| The vehicle body is an important bearing structure of the rail vehicle,which is subjected to complex dynamic alternating loads during the operation of the vehicle.In recent years,the railway carriage is continuously developed in the direction of high speed,comfort and lightweight.However,which also leads the vehicle body to bear more complicated alternating load,this situation increases the probability of fatigue fracture in the vehicle body structure.The safety and reliability of vehicle body directly affect the safety operation of the train,so it is very important to study the fatigue performance of high-speed train body.Firstly,the fatigue research situation at home and abroad and the fatigue related theory are summarized in this paper.Secondly,the CRH3 EMU and the welding structure under inertial load were taken as the research object,based on the finite element method(FEM),the fatigue characteristics of the welding structure under inertial loading were caculated and analyzed by using of the Master S-N Curve Method.On this basis,the anti-fatigue performance of high-speed train body is studied by using of the Infinite Life Design Method,the Master S-N Curve Method and the Nominal Stress Method respectively.The main contents are as follows.(1)Using HyperMesh software,the finite element model of vehicle body was established,and the stiffness,static strength and modals of the vehicle body were analyzed by using of Nastran software.(2)Taking the welding structure with the fillet welding and the butt welding under the effect of inertial load as the research object,the fatigue characteristics of the welding structure were caculated and analyzed by combining the Fe-Safe/Verity module and the Master S-N Curve Method,the sensitivity of the structure nominal stress and the structure equivalent stress respect to the grid size were analyzed,the structural stress distribution characteristics of two types of welding seams were studied,and the effect of load form,weld type and structure size on fatigue life of structure were analyzed.(3)According to the BS EN12663-2010 standard,the fatigue strength of the high-speed train vehicle body in the overstaffed state was analyzed under the fatigue load.According to the fatigue strength,the fatigue life of the vehicle body was predicted by using of the Infinite Life Design Method.(4)Based on the Master S-N Curve Method in the ASME-2007 standard,the fatigue life of important welds was evaluated.Firstly,on the basis of the vehicle body fatigue strength,86 important welds were selected from the chassis floor,the traction beam and pillow beam,end wall,side wall and roof plate.Secondly,the structure stress range and the equivalent stress range in the welds were calculated.Lastly,by selecting the relevant S-N curv,the damage ratio of the welds under three load cases,fatigue life and cumulative damage value were calculated,and the fatigue performance of the car body was evaluated.(5)Based on The Nominal Stress Method in the IIW-2008 standard,the fatigue life of the vehicle body was evaluated.Firstly,the evaluated welds were determined,and then the fatigue level and S-Ncurve of evaluated welds were choosen.Lastly,the damage value,fatigue life and cumulative damage value of the welds were calculated,and the anti-fatigue performance of the vehicle welds was evaluated.(6)The advantages,disadvantages and applicability of the three methods were compared based on the evaluation results of the Infinite Life Design Method,The Master S-NCurve Method and The Nominal Stress Method.The results show that fatigue life of the vehicle body meets the design requirements,and the evaluation result based on the Master S-N Curve Method is more accurate,reasonable and conservative;the welds fatigue damage of car body is the more serious and the fatigue life is less low under the transverse vibration load. |
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