| Summary: | 碩士 === 大葉大學 === 電機工程學系碩士班 === 92 === Ultrasonic Testing (UT) is a major nondestructive testing method , it is widely used in the inspection of steel structures , boilers , piping systems , vessels etc. Hence UT is vital to the safety of most facilities and the public . However , in most cases, the severity of a flaw is mainly judged by its echo height and this has been considered inadequate especially for planar flaws . Because this kinds of flaws are highly undesired it is very important to design a better sizing technique for this application . In this research a novel one is proposed and named RRARC which stands for Reliable Repeating ARCs . During a normal scan , at every probe position when a tip echo is caught an arc can be drawn with the probe position as the center and the echo path length as the radius . Theoretically , these repeating arcs will intersect with each other at the flaw tip which is the center generating those diffraction echoes . Therefore , these intersections can be used to calculate the mean position and its associated error of the flaw tip and this makes this technique not only a reliable one but also technically meaningful .
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