New NDE perspectives with magnetoresistance array technologies – from research to industrial applications

Advances in magnetic sensors theoretically compensate for the major drawback of eddy current techniques for deep-lying defects detection. One solution, based on magnetoresistance arrays, is tested on industrial samples for experimental validation and inspection system characterisation. The intrinsic advantages of the array sensor come from the summation of each of its sensitive elements, which are, independently, electronically controlled. The overall result is high field dynamic performance, high linearity, high spatial resolution, high reproducibility, low magnetic noise and possible adaptation to some specific local sensitivities of the test-piece. The high spatial coverage comes from the juxtaposition of multiple sensitive elements, with almost no limit in size and preferential direction of sensitivity. The description enhances important integration potentials for industrial application, for plane and curved shapes surfaces, from small to large defects, surface or deep lying, in ferromagnetic or diamagnetic structures. The high level NDE performance of the acquisition system are demonstrated on real industrial applications (usually not attained with standard eddy current systems). Furthermore, this approach compensates some of the NDE difficulties encountered with arrays, particularly with the low lift-off influence. In this way, a new array sensor system for industrial NDE is presented. Its performance is tested. Advantages of the technique are highlighted.