Non-destructive testing of critical infrastructure with giant magneto resistive sensors

Abstract

Corrosion is the leading failure mechanism for metallic structures. One of the standard non-destructive techniques to assess the status and predict remaining lifetime and possible failure is based on the excitation with a varying magnetic field and measuring the change of the magnetic field due to eddy currents in the device under test. Since the magnetic field is decaying quickly a large lift-off between the excitation source, magnetic sensors and the test object will reduce the signals considerably. In order to obtain a deep penetration into the test object excitation at low frequency is desirable. In this study investigation of a high power excitation system in combination with giant magneto resistance (GMR) based sensors was done. GMR sensors have a good sensitivity and are suitable for low frequency eddy current testing due to their low 1/f noise. Finite element analysis was used to evaluate the excitation setup, sensor alignment and positions and study the influence of different parameters of the excitation and sensor setup as well as the device under test. Based on these results a laboratory setup was build and used to study the influence of main measurement parameters.

Prospect of Using Machine Learning-Based Microwave Nondestructive Testing Technique for Corrosion Under Insulation: A Review

“…Various conventional NDT techniques are well established in the industry, such as x-ray, thermography, eddy currents, Giant Magneto Resistive (GMR) [16], Scanning Kelvin Probe (SKP) [15], eddy currents [17] and ultrasonic [18]. These techniques can be performed on various structures in terms of conductive and nonconductive materials to evaluate different types of defects such as cracks, delamination, and debonding.…”

“…An NDT technique can evaluate material integrity for surface or subsurface defects or metallurgical conditions without interfering in any way with the destruction of the material or its suitability for service [14]. In the industrial sector, there are several types of conventional NDT techniques that are routinely employed, such as Scanning Kelvin Probe (SKP) [15], Giant Magneto Resistive (GMR) [16], eddy current [17] and ultrasonic testing [13]. These conventional techniques have their benefits and drawbacks in terms of safety, expenditures, processing time, and efficiency of the inspected materials.…”