RTR 4/2010 9 Frequencies of the ballasted track n in the front wave of the rail we look at this unloaded area of the ballasted track in the following chapter. 5 Calculated results of the unloaded track-system Figs. 8 and 9 are showing the long-wavy eigenfunctions (modes) of the unloaded ballasted track with the week rail pads (RP). The dense sequence of the two eigenvalues – at 81.5 and 81.7 Hz – points out that we have an accumulation area. Rails and of rail but interacting with the brake discs. Between 160 and 210 Hz there are large sleeper displacements in the direct surrounding of the wheel set, where the stiffer rail pads are placed. Comparing these calculated results with the measured ones of Fig. 1 we find large amplitudes of the sleepers between 50 and 125 Hz as well. The excitations of Fig. 2 are acting at these frequencies as well, such that resonance results. But the considerable lowering above the frequency of 125 Hz can not yet be explained. As we find high frequency movement of the sleepers and track elements with large displacements, the mode in 7C with roughly 115 Hz is striking. There the sleepers are interacting with the brake discs even beyond the direct influence of the wheel set where the soft rail pads of the unloaded track are located. The maximum displacement of the sleepers in the unloaded area is about 60% of the brake disc displacement. Comprehensive research shows that wheel set, rails and sleepers are swinging together in same direction at frequencies between 50 and 115 Hz. Above 115 Hz the sleepers are moving increasingly independent Fig. 7: 8 spatial modes of the ICE 1 wheel set on the ballasted track, in which elements of the wheel set have the greatest displacement. Track section 975 cm long. Schwellenabstände = sleeper distances [cm]
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