By Anders Johansson

Causes and consequences of out of round wheelsets are investigated through literature studies, full-scale field experiments and mathematical simulations in this thesis, which contains a collection of papers presented for the degree of licentiate of engineering at Chalmers University of Technology.

The literature survey reviews current thinking on the reasons why wheels become out of round, and the resulting damage caused to tracks and vehicles. The focus is on long-wavelength defects around the wheel circumference, including polygonalisation with up to five harmonics.

The influence of different types of out of roundness on wheel-rail contact forces is investigated through mathematical simulations, calibrated with measured responses obtained through extensive field testing. An existing multi-body model of three-dimensional track-train interaction on straight track is extended with rolling contact mechanics, wear models and wheel profiles. Other damage mechanisms than wear coupled with dynamic wheel-rail interaction are also discussed briefly.

Department of Applied Mechanics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.

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