Research On Wheel Thermal Friction Damage And Thermal Fatigue Life During Tread Braking Process Of Heavy Haul Train

With the increase of train speed and axle load,and the deterioration of the service environment,the wheel tread of the train heats up rapidly in a short time during the braking process.The heat generated by the friction between the wheel tread and the brake shoe is transferred to the inside of the wheel and the brake shoe through the contact surface.Due to the uneven temperature distribution inside the wheel,a certain thermal stress is generated.Under the combined action of the alternating load between the wheel and the rail,the thermal peeling damage and failure problem of the wheel tread becomes more serious.In addition,the temperature of the wheel tread has been at a high level for a long time.The increase in temperature not only changes the properties of the wheel material,reduces the hardness and strength of the material,but also increases the thermal stress.Under the combined action of mechanical load and thermal stress,the wheel Treads are more prone to damage.In order to predict the tread wear depth of the train under different braking conditions,after determining the thermal physical parameters of the wheel material at different temperatures,a finite element model of the wheel counter rotating thermo mechanical coupling was established based on the Abaqus finite element software,and the modeling process In the process of comprehensively considering the impact of braking temperature rise on the mechanical properties,hardness and friction coefficient of the wheel tread,the temperature distribution,hardness distribution and contact stress distribution on the wheel tread during the emergency braking process are obtained through simulation,and the wheel-rail dynamics software UM is used.The shape of wheel-rail contact spots and the relative slip distribution of wheel-rail creep area during emergency braking are obtained.Based on this,combined with Archard wear model,the wear depth after emergency braking is quantitatively predicted.The wheel tread will produce thermal fatigue damage under the combined action of thermal stress and periodic radial and tangential stress in the contact area of the brake shoe and the contact spot of the steel rail.On the basis of obtaining the transient temperature field,stress field and strain field distribution of the tread,according to the multi-axis fatigue model proposed by Jiang and Sehitoglu based on the energy density and the critical plane method,the position of the maximum damage parameter in the axial direction of the tread during the braking process and The relationship between tread temperature,axle load,brake shoe pressure and damage parameters can be used to quantitatively predict the thermal fatigue crack initiation life of the tread.