Application of Inclined Longitudinal Ultrasonic Waves to Improve the Efficiency of Rail Flaw Detection

Abstract

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.