PSI - Issue 4

David Simunek et al. / Procedia Structural Integrity 4 (2017) 27–34 D. Simunek/ Structural Integrity Procedia 00 (2017) 000 – 000

28

2

1. Introduction

This paper presents results of experimental investigations of 1:3 scale rotating bending specimens of railway axle material EA4T (EN 13261 (2009)) compared to equivalent results of standardized small-scale single edge notch bending (SEB) and tension (SET) specimens and full-scale specimens, which are part of the current research project “Eisenbahnfahrwerke 3 (EBFW 3), see Deisl et al. (2014) and Gänser et al. (2015). The investigations are primarily based on the previous research project “Eisenbahnfahrwerke 2 ” (EBFW 2) ‘ Safe and economic operation of running gears ’ (see Lütkepohl et al. (2009), Luke et al. (2010) and Luke et al. (2011)). In Zerbst et al. (2013), assessment methods for railway axles are summarized and provide an overview of failure scenarios. The tests in this work act as a link for transferability of material parameters, determined on SEB specimens with different crack front geometry, to full-scale railway axles. Investigations are focused on constant amplitude testing and crack closure effects due to overloads. Evaluation methods are based on previous work of Maierhofer et al. (2014) and upgraded. The 1:3 scale rotating bending specimens are tested by the aid of a four-point rotary bending machine. An optical crack length measurement system documents crack growth on the surface during testing. Surface fracture analyses after testing help to estimate the behavior of the crack front in depth compared to the surface. Figure 1 illustrates the overall design of the experimental investigations in the EBFW 3 project.

Fig. 1 Overall experimental design for assessing geometry and size effects

The motivation and scientific aims of this paper can be summarized to the following working topics:

 Transferability of material parameters from laboratory specimens to full-scale railway axle  Investigations of crack growth at constant amplitude loading and effects of overloads  Determination of the crack front shape (a/c-ratio) at crack propagation

Nomenclature a 0

Depth of semi-elliptical starter notch Semi major axis of starter notch

c 0

CA

Constant Amplitude

D

Diameter of axle or specimen