Finite Element Analysis Of High Speed Railway Wheel/Rail Rolling Contact Fatigue Crack Initiation And Propagation

In recent years, railway transport has been developing to high speed and heavy duty continuously, and creates the huge economic benefit and social benefit. However, high speed railway transport puts forward a series of challenges to scientific research, many of the key scientific and technological problems need to solve. The wheel/rail contact fatigue crack damage is the most complex scientific problem in the railway transportation problem.Contact fatigue crack initiation and propagation is closely related to the wheel/rail contact stress, so to solve the wheel/rail contact stress is the key problem which research the crack initiation and propagation status. This paper uses three dimensional modeling software Pro/E to build the model according to the real wheel/rail geometry shape. ANSYS was utilized to analyze the influence of contact fatigue crack initiation in different axle loads, friction coefficients and traction torque, respectively. Then the finite element model with crack was built in the basis of original model.The influence of crack tip stress intensity factor was calculation and analysis in the different axle load, friction coefficient and vehicle speed.The calculation results show that:about the fatigue crack initiation, with the increase of axle load and traction torque, wheel/rail contact shear stress and Mises stress will increase gradually, intensifies the plastic deformation and plastic flow, speeding up the fatigue crack initiation speed; The increase of friction coefficient make the vertical shear stress and longitudinal shear stress have growing tendency. This trend will also speed up the fatigue crack initiation. About the fatigue crack propagation, axle load has a great influence to crack tip stress intensity factor. As the increase of the vehicle speed, stress intensity factor increases gradually, accelerate the fatigue crack growth rate. With the increase of friction coefficient, the crack tip stress intensity factor will decrease gradually. This shows that rail is daubed oil could decrease wear, but oil will make the stress intensity factor increase, speed up the crack propagation.These research results help formulate alleviate fatigue crack damage measures. Contact stress could be reduced through the optimization of the wheel/rail contact type surface. In this paper, before and after optimization of wheel/rail contact Mises stress were compared, the optimized stress value decreased obviously, and achieved the purpose of optimized wheel tread. Preventive grinding technology makes use of the turning point which fatigue crack growth rate to vertical direction started to increase. The rail head surface fatigue crack is controlled before vertical extension.