Parametric analysis of wheel wear in high-speed vehicles

In order to reduce the wheel profile wear of highspeed trains and extend the service life of wheels, a dynamic model for a high-speed vehicle was set up, in which the wheelset was regarded as flexible body, and the actual measured track irregularities and line conditions were considered. The wear depth of the wheel profile was calculated by the well-known Archard wear law. Through this model, the influence of the wheel profile, primary suspension stiffness, track gage, and rail cant on the wear of wheel profile were studied through multiple iterafive calculations. Numerical simulation results show that the type XP55 wheel profile has the smallest cumulative wear depth, and the type LM wheel profile has the largest wear depth. To reduce the wear of the wheel profile, the equivalent conicity of the wheel should not be too large or too small. On the other hand, a small primary vertical stiffness, a track gage around 1,435-1,438 mm, and a rail cant around 1：35-1：40 are beneficial for dynamic performance improvement and wheel wear alleviation.

Finite element analysis and experimental validation of polymer-metal contacts in block-on-ring configuration

The wear profile analysis,obtained by different tribometers,is essential to characterise the wear mechanisms.However,most of the available methods did not take the stress distribution over the wear profile in consideration,which causes inaccurate analysis.In this study,the wear profile of polymer–metal contact,obtained by block-on-ring configuration under dry sliding conditions,was analysed using finite element modelling(FEM)and experimental investigation.Archard’s wear equation was integrated into a developed FORTRAN-UMESHMOTION code linked with Abaqus software.A varying wear coefficient(k)values covering both running-in and steady state regions,and a range of applied loads involving both mild and severe wear regions were measured and implemented in the FEM.The FEM was in good agreement with the experiments.The model reproduced the stress distribution profiles under variable testing conditions,while their values were affected by the sliding direction and maximum wear depth(hmax).The largest area of the wear profile,exposed to the average contact stresses,is defined as the normal zone.Whereas the critical zones were characterized by high stress concentrations reaching up to 10 times of that at the normal zone.The wear profile was mapped to identify the critical zone where the stress concentration is the key point in this definition.The surface features were examined in different regions using scanning electron microscope(SEM).Ultimately,SEM analysis showed severer damage features in the critical zone than that in the normal zone as proven by FEM.However,the literature data presented and considered the wear features the same at any point of the wear profile.In this study,the normal zone was determined at a stress value of about 0.5 MPa,whereas the critical zone was at about 5.5 MPa.The wear behaviour of these two zones showed totally different features from one another.