Research On Multi-objective Optimization Of Wheel Profile Of CRH3 Platform High Speed EMU

The wheel-rail relationship is one of the key technologies that affect the safety,stability and passenger comfort of high-speed trains.In 2015,the China Railway Corporation established a high-speed wheel-rail deepening study for five years,rolling funding for major projects,and organizing systematic research on high-speed wheel-rail relations.The research on the optimization of wheel-rail profile matching on high-speed railways is one of the main topics.Relying on this subject,this article takes the low conicity swaying problem of CRH3 EMU as the background,explores the causes of low frequency swaying,and carries out multi-objective optimization design of wheel profiles.The specific research work is as follows:?1?A wheel-rail contact geometry model for calculating wheel-rail contact point distribution,equivalent conicity,and normal contact stress was established;based on the dynamic parameters of CRH3 EMU,a multi-rigid body vehicle power with 50 degrees of freedom was established.The model's nonlinear critical velocity is greater than400km/h.?2?Through the tracking test of the wheel profile,a statistical analysis is performed to obtain the evolution law of the wear of the wheel profile and the influence of the wear on the wheel-rail contact and vehicle dynamic performance.The results show that the average wear depth development rate during the repair period is 0.64mm,the equivalent conicity increased from 0.103 to 200,000 kilometers 0.172,the maximum normal contact stress is increasing,and the critical speed of the new wheels is 686 km/h.The critical speed at 200,000 kilometers is 563 km/h,a decrease of 17.9%.The profile wear has a significant impact on vehicle stability and wheel/rail wear performance,and has a small impact on the performance indicators of curve passing.?3?Combined with the measured over-polishing profile of the rails in the swaying car section,the reason for the swaying of the CRH3 car was explored.The problem of swaying usually occurs on the CRH3 type EMU equipped with T70 anti-snake shock absorber shortly after the wheel is repaired.The rail profile of the swaying section has a negative deviation,and the corresponding wheel-rail matching equivalent taper is low,less than 0.08.When swaying occurs,there is a low-frequency shaking of 1?2 Hz,and the lateral stability index exceeds 2.5.The vibration characteristics of the vehicle body are the coupled vibration of rolling and shaking.?4?The arc profile and straight line are used to describe the wheel profile design section,and the correlation between the six arc parameters(R₅,R₆,x _R6,R₇,x _R7,R₈)and the wheel-rail contact and vehicle dynamics is analyzed.The results show that R₅ and R₈have a small impact on wheel-rail contact and vehicle dynamic performance,R₆and x _R6have a significant effect on the curve passing performance indicators,R₇and x _R7 have a large impact on wheel-rail contact and linear running performance,R₆,x _R6,R₇,x _R7should be taken as the key optimization design parameters when the profile is optimized.?5?Based on the multi-objective optimization theory,a mathematical model for multi-objective optimization of wheel profiles was established.The experimental design of Isight and the construction of the RBF agent model were performed,and the NSGA-II algorithm was used to solve the problem.The optimized profile Opt was obtained.Opt and LM_B were compared and verified for wheel-rail contact and vehicle dynamics.At the same time,a wear prediction model was established in UM,and200,000 kilometers of wear prediction and comparison verification were performed for Opt and LM_B.The effect of wheel profile was initially verified by means of simulation.Figure 108,table 19,reference 95.