轮轨间的液态介质和表面微观粗糙度对接触表面疲劳损伤的影响

INFLUENCE OF LIQUID AND MICRO-ROUGHNESS BETWEEN WHEEL AND RAIL ON THE FATIGUE DAMAGE OF CONTACT SURFACE

研究了具有表面微观粗糙度和有液态介质存在于接触表面的轮轨弹塑性接触力学问题,获得了轮轨表面接触应力分布等结果。结果表明,对于有表面微观粗糙度的轮轨,在接触区会出现很大的峰值接触应力,并造成轮轨表面出现塑性。在当载荷卸掉后,钢轨表面还存在严重的残余应力。在列车的多次运行过程后,这样的塑性变形会积累,以至疲劳破坏。给出了接触表面有液态介质和无液态介质的接触应力和残余应力结果。同时还分析了在有液态介质和无液态介质情况下,不同位置的表面微裂纹的裂纹尖端应力,结果表明在有液态介质存在下微观裂纹更易扩展,易导致轮轨表面剥离和断裂。

The elastic-plastic contact problem between rail and wheel is analyzed when the micro-roughness on contact surface and the liquid existing on rail surface are considered. The stresses on contact surface are obtained. A series of peak values of stresses exist on contact surface, which made the material on the surface of rail and wheel go into plasticity. There exist severe residual stresses on the surface of rail when the contact load is unloaded. After the wheel running many times on the rail, the plastic deformation on the rail would accumulate and the surface of rail would fatigue. The contact stresses and residual stresses on contact surface are given for the case of no liquid existing on contact surface and the case of liquid existing on contact surface. The stresses at crack tip for different surfa-cial micro-crack are analyzed for the case of no liquid existing on contact surface and the case of liquid existing on contact surface. The crack is easier to grow and will make the surface of wheel and rail to peel off in the case of liquid existing on contact surface.