TRACK SYSTEMSSUPPLEMENT 07 The industry is therefore in need of


innovative and advanced systems of inspection that can quickly perform a full volumetric flaw assessment of an AT weld. The RAILECT project was created in response to this demand to bring


Union’s Framework 7 Programme (Project No: FP7-SME-2007-1-222425). The main objectives of the project were to: a)


develop an advanced, innovative, rapid and operator friendly ultrasonic system for the inspection of welds, and b) to establish acceptance criteria for detected flaws so that they could be implemented into the system. The prototype system was developed so that it could fit the CEN 60E1 rail profile, which is the most recent and commonly used European rail profile. The RAILECT system uses phased array


FIGURE 2 Schematic of single ultrasonic phased array probe on rail head showing inspection beam coverage and sweep capability


together rail infrastructure managers, academia, a research organisation, inspection companies, and ultrasonic equipment manufacturers to implement the RAILECT inspection system. The project was partly funded by the European


ultrasonic technology to penetrate, examine and assess the welds. Phased array is an advanced and relatively new technology which has been progressing very quickly over the past few years. Instead of using single element transducers, as in conventional ultrasonics, the phased array technique operates with transducers that contain a number of separate elements in a single housing. The use of multiple elements makes the technique very advantageous compared to conventional ultrasonics as it allows beam focusing and beam steering capabilities.


immediately which is a considerable advantage compared with the systems currently in use in the industry.


a)


b)


FIGURE 5 Fatigue tested samples a) crack at web to base corner, b) crack at foot of rail


One of the innovative aspects of the RAILECT


system was the provision of additional information to the inspector of the AT weld other than the shape and size of the flaw, namely information on the flaw’s severity, so that a


FIGURE 4 Schematic representation of the RAILECT ultrasonic phased array inspection coverage of a rail


The RAILECT device consists of a clamping


mechanism incorporating probe holders, multiple phased array transducers and a computerised instrument for signal processing. The RAILECT instrumentation is easy to transport along the rail track, while the mechanical clamping device allows rapid positioning of the probes onto the rail at specific locations, thus allowing a full volumetric inspection of the rail. It is capable of performing a full assessment of the weld in less than 20 minutes. Defective welds containing flaws such as porosity, shrinkage or lack of fusion (considered as critical indications in AT welds) can be quickly identified. By using the phased array beam focusing


FIGURE 3 RAILECT clamping mechanism and signal processing equipment (top), field testing (bottom).


capability, the inspection resolution is improved and a display of the rail cross-section is produced giving an estimate of the flaw size. This can be compared directly with acceptance criteria to sentence the weld


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FIGURE 6 FEA model of semicircular crack at the foot of a rail, positioned 30mm from the centreline


decision can be made on whether it requires immediate remedial action, or intervention at a later stage, say, during scheduled maintenance. Due to the complexity of the loading and the


shape of the rail, the most common approach to assess the severity of a flaw is to use computer numerical analysis tools such as finite element (FEA) or boundary element (BEA) analysis. This is


European Railway Review Volume 18, Issue 2, 2012


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