Fast and direct assessing defect dimensions in conductive materials using a double GMR-based eddy current sensor

Purpose This paper aims to evaluate the dimensions of defects in conductive materials using eddy current nondestructive testing (EC-NDT) without the need for inversion models. The approach focuses on a new eddy current sensor based on giant magnetoresistances (GMRs). Design/methodology/approach This work presents a new eddy current sensor based on GMR for evaluating the dimensions of defects in conductive materials without the need for inverse models. An essential aspect of this technique is the use of two GMR sensors placed at the front and rear of a rectangular probe, in the scanning direction. The eddy current rectangular probe is excited by an adequate voltage waveform and frequency. The GMR sensors are particularly sensitive to any variation of the resulting magnetic fields, which makes them excellent for identifying minor imperfections inside the material. The proposed sensor allows to determine precisely the size of defects in conductive materials. Findings The results of this work show that the new proposed double GMR-based eddy current sensor is a cost-effective and noninvasive solution for evaluating the dimensions of defects in conductive materials, without the need for inversion models. Accuracy of defect size assessment is improved by exciting the eddy current rectangular probe with a square-waveform AC voltage. This double GMR-based eddy current sensor offers a simple and effective solution for evaluating the dimensions of defects, providing valuable information for ensuring the quality and reliability of conductive materials. The new proposed sensor offers an accurate, reliable, robust and cost-effective solution for nondestructive testing, with the potential to be widely used in various industrial applications. Research limitations/implications This double GMR-based eddy current sensor is effective for assessing defect dimensions on the surface of materials, but is not as robust for deep defects and micro-cracks. Practical implications One of the major benefits of this double GMR-based eddy current sensor is that it does not require inversion models, making it a straightforward and practical solution. Inversion models are often complex and time-consuming, and they can introduce errors into the results. By avoiding the use of inversion models, this sensor provides a fast and accurate solution for nondestructive testing. Originality/value This research is a contribution to the field of eddy current NDT, specifically in the geometric characterization of defects. The innovation in the proposed double GMR-based eddy current sensor lies in the use of two GMR sensors placed on a rectangular CF probe excited by a square-shaped signal. Its originality lies in the efficiency, robustness and very high accuracy of this new sensor in providing the length of the defect.