Spannungsintensitätsfaktoren für Risse in Schienen

Abstract

KurzfassungEisenbahnschienen können unter Betriebsbedingungen brechen. Mit Hilfe der Bruchmechanik lassen sich das Risswachstums- und Bruchverhalten der Schienen untersuchen. Um dieses Verhalten z.B. im Hinblick auf die zerstörungsfreie Prüfung der Schienen im Gleis analysieren zu können, müssen die folgenden Einzelheiten bekannt sein:Betriebs- und Bruchbedingungen (Schienentyp, Radkräfte, Biegemomente, Temperaturen, Normalkräfte und Eigenspannungen),die bruchmechanischen Eigenschaften des Schienenstahls unter Betriebsbedingungen,die Form der Risse und die entsprechenden Spannungsintensitätsfaktoren.Für Schienen des Typs R65 sind die Spannungsintensitätsfaktoren für Querrisse, die von der Fahrfläche ausgehen, mit dem FEM-Programm ANSYS berechnet worden für die radkraftbedingte Biegung, für Temperatur-Normalkräfte sowie für die Längseigenspannungen.

Some comments on surface cracks in rails

“…As a partial conclusion, one must distinguish between a situation where a positive eigenstress state in the amount of σ r = 150−175MPa exists after straightening and overrolling for low loads and traction and the situation of heavy loading and traction with σ r being a compressive stress at the level of –250 MPa. This value is of the same magnitude as reported by Boudnitzki et al ., 2 namely –175 MPa, for heavily loaded Russian rails. A final remark may be of interest about the effect of a series of parallel surface cracks as they may appear in the case of ‘head checks’.…”

“…To the knowledge of the authors, the most comprehensive literature review can be taken from the reports in Refs. [1–3]. The team of Prof. Edel 2 reports on classification of diverse crack‐like defects, edited by various organizations, distinguishing approximately 15 to 40 different types of crack‐like defects.…”

“…[1–3]. The team of Prof. Edel 2 reports on classification of diverse crack‐like defects, edited by various organizations, distinguishing approximately 15 to 40 different types of crack‐like defects. Here rolling contact fatigue cracks (RCF cracks), growing from microcracks generated in the deformed surface layer of the rail head, are considered.…”

Fatigue crack initiation life prediction of railroad

“…These are tensile stresses at lower and compressive stresses at higher temperatures. Due to Boudnitski and Edel [15] most European rail failures occur at temperatures at or slightly above . At this temperature high tensile thermal stresses are combined with relatively low toughness values of the rail materials.…”

Introduction to the damage tolerance behaviour of railway rails – a review

“…Other transverse crack types such as straight and semi-elliptical surface cracks in the rail head (c and d) and in the rail foot (f) and corner cracks at both sites (b, g, d) have also been investigated (e.g. [101][102][103][104]). Besides the transverse crack geometries shown in Figure 55, further crack configurations such as web cracks induced by bolt holes and weldments, vertical axial rail head cracks (splits) and cracks in switches have been investigated as well [105][106][107][108][109][110][111].…”