Fatigue Life Evaluation Of Wheel Set Axle Box Of HX_N3 Locomotive

With the development of railway transportation in the direction of high-speed and heavy load,the stability of locomotive bogie is particularly important.While ensuring the stable transmission of traction and braking force,the bogie also needs to transmit the load of various components on the vehicles.The axle box of the bogie belongs to a connecting component that takes into account the three functions of bearing motor,sealed axle and lubricated axle.The damage of the mechanical structure of the axle box will affect the lubrication of locomotive axle bush,and even cause the motor to fall off,which eventually leads to accidents.Taking the axle box of HX_N3 diesel locomotive bogie as the research object,this paper establishes the finite element model of axle box by using the finite element analysis software,and analyzes its static strength,mode and fatigue strength,so as to ensure the good mechanical performance of HX_N3 diesel locomotive wheel to axle box.The main research contents are as follows:(1)By analyzing the solid model of the wheel set axle box structure of HX_N3 diesel locomotive,the finite element model of the bogie wheel set axle box of HX_N3 diesel locomotive is established using Hyper Mesh By analyzing the working conditions of the locomotive during operation,two static strength load conditions,transverse and longitudinal,are summarized.Under the transverse load condition,the maximum Von Mises stress value is177MPa,which occurs at the edge of the sixth bolt hole of the traction motor mounting seat of HX_N3 internal combustion engine wheel to axle box,the stress value is less than the allowable stress,and the safety factor is 1.94;The maximum Von Mises stress under the vertical load condition is 10MPa,which occurs at the junction of the lower left traction motor mounting seat of the axle box and the shaft sleeve.The stress value is less than the allowable stress.The results show that the axle box structure meets the requirements of static strength design.(2)According to the requirements of BS 7608-1993 and in combination with the actual operation characteristics of HX_N3 diesel locomotive,the fatigue load conditions of HX_N3diesel locomotive suspension axle box in three directions are obtained,and the first principal stress of suspension axle box under three load conditions is calculated.The results show that there will be fatigue fracture in the axle box structure under the action of transverse load.The axle box structure does not meet the fatigue strength design requirements,and the axle box structure needs to be further optimized.(3)The first six modes of the axle box structure are determined through modal analysis,and the harmonic response of the brake module is analyzed within the first six frequency ranges to obtain the displacement response and stress response of the measuring points under different working conditions.Based on IEC 61373-2010,the random vibration fatigue life of the axle box structure is calculated.The results show that the small life of the axle box is29.8h under the action of the transverse acceleration power spectrum,the minimum life of the axle box is 17838h under the action of the vertical acceleration power spectrum,and the minimum life of the axle box damage is 12.5h under the action of the longitudinal acceleration power spectrum.The results show that the random vibration fatigue life of the axle box of the bogie of HX_N3 diesel locomotive under the action of the acceleration power spectrum in the longitudinal,transverse and vertical directions is greater than the minimum 5h in the transverse direction required by the standard,and there is no defect of random vibration fatigue life.(4)According to the analysis of the causes of fatigue fracture,the objective of structural optimization of wheel pair axle box of HX_N3 internal combustion engine is given.The size of the wheel axle box structure of HX_N3 internal combustion engine is optimized,and the axle box meeting the design requirements is obtained.The topology optimization of the new structure after size optimization is carried out,the shape of the model is optimized according to the results of topology optimization,and the fatigue strength of the new structure is checked.The results show that the quality of the optimized structure is reduced by 21.99%compared with the original structure,and the maximum first principal stress of the new structure is reduced by 56.18%compared with the original structure.The purpose of lightweight is achieved.