Report on a railway Benchmark simulating a single wheelset without friction impacting a rigid track

The new benchmark, which is the focus of this report, uses a single unsuspended wheelset loaded with a constant vertical force, running on an idealized frictionless and rigid perfect track (the call for simulations and full problem description were announced at the Long Beach Railway Symposium in September 2005). The elimination of wheelset suspension avoids the need for calculating sprung mass response and its corresponding contribution to wheel rail contact. Similarly, the idealization of track as frictionless and rigid eliminates the compounding effects of factors such as tangential forces and track response on wheel rail contact. While in principle it could have been possible to isolate treatment of wheel rail contact using quasi-static calculations, the proposed benchmark was deemed more beneficial to allow for the inclusion of simulation codes that exclusively utilized rigid contact and to gage the influence of dynamic variations. It was expected to find different force results due to differences in coding assumptions. In addition, differences in wheel/rail impact forces that otherwise could seem negligible are expected to produce displacement bifurcations. Results suggest that codes using elastic contact appear to be more consistent at predicting derailment resulting from the conditions in this benchmark. This may further suggest that these conditions may be more challenging to predict using rigid contact.