Study On Contact Stress At The Wheel Seat Of Power Axle Of The CRH Type EMU

The axle is one of the most important parts of the high-speed EMU,which forms the wheelset with the wheel through the interference fit and bears the full weight of the train.The axle of EMU will be subjected to the combined action of the overall weight of the train,wheel rail force and vibration load caused by line irregularities.With the improvement of the speed level of the EMU,the vertical load on the axle,the lateral load on the wheel,the starting torque and the centrifugal force generated by the rotation of the axle will all affect the safety of the axle connection.There will be a decrease in the amount of interference.Once the axle and wheel are separated when the EMU in high speed operation,it will cause the train derailment,turning over and other major catastrophic accidents.The interference volume has great influence on the connection performance.The interference volume is small,and the centrifugal force produced by high speed rotation will release the wheels and the axle.The amount of interference is large,and the material damage is easy to occur during the pressing process,and the contact stress of the axle after assembly may exceed the required range.The theoretical value of the interference amount is the contact stress between the surfaces.Contact stress is the key parameter that affects the interference fit between the wheel and the axle,and it is also the main factor to ensure the successful transfer of motion and load.In this paper,the main factors that affect the safety of the interference fit and their influence rules are studied.The most of factors that may affect the safety of the interference fit are analyzed and concluded.After analysis,the dynamic change of the contact stress between the wheel and axle mainly affected by four influences which are the inertia load,impact load,the heat load generated by the wheel and the brake disc during emergency braking and high speed rotating centrifugal force.First of all,building the finite element model of the wheel and axle;then,the dynamic change of the contact stress between the wheel and axle mainly affected by four influences which are the inertia load,impact load,thermal load of emergency braking.Analyzing the increase or decrease of these factors on contact stress and the micro slip;finally,selecting four typical conditions,analyzing the contact stress variation under different working conditions,combined with the Goodman-Smith diagram to assess the fatigue strength of the axle wheel seat area.