Some comments on surface cracks in rails |
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| Authors: | F D FISCHER W DAVES R PIPPAN P POINTNER |
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| Affiliation: | Institute of Mechanics, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700 Leoben, Austria and Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstrasse 12, A-8700 Leoben, Austria and Materials Center Leoben, Austria;;Materials Center Leoben, Franz-Josef Strasse 13, A-8700 Leoben, Austria;;Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, and Christian Doppler Laboratory for Local Analyses of Deformation and Fracture, Jahnstrasse 12, A-8700 Leoben, Austria;;Voest Alpine Schienen GmbH &CoKG, Kerpelystraße 199, A-8700 Leoben, Austria |
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| Abstract: | The present work considers the problem of whether a shallow angle surface crack on a rail may propagate either parallel or perpendicular to the surface. After referring to a classification of crack‐like defects, a distinct surface crack with a typical length of 1 mm and more, inclined to the surface by an angle of approx. 30°, is introduced. Then various strain and stress states are discussed (eigenstress, residual and load stress state) which may control the crack growth. Stress intensity factor equations are provided for the internal and load stress states. In particular, the deformation process due to a single pass (overrolling) by a wheel is investigated. Recommendations are presented on how to relate the stress intensity factor ranges to the actual deformation process. For a typical loading condition, the positive part of the mode I stress intensity factor range is near to the effective threshold value of a rail steel. The influence of the material and its strength on the crack propagation behaviour is discussed qualitatively. |
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| Keywords: | crack propagation eigenstress state load stress state rail rail surface crack residual stress state stress intensity factors |
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