Combination of a GMR sensor and reconstruction algorithm:a novel magnetic sensing system

摘要

Over the past few years, the authors have developed a reconstruction algorithm that can accurately reconstruct images of flaws from data obtained using conventional ECT sensors. The algorithm is simple and fast and involves few steps, thus making it suitable for implementation on a PC. The algorithm can be applied to study eddy current systems; it can also be used in conjunction with non-destructive testing methods involving a magnetic field. However, there is one inherent limitation related to sensor design. In eddy current or magnetic flux leakage, a conventional sensor is used to detect flaws in damaged areas. This sensor is designed in such a manner that when the magnetic field is imposed on the target surface, the strength of the magnetic field is maximized. This measurement method has remained unchanged since the introduction of the technique. The developed reconstruction algorithm is designed for data obtained by imposing a uniform magnetic field on the target surface. Recent developments in computer technology have enabled the integration of computing and testing equipment; in this context, the authors believe that a new sensor for use with reconstruction algorithm will be required. Therefore, the authors have developed a prototype sensor for applications to magnetic flux leakage. The developed sensor comprises a GMR magnetic field sensor to detect a static magnetic field and two magnets adjacent to the GMR sensor to magnetize the target specimen. The results of the combined use of the sensor and the reconstruction algorithm are presented in this paper.