Longitudinal train dynamics during indexer train unloading operations

Train simulation has been used to obtain REPOS for coupler forces for empty, loaded and tippler operations. A head end train with 240 wagons, 36 tal was simulated on a typical heavy haul route. The simulation software was modified to include indexer operation and control to a target trapezoidal velocity profile. The indexer to train connection was modelled as a stiff linear spring, a damper and a gap element. The REPOS of coupler force data at 11 in-train positions (intervals of 10% of train length) were calculated and averaged. The resulting single REPOS spectra were then converted to stress data and damage of each part of the operation assessed.Considering the different parts of the operation separately it was found that fatigue life using loaded train spectra resulted in ~ 1/3rd or less of the fatigue life calculated for an empty train spectra. The fatigue life for tippler unloading, however, was found to be an order of magnitude worse, resulting in 1/10th of the life found for the loaded train spectra. Significantly different results were also found for shorter wagon rakes. The comparison of single rake unloading (240 wagons) verses two half rakes (120 wagons) showed a 4 fold reduction in damage and hence the same increase in fatigue life.