车轮踏面不圆顺对高速列车轮轨界面黏着与车轮表面损伤的影响

在JD-DRCF/M型滚动接触疲劳/磨损试验台上开展了有/无偏心车轮配副的轮轨滚滑接触摩擦学试验，对比分析了一阶不圆顺车轮和正常圆顺车轮对轮轨界面黏着、车轮表面损伤与滚动接触疲劳特性的影响。结果表明：车轮不圆顺会显著减小轮轨间黏着系数，湿态下不圆顺车轮的轮轨黏着系数不足0.2,影响列车安全运行和牵引效果；车轮不圆顺明显加剧了钢轨磨耗，同时导致车轮沿周向的表面损伤表现出显著差异。具体来说，凸起侧附近疲劳剥落和撕裂断口特征最为明显；迎向凸起侧较背向凸起侧表面剥落更严重、疲劳裂纹扩展角更大；迎向凸起侧表面点蚀现象相对明显，背向凸起侧车轮表面黏着层堆积严重；此外，随着车轮滚动半径r_θ由最小值到最大值再到最小值循环变化，不圆顺车轮沿周向的表面粗糙度、表面硬度和塑性变形层厚度大致均呈先逐渐增加、经过凸起侧附近后又逐渐下降的趋势。

Effects of Wheel Tread Out-of-roundness on Wheel-rail Interface Adhesionsand Wheel Surface Damages of High-speed Trains#br#

The tribological tests of wheel/rail roll-slip contacts with or without eccentric wheels were carried out on the dual-mode rolling contact fatigue/wear testbed (JD-DRCF/M type). The effects of first-order out-of-round wheels and normal circular wheels on wheel/rail interface adhesions, wheel surface damages and rolling contact fatigue characteristics were compared and analyzed. The results show that the non-roundness of the wheel may significantly reduce the wheel-rail adhesion coefficient, and their wheel-rail adhesion coefficient is less than 0.2 under the wet conditions, which may affect the safe operations and traction effectiveness of trains. The non-roundness of the wheel significantly aggravates wear of the rail and causes obvious difference in wheel surface damages along the circumferential direction. Specifically, the characteristics of fatigue delamination and tearing fracture are most obvious on the convex sides of the wheels. Generally, the surface delamination and pitting are more serious and the fatigue crack propagation angles are larger on the sides facing the convex than that on the sides away from the convex, but the more adhesive layers are accumulated on the sides away from the convex. In addition, the surface roughness, hardness and thickness of plastic deformation layers on the wheels gradually increase at first from the wheel rolling radius rθ changes from the minimum value to the maximum value and then to the minimum value along the circumferential direction, and then gradually decrease after going around the convex.