Defect classification using phase lag information of EC-GMR output

Abstract

Eddy current testing (ECT) is an important method in non-destructive testing. Classification of defects is a challenging problem in ECT. In this paper, we propose a method in which the phase lag is adopted, and in order to detect the deep sub-surface defects, giant magneto resistance sensor is chosen to detect the magnetic field influenced by the defects. The phase of the magnetic field intensity is used to help classify the defects. Results from the experiments carried out show that the method is effective.