Research On Fatigue Strength Of Antenna Beam Of Subway Bogies

In recent years,China’s urban rail transit has developed rapidly.By the end of 2019,38 cities have opened subways and the running mileage has reached 5902.64 kilometers.The wide application of subway vehicles has made the structural safety of rail vehicles much concerned.The antenna beam is the mechanical structure responsible for fixing the ATC antenna.It is installed at the end of the bogie.Long-term service in a complex vibration environment is prone to vibration fatigue damage.The antenna beam structure of the bogie of Shenzhen Metro Line 1 has experienced fatigue cracks during use,which seriously endangers the safety of driving.In order to solve this problem,dynamic stress and acceleration line test experiments were carried out on the antenna beam structure,and the fatigue strength evaluation of the structure was carried out based on the measured stress time history.The results showed that the fatigue life of multiple measurement points did not meet the requirements;multiple frequency domains method were used to calculate the fatigue damage of the stress measuring point,and compares the calculation results of the narrow-band method,Dirlik method,and Lalanne method with the fatigue damage results of the time domain method.The results show that the calculation results of the Dirlik method are more accurate;according to the frequency domain and time domain characteristics of the dynamic stress and acceleration data,the modal of the antenna beam is analyzed during vehicle running.The acceleration excitation from the end of the bogie frame stimulates two modes of natural frequencies of 68 Hz and 92Hz;using finite element analysis software performs modal analysis and harmonic response analysis of the antenna beam structure.The modal analysis result shows that the first two modes of the structure are 65.1 Hz and 96.6 Hz,which are consistent with the structural modal frequency reflected by the measured data,and the relative error is less than 5%.Both verifying the structural resonance and the accuracy of the finite element model;using the finite element dynamic strength analysis performed impact strength verification according to the IEC-61373 standard.The results showed that the antenna beam met the impact strength requirements.Using standard load and measured load,combined with Dirlik method to perform random vibration fatigue simulation strength check of antenna beam.The results showed that the antenna beam structure did not meet the vibration fatigue strength requirements,and the fatigue damage was greater than 1.The position appears at the upper and lower bends of the inner installation floor,which is the same as the actual crack occurrence position;the antenna beam is structurally optimized,and the finite element analysis software is used to perform modal analysis and simulation verification on the optimized structure.The results show the first-order mode of the optimized structure is increased by 153.5%,and the fatigue strength and impact strength meet the requirements of use.92 pictures,16 tables,57 references...