Research On Fatigue Strength For Levitation Chassis Of Long Stator Middle-low Speed Maglev Vehicle

Magnetic levitation vehicles is the direction of green traffic for human beings in the future,with the characteristics of Energy saving,Safe and comfortable.The middle-low speed maglev vehicles with the advantage of low noise, low power, good line adaptability and low cost, has become a new competitive public transport inside the city.As an important part of magnetic train.The levitation chassis is not only playing a role of load-bearing and structural coupling,but also the installed base of return roller,air spring and mang other parts.The levitation chassis works under vertical and lateral loading in a complex way. Its structural reliability can affect the safety of the train operation directly,so we need to analyze its fatigue strength and fatigue life.Based on the long stator middle and low speed maglev vehicle of Southwest Jiaotong University, the dissertation carried out the research on finite element statics, fatigue strength and fatigue life analysis of levitation chassis system statics, the detailed research works and main results are as follows.(1) The vertical dynamics model of levitation chassis was established by using ANSYS Workbench and SolidWorks.Four typical working conditions are prepared:the static levitation,driving under normal conditions,emergency braking and stop.lt is analyzed that the load the levitation chassis can bear in the four typical working conditions.Statics analyses are also done in the conditions.The stiffness and static strength of vertical dynamics model are checked,it results they both satisfy the requirements of operation.(2) Based on the result of statics analysis of the levitation chassis, taking a certain amount of key points,using the average equivalent stress and stress amplitude of the key points,adopting correctional fatigue limit diagram,we do the fatigue strength analysis of bracket,outrigger,the up stringer and the down stringer.lt results that the fatigue strength of the four substructure all meets the requirement.(3) Utilizing the analysis of fatigue module of finite element,combining Statics analysis results of the levitation chassis,selecting the modified aluminium alloy S-N curve,we analyze the fatigue life of the levitation chassis in the condition of the static levitation,driving under normal conditions and emergency braking by SN-Goodman mean stress correction theory.And it results that the Fatigue dangerous parts are all located in the joint of the crosswise arc plate and the longitudinal of the left and right outriggers and it is necessary to optimize structure or redesign it.Driving under normal condition is a dangerous working condition,the minimum fatigue life is n2=3.53years. In conclusion, the theoretical analysis and simulation studies on the fatigue strength and fatigue life of the long stator middle-low speed maglev levitation chassis are obtained. The result has reference values for structural improvements of levitation chassis and engineering application in the future, besides it is of great significance to improve riding quality and reliability of maglev vehicle.