PSI - Issue 4

Uwe Oßberger et al. / Procedia Structural Integrity 4 (2017) 106–114 Author name / Structural Integrity Procedia 00 (2017) 000 – 000

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Fig. 6. From 2D measurements to 3D geometry monitoring. (a) sketch of the crossing with red lines indicating the positions of the 2D measurements; (b) 3D reconstruction of the crossing geometry after 31 months (58 MGT load) with a color code indicating the geometry changes with respect to the first measurement in track; (c) enlarged corresponding area of the picture shown in Fig.1 In the next step, the measured geometry is further analyzed with respect to its transition geometry. For this, an ORE-S1002 standard wheel profile, centered to the axis of the track is numerically put in contact with the crossing shape at each measured cross-section (independently for the wing-rail and the crossing nose). The result of rigid contact calculation is a vertical wheel position trajectory, based on the fact that wheels usually have a cone-like shape. The changes of trajectories are shown in Fig. 7:

Fig. 7. Vertical wheel position trajectories of an ORE-S1002 standard wheel profile, centered on the axis of the track, moving through an instrumented fixed crossing.

The evaluation of wheel position trajectories gives information about the quality of the transition process. It can be seen that the wheel follows first the left wing-rail trajectory, changes at the intersection point of wing-rail and crossing-nose trajectory to the crossing-nose trajectory and follows the crossing-nose trajectory. Based on the fact that wheels have a cone-like wheel shape, a vertical wheel movement towards the intersection point is observed. The presented measurement results show typical wheel position trajectories of a fixed crossing without wing-rail elevation (e.g. sometimes added in casted crossings). It is noticeable that only minor changes in transition process can be seen here. Some higher degradation values are visible in the transition region; nevertheless there is no influence on the longitudinal transition point location and the impact angle (angle between wing rail and crossing-nose trajectory). These facts are a result of the high strength tool steel crossing nose material which allows only slight geometry changes due to wear.