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Automated Systems for In-Service Non-Destructive Testing of Railroad Wheels and Axles

: Kappes, W.; Bähr, W.; Salzburger, H.-J.; Walte, F.

16th International Wheelset Congress 2010. Proceedings. CD-ROM : Cape Town 14th - 19th March 2010
Cape Town, 2010
16 pp.
International Wheelset Congress (IWC) <16, 2010, Cape Town>
Conference Paper
Fraunhofer IZFP ()
electromagnetic-acoustic-transducer (EMAT); non-destructive testing

Wheel sets of rail vehicles, especially of high-speed trains, are subject to high dynamic loads. In order to detect possible defects at an early stage the wheel sets have to be inspected periodically applying non-destructive testing techniques. Both wheels and axles have to be checked for material defects.
In close cooperation with industrial partners we have developed methods and equipment for the in-service inspection of wheels and axles in maintenance workshops.
Stationary systems are used to inspect disassembled wheel sets which have to undergo a refurbishment process. The inspection is run after re-profiling the wheels on a lathe and before final assembly of the wheel set. Mobile testing equipment is applied to inspect wheel sets which need no refurbishment. In this case the inspection can be carried out on the train which saves the costly dismantling of wheel sets and is also beneficial in terms of train availability.
A fast and early detection of crack-like defects in the near surface zone of the tread of railway wheels can even be performed while the train is passing over stationary ultrasonic probes at speeds of up to 15 km/h. This system based on the Electromagnetic Acoustic Transducer technique EMAT can inspect all the wheels of a train within a few minutes and allows a fast check of the condition of the tread.
The presentation introduces ultrasonic testing systems for wheels and axles of high-speed train sets as well as combined ultrasonic and eddy-current testing stations for wheel sets of passenger trains and freight cars featuring block brakes.
Special requirements for new installations of the wheel and axle testing systems requests development of state-of-the-art miniaturized front-end ultrasonic and eddy-current test instrumentation. Innovations in that regard offer new dimensions for the concept and design of such wheel and axle testing systems, including features that provide a minimum of effort in maintenance of the inspection systems.
Due to the small size of the electronic modules those can be placed in close proximity to the transducer assembly. High-speed networking techniques ensure the transfer of all the digital ultrasonic and eddy-current data acquired from the front-end modules to the workstation being responsible for data acquisition and analysis.
The paper will give an overview of those systems, describe their function as well as their operability in real customer service and will conclude with some thoughts on lessons learned and possible ways ahead.