Rectangular Coil Excitation Nondestructive Testing Technique

The alternating current field measurement (ACFM) technique is based on electromagnetic principle and is a kind of the electromagnetic non-destructive testing (NDT) techniques newly developed in these years. In this paper, the status and the development home and abroad of the electromagnetic NDT are illustrated. The basic principle is discussed and the mathematical model is built up. The system scheme for testing is presented. After analyzing the characteristics, both the single rectangular coil probe and compound rectangular coil probe are designed, the advantage and disadvantage are analyzed. Based on the probe mentioned above, a kind of signal source and practicing circuit are designed. Programming the software for testing, realizing the lock-in amplifer with software method and achieving good effect. Realizing the system for testing and inspecting the flaw with it in the plate, the data is analysed.In the end, the conclusions are all given out and the suggestions about the further study are made.