| The large passenger capacity,frequent start and stop,complex circuit conditions and high frequency use of metro vehicles put forward high requirements for the fatigue reliability of vehicles’ key structures.Bogie frame is a key component of metro vehicle running system,which is designed and applied according to the whole life cycle.Its fatigue performance is crucial to the safety of vehicle operation.Clarifying service load can greatly ensure the fatigue reliability of frame.On the basis of obtaining the bogie frame’s actual load,this thesis studies the load characteristics,establishes the damage consistent load spectrum in line with the actual operating conditions,and carries out the damage prediction application research of the load spectrum,which provides data and method support for the establishment of the bogie structural strength design specification and reliability test evaluation standard in line with the domestic metro vehicle operation situation.The main research and results are as follows:(1)Aiming at the passenger capacity and the distribution characteristics of fatigue damage in the inbound,outbound,linear and curve conditions,the automatic identification of working conditions and extraction methods are studied with the fatigue damage as the main determinant criterion,which realized the accurate automatic segmentation of working conditions and the corresponding data extraction.Furthermore,based on the load time domain signal under each working condition,the characteristics of each load action are studied through the statistics and variation trend in the load time domain,which lays the foundation for the compilation of the load spectrum.(2)The global coordinate system is established.According to the movement condition,load’s source and load action direction of the frame,the frame load is divided into three groups,namely primary vertical load,load in the horizontal plane and drive system load.(3)The quasi-static and dynamic parts of stress components are studied.Based on the safety and symmetry of the frame,the fatigue control parts of the frame were screened.The stress calculation method is studied under the quasi-static frame,and then the calibration of the whole domain load is completed.After calibration,the calculated stress covers the measured stress with high precision,and both have high matching degree in time domain and frequency domain.(4)The positive and negative characteristics of load correlation under different working conditions are calculated.The direction of load action is determined.The load amplitude of maximum damage level is selected,and its action frequency is determined according to damage consistent criterion.The the working condition test load spectrum was preliminarily compiled,and the damage consistent calibration of the working condition test the load spectrum was carried out.The calibrated load spectrum of each working condition covers the measured damage with high accuracy,which provides a basis for fatigue tests under different working conditions.(5)Based on the maximum amplitude of each load in the load spectrum of each working condition,the working condition load spectrum is merged,and the corresponding action frequency of the load is obtained.Thus,the combined working condition load spectrum of the vehicle running on the whole line is compiled.The combined working condition load spectrum can cover the measured damage with high accuracy.Based on the measured service load and fatigue damage of the frame,the characteristics of load and damage under different working conditions are studied in this thesis.The calculation load spectrum of frame fatigue damage and the load spectrum of fatigue reliability verification test were preliminarily constructed,which provided the method basis for establishing the fatigue test verification standard conforming to the service condition of metro vehicles in China.80 figures,34 tables,and 93 references. |
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