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AUTOMATIC LASER ULTRASONICS FOR RAIL INSPECTION - page 3 / 8

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Inspected rail profile and detectable defects: LURI was developed and tuned to inspect rails of the European profile UIC 60. The dimensions of this profile are: 172 mm in height, 72 mm of running surface width and the weight is 60 kg/m. However, by minor changes of the mechanical design and the ultrasonic data processing software the LURI system can be used with other types of railroad rail profiles. LURI was tested on the following types of structural defect types according to the International Union’s of Railways (UIC) convention:

  • UIC Code 211 – progressive transverse cracking of the head,

  • UIC Code 212 – horizontal cracking of the head,

  • UIC Code 213 – longitudinal vertical crack in the rail head,

  • UIC Code 221.2 – long groove at the running surface,

  • UIC Code 2321 – horizontal cracking at the fillet radius between the web and the

head of the rail,

  • UIC Code 200 – complete vertical (transverse) rail break.

Description of LURI: The system constructively comprises two subsystems positioned on a railroad car, as shown in Fig. 2.: a control subsystem and an optical subsystem. The control subsystem is placed inside the car and includes both the generating and detecting laser systems; the CFPI control and power supply units, data acquisition electronics, as well as several computers for system parameter monitoring, ultrasonic signal processing, and defect finding and identification. The optical subsystem is mounted on a special-purpose, measuring vehicle, which is attached to the bottom of the railroad car. The optical equipment includes the two laser heads, the CFPI with optical detectors, and the auxiliary optics. The optical equipment is mounted on a vibration-insulated platform that is attached to the frame of the mini-car over one of the rails and covered with a dust-tight, moisture-proof shield. The system currently performs one-rail track inspection but may be extended to inspection of both rails. This arrangement of the system allows movement with the speed up to 40 km/h. The adjustment of the system is carried out by means of a number of electromechanical actuators, which control angular and linear displacements of the platform. The beams of the lasers are directed towards the rail by means of inclined mirrors. The generating beam is focused to a line on the surface of the rail. The proper lengths of the generating beam spot as well as two optimal arrangements of the laser spots, which enable best detection of rail defects, have been found by means of comprehensive computer simulation [3] and numerous laboratory and field experiments [2].

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