Induction defectoscope based on uniform eddy current probe with GMRs

Defect detection in conductive plates represents an important issue. The present work proposes an induction defectoscope that includes a uniform eddy current probe with a rectangular excitation coil and a set of giant magnetoresistance sensors (GMR). The excitation current, the acquisition of the voltages delivered by the GMR and the signal processing of the acquired signal are performed by a real-time control and processing unit based on a TMS320C6713 digital signal processor (DSP). Different tests were carried out regarding the excitation coil position versus crack orientation and also regarding the GMR position inside the coil and the best response concerning the crack detection for a given aluminum plate specimen. Embedded software was developed using a NI LabVIEW DSP module including sinusoidal signal generation, amplitude and phase extraction using a sine-fitting algorithm and GUI for the induction defectoscope. Experimental results with probe characterization and detection of defects were included in the paper.