Issue << content << Automatic Flaw Detector Channels Sensitivity Adjustment with the Use of an Adaptive Threshold


DOI: 10.12737/21179

2016. Vol.19. No. 3, pp. 77-80

Automatic Flaw Detector Channels Sensitivity Adjustment with the Use of an Adaptive Threshold

V. F. Tarabrin, O. E. Chistyakova, O. N. Kislyakovsky, D. A. Kononov

Introduction. With high-speed total ultrasonic testing (UT) of the rails, the urgent task is to provide the required testing sensitivity under the impact of a significant number of adverse factors caused by the following reasons:
  • unstable acoustic contact;
  • incorrect flaw detector channel settings due to underskilled staff;
  • a misalignment, for example when passing a small radius curve or when rails have significant lateral wear.
The listed factors lead to level changing of echo signals within a wide dynamic range as well as to echo amplitudes ratio changing of useful and noise signals. In contrast to manual testing when an operator has the possibility of multiple scanning, total rails testing by a mobile diagnostic system is fulfilled by only a single scan.
The objective of the work was to develop an optimal algorithm of flaw detector channels sensitivity adjustment and formulate the reasonable requirements for a mathematical model and hardware.
Method. Theoretical researches and experimental work were conducted and resulted in the development of a multichannel flaw detector for inspection of rails by mobile means. The analysis of different mathematical models has enabled the optimal algorithm for automatic channels sensitivity adjustment to be developed.
Results. The developed algorithm has allowed minimizing the impact of the negative factors and compensating the sensitivity to the level that enables high-speed single-scan rails testing to be fulfilled and maximum information at a high level of reliability to be recorded. Implementation of the adaptive threshold principle has made it possible to develop and offer the technique and technology for automatic flaw detector channels sensitivity adjustment.
Conclusion. The offered technique and technology can be fully put into practice with the developed flaw detector and its control software.
 
Keywords: ultrasonic testing,  mobile diagnostic systems, rails, multichannel flaw detector, sensitivity adjustment algorithm
References
  1. Tarabrin V. F., Odynets S. A., Kislyakovsky O. N. V mire NK [NDT World]. 2003, no. 3(21), pp. 74–75 (in Russ.).
  2. Gurvich A. K., Dymkin G. Ya., Koryachenko V. D. et al. Defektoskopiya [Soviet J. Nondestructive Testing]. 1981, no. 3, pp. 107-109 (in Russ.).
  3. Tarabrin V. F., Kislyakovsky O. N., Kononov D. A. V mire NK [NDT World]. 2013, no. 2(60), pp. 66–68 (in Russ.).
 
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