轨枕空吊对钢轨焊接不平顺区轮轨接触的影响

Influence of Unsupported Sleeper on Wheel-rail Contact at Rail Weld Irregularity

摘要:

采用显式有限元法建立考虑有砟道床非线性支撑的三维轮轨瞬态滚动接触模型，于时域内再现轨枕空吊和钢轨焊接接头不平顺共同激扰下的轮轨滚动接触行为，研究了轨枕的空吊间隙和数量对焊接不平顺区轮轨瞬态相互作用的影响。结果表明：轨枕完全空吊会进一步加剧焊接不平顺区的轮轨冲击效应，进而加大了钢轨表层材料的屈服变形，且屈服程度随空吊轨枕数量的增长而增长；焊接接头处2根毗邻轨枕完全空吊条件下，法向轮轨力、瞬态接触应力、接触斑面积和von Mises等效应变等轮轨接触参数较无轨枕空吊时分别增长14.5%、4.2%、8.5%和6.7%，轨面垂向位移的增幅达到72.0%，而接触斑内黏着与滑移区比例的变化则相对较小；当焊接接头处1根轨枕的空吊间隙超过1.0 mm或2根毗邻轨枕的空吊间隙超过1.3 mm时，前述轮轨接触参数会随着轨枕空吊间隙增长而增长迅速，直至出现轨枕完全空吊现象。

Abstract:

A 3D wheel-rail transient rolling contact model accounting for sleeper hanging behavior was developed based on the explicit finite element method. The dynamic wheel-rail interaction affected by both rail surface irregularity and unsupported sleepers is reproduced， and the influence of hanging gap and number of sleepers at rail weld irregularity is analyzed. The results indicate that the presence of unsupported sleepers enlarges wheel-rail impact at rail weld irregularity. Subsequently， the yield deformation of rail materials was exacerbated， and the situation becomes even worse with the growth of unsupported sleeper number. Under the condition of 2 adjacent sleepers being completely unsupported， the parameters in terms of wheel-rail contact force， contact stress， contact patch size and von Mises strain of rail top-layer elements increase by 14.5%， 4.2%， 8.5% and 6.7% compared to nominal condition， the vertical displacement of rail surface nodes rises by 72.0% in the meantime， whereas the distribution of adhesion-slip state is much less affected. Meanwhile. under the incompletely unsupported condition， the preceding contact parameters rise rapidly as the hanging gap is higher than 1.0 mm for 1 sleeper or 1.3 mm for 2 adjacent sleepers， until completely unsupported condition occurs.