lightweight design changes the overall stiffness while reducing the vehicle mass,so that the external load excitation has a more significant effect on the dynamics performance during the vehicle operation.Therefore,to ensure the smoothness of vehicle operation,the dynamics performance of high-speed train system is studied.In this paper,a rigid-flexible coupling model is introduced for dynamics simulation analysis to obtain the vehicle dynamics response and optimize the design of suspension parameters.The specific work is as follows:(1)Rigid-flexible coupling vehicle model establishment and modal analysis.A solid unit model is established for the bogie frame and Wheelset,and the flexible Wheelset and frame are generated through modal calculation and sub-structure analysis and collaborative dynamics simulation analysis;a multi-rigid single vehicle model is established based on the suspension parameters of the built-in axle box bogie of a rolling stock trailer;the flexible bogie and flexible Wheelset are coupling into the multi-rigid vehicle model to obtain the rigid-flexible coupling vehicle model.(2)The dynamics performance of the rigid-flexible coupled vehicle model is analyzed.The nonlinear critical speeds of 648 km/h and 660 km/h are calculated for the rigid-flexible coupling model and the multi-stiff body model,respectively.in addition,the maximum value and root mean square of the dynamic performance response of the rigid-flexible coupling model are obtained under different speeds and different line conditions,and the derailment coefficients and sperling values of the rigid-flexible coupling model and the multi-stiff body model are compared and analyzed.The simulation results show that the maximum value and root mean square of the dynamic performance response of the rigid-flexible coupling model increase with the increase of speed,which is in accordance with the requirements of GB/T5599-2019 standard;the derailment coefficient and sperling value of the rigid-flexible coupling model are higher than those of the multi-rigid body model,and the growth trends of the dynamic response indexes of the two models are similar.(3)Built-in axlebox bogie suspension parameters optimization.In order to improve the vehicle dynamics performance,the suspension parameters are optimized for the rigid-flexible coupling model and the multi-rigid body model,respectively.The optimal Latin superlift method is used for experimental design to analyze the influence of each suspension parameter on the dynamic performance;the radial basis function approximation model is fitted to the two models with the suspension parameters as design variables and the dynamic performance indexes as responses;the suspension parameters are optimized based on the approximation model using NSGA-II algorithm;and the applicability of the optimized design variables is verified for the whole operation process and different speed conditions.The optimization results show that the kinetic response indexes of derailment coefficient,vertical vibration acceleration,transverse vibration acceleration,wheel-rail transverse force and wheel-axle transverse force of the rigid-flexible coupling model are improved by 3.14%,20.11%,6.13%,0.82% and 2.19%,respectively,and the kinetic response indexes of the multi-rigid body model are improved by 2.26%,19.83%,9.10%,0.64% and It is verified that the optimized suspension parameters are still applicable throughout the operation process and under different speed conditions;by comparing the difference changes of the two models before and after optimization,it is obtained that the rigid-flexible coupling model is more optimized and has more room for optimization.In this thesis,a simulation and analysis model of vehicle dynamics with rigid-flexible coupling is established by using the substructure analysis method,and the dynamic performance of the vehicle is systematically analyzed and the suspension parameters are optimized.It provides a reference for vehicle dynamics test and practical application,and has some reference value in the design of bogie suspension parameters.