More advanced eddy current testing methods

Abstract

As with flux leakage (section 3.6) and many other NDT methods, the eddy current technique lends itself readily to automatic testing, often involving the use of a computer to locate and monitor the positions of the probes and to process the data collected by them; both the speed and reliability of the testing are thereby increased. A simple example is the high-speed rotating probe used for testing defects in tubes. The probe coil is located at the end of a diametrical beam or on a cylinder which rotates by electrical propulsion around the tube axis and follows a helical path as it progresses through the tube in a corkscrew manner. This device can also be used to test for surface defects in fastener holes such as those located in aircraft bodies (Figure 6.1).