Research On Wheel Wear And Wheel Profile Optimization Of High Speed Train

Wheel/rail match is one of the most essential issues in wheel/rail relationship，which has a direct influence on the interaction of the wheels and the dynamicperformance of the vehicle. With the massive high-speed operation of EMUs，theproblem of wheel/rail wear is becoming increasingly prominent, the wheel/railmatching and contact are therefore changed with the wheel wear. Severe wear willhave a negative impact on the vehicle safety and stability. Under the establishedwheel/rail structure system and operating environment, optimizing the wheel profileand finding the optimal low-wear wheel profile will be the most economical and mosteffective means to less the wear problem.Based on the of wheel rail rolling contact theory, the wear numerical analysismethod of Archard and Specht model combined with vehicle track system dynamicsmodel are adopted in this paper, and wheel wear prediction results are obtained andthe comparative analysis with the measured wear data is carried on. Wheel profiledescription method is established on the basis of Nnon-Uuniform Rrational BSspline curve theory(NURBS),and the multi-objective optimization model oflow-wear wheel profile is set up; improved Particle Swarm Optimization(PSO)algorithm is designed and introduced to solve the optimization model. Thecomparative wear and dynamic characteristics analysis of the CN wheel profile andthe CN-OPTI optimal profile under different conditions are achieved, which makes itfeasible to judge the performance of the optimal wheel profile comprehensively.The main work of this paper is as follows:(1)This paper illustrates the research background and the practical significanceof wheel/rail wear from home and abroad and summarizes its history, developmentand the research findings on numerical prediction model, field measurements andlaboratory research; describes the four fundamental wear prediction calculationmodels of Pearce，Zobory，Jendel and Enblomd; gives a full account of the researchhistory, technique methods and the findings of profile optimization, and provides aparticular description of the two optimization methods of Heller，Choromanski，Shevtsov model and wheel profile design considering the normal gap of the wheel/railand wheel profile design described by arcs. (2)The equivalent conicity is used to characterize wheel/rail contact geometryand has great influence on the running behavior of railway vehicle. This paperpresents the contrast and comparative analysis of the two calculations of quasi-linearfunction of KLINGEL and the linear regression of the rolling radii differencefunctionDr,the results show that,for the LMA/CHN60and CN/CHN60pairs, theequivalent conicity results of two algorithms has good consistency when y is within1to6mm, and equivalent conicity difference is increased increases when y is biggerthan6mm; for the XP55/CHN60pairs, the equivalent conicity results of twoalgorithms has good consistency when y is within3to9mm, and the equivalentconicity difference is increases when y in remaining range;(3)Bbased on the wheel rail normal and tangential contact theory, wheel/railcreep force is obtain by use four models of linear creep theory and the simplifiedtheory of Kalker, non-elliptical rolling contact theory and the semi-Hertz rollingcontact theory. and semi-Hertz rolling contact model is adopted in this paper aftercomparative analysis.(4)Vehicle-track coupling dynamic model of CRH3EMU and its verification bythe comparison analysis of the vibration characteristics under three experimentalconditions are accomplished:①as for anti-hunting damper T60, there is vehiclelateral resonance frequency of0.9-2Hz when wheel profile is LMA, and the vehicleinstability disappears when LMA is replaced with CN.②in the case of replacementanti-hunting damper of T70with T60, the vehicle lateral hunting frequency of1-2.5Hz is not obvious;③as20-30million kilometers operation, the phenomenon ofbogie hunting instability of6-10Hz weakens in the case of replacement anti-huntingdamper of T60with T70.(5) Two wheel wear numerical model of Archard and Specht are established andwheel tread wear simulation is finished basing on rolling contact model. comparedwith measured wheel wear data of ZE300100vehicle on Beijing-Tianjinhigh-speed railway, change trend of wheel tread wear rate and equivalent conicitycalculated with the Archard model fits well better with the measured data than Spechtmodel.(6) Two parameters of inertia weight and acceleration factor of the standard Particle Swarm Optimization(PSO) are improved, test performances of theOptimized PSO(OPSO) use3well-known benchmark functions are achieve andresults show that the OPSO can reduce the calculation time of9.85%~13.25%andquicken global optimization iterations with18.2%~23.03%, which indicate theOPSO has good search ability and convergence characteristics;(7)Based on the Non-Uniform Rational B Spline (NURBS) curve theory,combined with the wheel profile characteristic, the curve length at x=[1,120]mm isuniformly divided into N-1arcs to obtain N data points as well as the correspondingN+2weight factors, continuity, smoothness, monotonicity and convexity-concavity ofprofile are chosen as the constraint conditions, the reconstruction method of cubicNURBS of CN wheel profile is established. On three occasions of N=15,20,25,correlation coefficient between the CN profile and the cubic NURBS reconstruc-tion profile is0.83,0.93,0.95respectively. Comprehensive analysis has indicated thatselection of20data points has shown better results in describing CN wheel profiles.(8)Multi-objective optimization model of low wear wheel profile of CRH3isdesigned, combined with the vehicle-track coupling dynamics model, the optimalprofile CN-OPTI is obtained based on the PSO algorithm.①Analysis of wheel-rail contact has indicated that the contact distribution ofCN-OPTI/CHN60pairs is more uniform than that of CN/CHN60pair, meanwhile, theless point of flange contact with rail side is found, which contributes to reduction offlange wear and rail side wear. CN-OPTI demonstrates good adaptability to thevarious gauge and rail cant.②By comparing the two worn profiles of15million kilometers calculatedwith Archard and Specht wear model, it can be concluded that CN-OPTI worn profilewear rate is slower than CN worn profile, so does the equivalent conicity.③the lateral displacement, the attack angle, the MAX pressure and the wearwork is improves by using the CN-OPTI worn wheel profile when passing bigradius curve, the lateral force of vehicle and bogie has little improvement,derailment coefficient of front bogie has no change, wheel load reduction rate isincreased slightly, but remain in the safety limits.④Based on Archard wear model, the two worn wheels of15million kilometers is obtained. compared with CN profile,the wheel wear rate is smaller,and thecomprehensive performance of CN-OPTI worn wheel is better than CN worn wheelas for three wheel-rail pairs of new wheel/worn rail,worn wheel/new rail and wornwheel/worn rail on. derailment coefficient, wheel load reduction rato and lateral forceof worn CN-OPTI wheel is in the safety range.