Reliability Analysis Of Service Structure Of Railway Vehicles

Rail transit is recognized as a harmony and green vehicle with low energy consumption and less pollution.Its advantages are well known,but the public is most concerned about its safety and reliability.Vehicles are often faced with problems such as starting and braking,unavoidable overload and poor routine maintenance during service.After long-term operation,the safety and reliability of key structures of vehicles will decline.In order to ensure the safety and reliability of operation,it is very important to study the reliability of service structures of rail vehicles.Bogie is the key component to ensure the safety of rail vehicles.As the framework of the bogie,the bogie is at the core of the bogie structure,and is also the basis for installing other parts.However,due to the complexity of service environment,line condition and welding joint form,it becomes the main area of structural failure.In this paper,the bogie frame of CRH3 high-speed EMU is taken as the research object,and the main research work is as follows:Firstly,the finite element model of the frame is established by using Hypermesh software,and static strength analysis of the frame is carried out by introducing ANSYS software.The maximum Von.Mises stress value and its occurrence position of the frame under 15 working conditions are obtained.The stress value obtained by simulation is compared with the allowable stress of the material in this part,and the static strength check of the bogie frame is completed.Based on the static strength calculation results,the Goodman fatigue limit method is used to check the fatigue strength of the parts with larger stress.The fatigue loading of bogie frame is carried out according to UIC standard,and the fatigue strength of bogie frame is evaluated by IIW standard.The results show that the frame meets the requirements of static strength and fatigue strength.Secondly,taking the secondary evaluation criterion of BS7910 standard as reference,the method of fracture safety assessment of bogie frame is studied.Based on the results of static strength and fatigue simulation analysis of the frame,it is assumed that there are initial defects at a weld dangerous point of the frame,and the safety of the weld dangerous point of the frame is evaluated.According to the different weld positions and different crack length-width ratios a/c of the frame structure,the crack propagation law of the weld defects is studied based on FAD failure assessment chart technology,and the main factors affecting the safety of the frame structure are cracks.Length-width ratio a/c,stress amplitude,plate thickness and material properties.Thirdly,based on the theory of crack growth in fracture mechanics and the theory of linear cumulative damage,the residual life of the frame structure with different initial defects is predicted by using the first-order Paris curve and the second-order Paris curve.It is concluded that when the crack size of the frame structure approaches 10 mm,the crack growth rate will increase sharply.At this time,the close monitoring and control of the working state of the bogie should be strengthened.Time maintenance.Finally,based on fracture mechanics crack growth theory and reliability theory,the fatigue reliability of the frame is analyzed,the crack length model is established,the random variables and their distribution are determined,and the reliability of the frame under different cycles is calculated by programming with Python software.Studying the safety and reliability of service structure is not only an important reference for evaluating the running safety of railway vehicles,but also of great engineering value for the development of railway vehicles in China.