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

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.

Key words:wheel-rail rolling contact;unsupported sleeper;rail surface irregularity;ballast track;explicit finite element method