19 th World Conference on Non-Destructive Testing 2016 1 License: http://creativecommons.org/licenses/by/3.0/ Reliability Analysis of the Ultrasonic Inspection System for the Inspection of Hollow Railway Axles Mato PAVLOVIC 1 , Christina MÜLLER 1 , Thomas HECKEL 1 , Andreas ZOËGA 2 1 Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany 2 DB Systemtechnik GmbH, Brandenburg-Kirchmöser, Germany Contact e-mail: mato.pavlovic@bam.de Abstract. Axles are safety critical train components that are subjected to significant cyclic loading during operation. If the crack is initiated in the axle, cyclic loading will lead to crack propagation. To maintain structural integrity, axles must be periodically inspected for fatigue cracks in the material. Deutsche Bahn uses mechanized ultrasonic inspection system to inspect hollow railway axles. The inspections are performed from the bore surface, using several conventional transducers with different incident angles, inspecting the axle along the entire length. As with the every safety critical system, the reliability of these inspections must be determined with regard to their flaw detection capabilities. Traditionally this is done according to the relevant standards for railway vehicles. To investigate the capability of the NDT system more thoroughly, we want to evaluate the capability of the inspection system to detect flaws by means of probability of detection (POD) curves. It will be shown that other parameters, beside the size of the crack, for example crack position in the axle, influence the detection of the crack. The influence of these parameters was evaluated using ultrasonic simulation. The evaluation served as an input for the manufacturing of the flaws in the real scale axle. Once these axles are inspected and the data evaluated, using data from both measurement and simulation, we will express the POD of the crack as function of influencing parameters using the multiparameter POD model. 1. Introduction Railway axles are safety critical components. If, during operation, a crack is initiated in the axle, it can be assumed that it will propagate under the cyclic loading perpendicular to the axis of the axle [1]. For this reason, axles are periodically checked for flaws by means of NDT By trying to detect ever smaller flaws, NDT systems are pushed to their limits, resulting in inconsistent flaw detection. Some flaws of the same size are detected and some are missed. The same flaw, by repeated inspections, will sometimes be detected, and sometimes not. The capability to detect (small) flaws is therefore expressed as the reliability of the NDT system. The probability of detection (POD) curve is a standard tool to express the reliability of NDT systems. The capability of the automated ultrasonic (UT) inspection system to detect flaws in the hollow railway axles is performed according to the standard DIN 27 201 [2]. A system’s acceptability is determined by its ability to detect an artificial flaw (a saw cut) of 2mm depth extension in the axle, with a 6 dB safety margin. However, it has been postulated that these systems can detect much smaller flaws [3]. It has also been shown that saw cuts, as ultrasonic reflectors, are bad representatives of the real More info about this article: http://ndt.net/?id=19530