Short-pitch rail corrugation: A possible resonance-free regime as a step forward to explain the “enigma”?

Rail corrugation has been noticed at least for 100 years, but (particularly short pitch one in the range 20–80 mm) has been considered an enigma because measured corrugation wavelength did not relate well with wear-instability models. The apparently large number of governing parameters has resulted in many independent efforts to generate models, which do not entirely correspond to the collected experimental evidence, and therefore there is still some uncertainty over the possible critical factors dominating the phenomenon. We show in the paper that there is a simple possible mechanism of corrugation in longitudinal direction, apparently not noticed before in the literature by other authors, which does not necessarily correspond to a resonance in the system, not even the pinned–pinned resonance associated with the effect of discrete supports, but may depend on geometrical and loading conditions (normal load, creepage ratio, shape of the contact area, etc.), in general overall agreement with experiments. Additionally, some approximate calculations including discrete supports, using a typical concrete sleepers vertical receptance of BR use, show no evidence of corrugation mechanism at the pinned–pinned resonance, at least in the longitudinal direction. A full comparison between lateral and longitudinal mechanisms would depend on the particular value of the lateral creepage vs. longitudinal creepage, system-specific. The present “resonance-free” mechanism is a possible alternative for the data which fall outside the pinned–pinned resonance range