Mechanism Of Rolling Contact Fatigue Initiation Ang Propagation Of1070Steel And Numerical Simulation

Rolling contact fatigue (RCF) is a severe issue for many engineering applications, such as gears, roller bearings and wheel-rail contact. In line rolling contact, when the contact loads exceed the shake-down limit, contact surface displacements will increase with rolling passes, concurrent with residual stresses and strains. The repeated plastic deformations of the material and the rolling contact stresses govern the initiation of rolling contact fatigue.Heavy haul and high speed are trends in railroad industry, and it requires special attention for fatigue of rail-like structures which are subjected to moving contact loads. Rolling contact fatigue failure of rail steel is an important restriction for railway transportation. The study of rolling contact fatigue crack initiation and propagation has great engineering significance.Rolling contact fatigue initiation life, initiation location and crack growth direction of1070steel, under different partial slip conditions, were predicted by the FE method with an advanced cyclic plasticity model and a general multiaxial fatigue criterion. The normal contact pressure and the tangential force follow Hertzian distribution and Carter distribution respectively. Rolling contact processes were carried out by translating the normal pressure and the tangential traction across the contact surface step by step.From the results of the simulations it can be found, with the decreasing of the partial slip coefficient ξ, the initiation life decreases dramatically and initiation tends to occur on contact surface. With the increasing of the maximum contact pressure and Q/P (where Q is the total tangential force, P is the total normal load), the initiation life decreases either, and initiation tends to occur in subsurface. Besides, the angle9(see in Fig.2-6) decreases with increasing of the partial slip coefficient. The high-low loading and the over-loading improve the initiation life. Form the results of propagation it can be found, the cumulative damage of crack tip has two peak values along two directions.