The review focuses on sensitivity in ultrasonic flaw detection in rails and related accompanying issues. The set of topics considered includes changes in definitions of terms, used measures and methods of sensitivity adjustment that have occurred over the past 25 years. Amplitude characteristics of detected defect are considered in detail. The article is supplemented with practical examples of sensitivity settings, as well as measurements of signal amplitudes and defect detection coefficient for various cases.
The first experience of remote training of Russian Railways specialists in rail inspection was considered. This modern form of training has proved to be quite effective for improving the qualifications of specialists who already have experience in work. Remote training of beginners is difficult because in a short period of time it is impossible to accommodate a significant amount of necessary knowledge. It is not possible to organize practical classes on setting up and working with flaws and rail samples with various defects. In conclusion, small reviews of the first students are given.
The article is devoted to the question of rail ultrasonic testing confidence. At present there is a range of flaw orientation angles in within which the testing is absent and, therefore such flaws can be lost. To except this drawback the current sound testing scheme in flaw detector railcars is to be supplemented with inclined probes exciting longitudinal wave. Experimental checks using echomethod showed the good results on an October railway section with flaw models and on a loaded Zabaycalskaya railway section. The next step was idea of mirror-shadow method using as well as echomethod by turning of probes towards each other. Envelope analysis of bottom signals allows receiving additional information about flaws: location depth of its center and form. But using of pair of probes was not enough for unambiguous definition of other geometric flaws characteristics. That is why the bottom signal envelope of straight probe was to be analyzed additionally. A mobile (as well removable) searching system of rail checking means has such probe as a rule. In the process of writing the article previously obtained formulas to calculate depth, inclination angle and plane size of revealed flaw were modified. Values changing during testing process are absent now. Algorithm of flaws identification on the basis of bottom signals envelope is given. The approach is confirmed by mathematical modeling in CIVA-UT.
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