Simulation And Experimental Study On Wheel Steel Friction And Wear Of Heavy Duty Train Under Different Slip Rates

The wheel,an important part of the train walking section,is the only component that contacts the car body and the rail.The creepiness of the train is inevitable and the creepiness of the wheel is one of the main causes of the discontinuous or uneven wear of the rolling contact of the wheel and rail.When the wheel wears seriously,it will cause the wheel tread to be uneven,which will affect the smoothness and comfort of the train.The heavy-duty train will have more serious damage to the wheel and even cause the wheel to break and cause the major safety accident.Therefore,the slip rate is of great research value as an important variable in the study of heavy-duty train wheels.This paper studied the friction and wear characteristics of heavy-duty train wheels through experiments and simulations.The friction and wear tests of CL70 wheel steel under different slip ratios were carried out by GPM-40friction machine.Using dynamics analysis software Ls-dyna simulate the wheel-rail contact area dynamics at different scales,and analysis the contact surface stress.The specific work and conclusions were as follows:Designing wheel-rail friction and wear tests under different slip rates to study the effect of slip rate on surface evolution and performance of the wheel.The results showed that the wheel contact surfacehad displayed plastic deformation and little crushing occurbut no excessive damage,the slip rate had little effect on the wheel wear and friction coefficient.In terms of hardness,the slip rate accelerated the hardening speed of the wheel steel.By analyzing the internal organization photograph of the wheel steel,it was found that the increase of the slip rate leaded to an increase in the thickness of the plastic deformation layer of the surface layer of the wheel.Regarding the overall analysis to the local refinement analysis as the simulation research methodto explore the stress distribution law of the deformation layer during the wheel-rail contact process.Establishingthe actual running wheel-rail contact simulation model to explore the range of stress and strain of the wheel-rail contact part and the position of the maximum stress.Establishingthe friction and wear test simulation model to explore the surface stress characteristics and distribution law of the wheel.Establishing the local contact of the wheel-rail sample to explore the effect of slip rate on the shear stress on surface of wheel.The results of comprehensive tests and simulations showed that the maximum stress of the wheel had appeared on the outermost surface of the contact surface.The microstructure wasthe most obvious in this area and the microhardness was at the peak.The maximum shear stress appeared on the subsurface of the contact surface.Microscopic hardness had a transient platform phenomenon.From the wheel contact surface to the core,the stress tended to be large to small,the internal organization of the wheel was also shredded into a matrix structure.The increase of the slip rate leaded to the upward shift of the shear force spot,the upward shift of shear force spot was also inextricably correlated with the increase of the plastic deformation layer thickness and hardness retention phenomenon in the experiment.