基于POLACH方法的轮轨蠕滑曲线研究

Study on Wheel/rail Creep Curve Based on POLACH’s Method

蠕滑曲线对于描绘轮轨相互作用关系是十分重要的,影响车辆牵引/制动控制、运行平稳性和安全性。选用POLACH基于实测数据提出的接触方法,详细调查影响轮轨蠕滑曲线变化的因素,参变量涵括衰减因子、函数型摩擦因数、轮轨接触几何、轴重和车辆运行速度。研究发现衰减因子可表征轮轨接触界面粗糙度,用以描述蠕滑曲线初始斜率的衰减;函数型摩擦因数则可描述蠕滑曲线在大蠕滑区下降的趋势;轨距角与轨顶处的蠕滑曲线存在不可忽略的差异,这便于解释钢轨小半径曲线侧磨现象;在潮湿工况下,黏着系数随速度的提升而降低,但计算所得黏着系数高于文献报道的实测结果。为此,引入一种考虑运行速度和微滑速度的函数型摩擦因数,取得了与实测数据相吻合的结果。

The creep curve is very important for describing wheel-rail interaction and maintaining good vehicle traction/brake control performance. A detailed investigation is performed on the change of adhesion coefficient as a result of parametric variables such as attenuation factors, slip dependent friction coefficient, wheel/rail contact geometry, wheel load and vehicle running speed based on Polach’s method. The study finds that attenuation factor can represent roughness of wheel/rail interface and describe decay of initial slope of creep curve. Slip dependent friction can represent the decrease of creep curve in large creep zone. The creep curve at rail gauge corner is obviously different from that at rail top, easily explaining the phenomenon of rail side wear at small radius curves. Under wet condition, adhesion coefficient decrease with the increacement of speed. But the calculating adhesion is higher than that measured in field test according to literature. A slip and velocity dependent friction is introduced to obtain reasonable results.