| As a key component for vehicle operation,the wheel bears not only the forces between the wheels and rails,but also the thermal stress generated during starting and braking.Under the dual influence of mechanical and thermal stresses,whether the wheel has sufficient strength is one of the important factors for the safe operation of rail vehicles.This article is based on the Shanxi Provincial Science and Technology Major Project "Research on Key Technologies of Large Diameter and Complex Structure Locomotive Wheels Based on High Reliability Service Conditions",with the aim of improving the strength of metro wheels,to study the temperature field,thermal-mechanical coupling characteristics,and structural optimization of subway wheels.The main research content of this article includes:(1)According to the International Union of Railways standard,0.26 mm interference was selected to establish the metro wheel model,and the influence of axle interference fit on wheel stress was studied.Based on the calculations of the static and fatigue strength and the tightness,the safety reliability of axle interference fit is evaluated.The results are shown that the hub hole contact pressure is distributed in the shape of letter "W" along the axial direction;and the stress of the spoke plate near the wheel hub has significantly increased.(2)Based on the finite element model of the axle-wheel interference fit,considering the change of physical and mechanical properties of materials with temperature,the direct coupling method was used to study the change law and relationship of temperature and coupling stress of metro wheels under tread braking condition.The temperature change rate of the radial direction of the wheel is inversely proportional to the distance of the tread.The coupling stress near the tread on the wheel is affected by temperature.The position near the hub is greatly affected by the interference fit.(3)By studying the influence of mechanical stress and thermal-mechanical coupling stress on the structural strength of the wheel under different wear,the variation law of mechanical stress and coupling stress of the wheel under different wear was obtained,and the safety reliability of the wheel set with limited wear was evaluated.The results show that the maximum stress difference between the new wheel and the wear wheel is 69.3 MPa.When the wheel diameter changes from 820 mm to 810 mm,the coupling stress of the wheel spoke will increase by 24.7 MPa.The coupling stress is relatively stable in the diameter range of 820 mm-840 mm,floating only 9.1 MPa.(4)Taking the S-shaped spoke plate of the wheel as the optimization area,the maximum equivalent stress was minimized as the optimization objective,and the volume of the spoke plate of the vehicle as the constraint condition.The shape optimization of the metro wheel was carried out.After optimization,the angle between the connecting part of the spoke and the wheel hub has been reduced by 1°,and the angle between the connecting part of the spoke and the wheel rim has been reduced by 2° The thickness of the connecting arc with the hub was increased by 3 mm.After the optimization,the maximum equivalent stress of the wheel in the linear condition is reduced by 9.8%.The stress amplitude and mean value of the optimized spoke plate were smaller than those of the original spoke plate,and the fatigue performance of the wheel was better.The wheel performance is improved,which proves the effectiveness of wheel shape optimization.This paper provides a reference for the structural design and optimization of metro wheels. |
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