Research On Fatigue Reliability Of Frame Based On Line Measurement And Maintenance Data

The subway has become one of the best choices for urban public transportation due to its advantages such as large traffic volume,fast speed,high punctuality,and land saving.With the rapid development of urban rail transit,higher requirements are put forward for the safety of metro vehicle operations.The fatigue strength of the bogie frame is an important factor to ensure the safe operation of the vehicle.At present,most metro vehicles use welded frames to reduce their own weight and achieve lightweight requirements.However,under complex loads,welded joints have become the main areas of structural failure.How to determine the reasonable maintenance cycle of the bogie frame under the premise of ensuring the safety of the bogie frame is also one of the topics that need to be carried out in-depth research.This paper takes the metro vehicle bogie frame as the research object,obtains the stress signal of the key parts of the frame through the actual line test,studies its fatigue reliability,and provides data support for formulating a reasonable maintenance cycle.The following work is mainly completed:(1)The reasonable arrangement scheme of dynamic stress and vibration measuring points for bogie frame of two types of metro vehicles is formulated,and the field test of bogie frame line is carried out.The dynamic stress data and vibration acceleration data of the measuring points of the key parts of the frame are obtained when the metro vehicle is running normally on the line,which provides data support for the fatigue strength evaluation of the bogie frame.(2)The frame stress spectrum is prepared by the rain flow counting method.Combined with the S-N curve and Miner linear fatigue cumulative damage rule,the equivalent stress of the key components of the frame under different operating mileages is calculated.The fatigue strength of bogie frame is evaluated,and the position where the frame stress level is large is determined.The research work is of great significance to the optimization design of bogie frame structure.(3)The data processing and analysis of the acceleration of the frame obtained by the line test are carried out,and the acceleration-time history of the frame is obtained.According to the situation of subway operation stations,the acceleration-time history of bogie frame and the stress-time history of measuring points are segmented.The RMS value of vibration acceleration of bogie frame and the equivalent stress of measuring points between each station are calculated and obtained.The correlation between the acceleration of bogie frame and the equivalent stress of measuring points is analyzed.The functional relationship between the acceleration of bogie frame and the equivalent stress of measuring points in key parts of bogie frame is established,which provides a basis for simplifying the reliability evaluation of bogie frame structure and determining the track state between stations.(4)According to the reliability theory and method,the maintenance data of metro bogie frame on the tested line are analyzed,and the failure probability model of the key parts of the bogie frame is constructed.The failure probability of the key parts of the frame under different mileages is obtained.The research work provides data support for the formulation of a reasonable frame maintenance cycle.