Magnetic Induction Tomography Spectroscopy for Structural and Functional Characterization in Metallic Materials

Abstract

Magnetic induction tomography (MIT) is a powerful imaging system for monitoring the state of metallic materials. Tomographic methods enable automatic inspection of metallic samples making use of multi-sensor measurements and data processing of eddy current-based sensing from mutual inductances. This paper investigates a multi-frequency MIT using both amplitude and phase data. The image reconstruction algorithm is based on a novel spectrally-correlative total variation method allowing an efficient and all-in-one spectral reconstruction. Additionally, the paper shows the rate of change in spectral images with respect to the excitation frequencies. Using both spectral maps and their spectral derivative maps, one can derive key structural and functional information regarding the material under test. This includes their type, size, number, existence of voids and cracks. Spectral maps can also give functional information, such as mechanical strains and their thermal conditions and composition.

A Review on Magnetic Induction Spectroscopy Potential for Fetal Acidosis Examination

“…Each of the proportioned frequency components has a good compromise between sensitivity at high and low frequencies. [ 80 ]. High-frequency measurements provide information regarding the properties adjacent to the sample surface, while low-frequency measurements sense deeper inside the sample [ 79 ].…”

Multi-Frequency Magnetic Induction Tomography System and Algorithm for Imaging Metallic Objects

“…Although penetration is small at higher frequencies, corrosion is generally a surface effect and therefore detectable [ 24 ]. Muttakin and Soleimani demonstrate metallic material characterisation using spatio-spectral analysis over a frequency range of 100 Hz to 100 kHz [ 35 ]. Complex impedance data from MIT array sensors are used to interrogate a variety of metallic structures, indicating a change in both phase and magnitude, in response to both sensor position and excitation field frequency.…”

Inverse Transformation in Eddy Current Tomography with Continuous Optimization of Reference Defect Parameters

“…It is based on the standard eddy current non-destructive evaluation method [2][3][4][5], where the tested object influences the coupling of at least two coils. ECT (eddy current tomography) setups either collect data from multiple sets of coils [6][7][8][9] or conduct measurements for different positions of the sample [10,11].…”

“…Eddy current tomography has many applications, such as magnetic spectroscopy [9,12] (determining the permeability of a material as a function of measurement frequency), assessing phase changes in matter [13,14], or even assessing changes in the state of biological tissues [15,16]. In this paper, a method for the utilization of ECT in the non-destructive evaluation of objects is presented.…”