车轮踏面硌伤处的瞬态滚动接触应力分析

摘要

通过建立三维轮轨瞬态滚动接触有限元模型，研究带有踏面硌伤的车轮在指定牵引或制动力条件下的瞬态滚动接触行为，分析不同速度、硌伤几何和材料塑性变形对踏面硌伤处滚动接触行为的影响。结果表明：在60～300 km／h速度范围内，车轮硌伤所激起的接触力随速度的增加而降低；初期硌伤可能存在的边缘“堆起”能大大增加接触应力的水平，或可导致滚动接触疲劳的萌生；对于具有尖锐边缘的硌伤，弹塑性等效应力水平仍可明显大于车轮材料的强度极限，即可发生持续的塑性变形，易于萌生疲劳；相对而言，对于具有钝边缘的硌伤，相应的接触应力水平要低得多，车轮偏于安全。%A 3-D transient wheel/rail rolling contact model was set up by the explicit finite element method.The transi-ent rolling contact between the wheel and the rail was studied in the presence of wheel indentations and the traction or bra-king forces,and the influences of the rolling speed,indentation geometry and material plasticity on transient rolling contact of wheel indentations were analyzed.The results show that,in the speed range of 60~300 km/h,the dynamic force excited by the indentation is decreased with increasing the rolling speed.The pile-up of an indentation is found to greatly increase the stress level,which may initiate the rolling contact fatigue at a late stage.For those indentations with sharp pile-ups,the maximum Von Mises equivalent stress of elastic-plastic materials can still be much larger than the maximum tensile strength of wheel steel,and the continuous plastic deformation may occur to cause the rolling contact fatigue.In contrast, the stress level of an indentation with relatively blunt edges is much lower,and the wheel is probably safe.