A new imaging approach for in situ and ex situ inspections of conductive fiber–reinforced composites by magnetic induction tomography

Abstract

Fiber-reinforced plastics for industrial applications face constantly increasing demands regarding efficiency, reliability, and economy. Furthermore, it was shown that fiber-reinforced plastics with tailored reinforcements are superior to metallic or monolithic materials. However, a trustworthy description of the load-specific failure behavior and damage evolution of composite structures can hardly be given, because these processes are very complex and are still not entirely understood. Among other things, several research groups have shown that material damages like fiber fracture, delamination, matrix cracking, or flaws can be discovered by analyzing the electrical properties of conductive composites, for example, carbon fiber-reinforced plastics. Furthermore, it was shown that this method could be used for structural health monitoring or nondestructive evaluation. Within this study, magnetic induction tomography, which is a new imaging approach, is introduced in the topic of nondestructive evaluation of carbon fiber-reinforced plastics. This non-contacting imaging method gains the inner spatial distribution of conductivity of a specimen and depicts material inhomogeneity, like damages, not only in two-dimensional images but also in three-dimensional images. Numerical and experimental investigations are presented, which give a first impression of the performance of this technique. It is demonstrated that magnetic induction tomography is a promising approach for nondestructive evaluation. Potentially, it can be used for fabrication quality control of conductive fiber-reinforced plastics and as a structural health monitoring system using an integrated or superficially applied magnetic induction tomography setup.

Magnetic induction tomography methods and applications: a review

“…As the carbon fibres in CFRPs exhibit electrical conductivity, MIT could be a potential NDE technique providing a tomographic approach to traditional eddy current testing. This was verified in [72] where damages in carbon fiber-reinforced plastics were experimentally investigated. Another 3D experimental study has also demonstrated that images of one or more hidden defects inside CFRPs can be reconstructed, although differences in defect size (15 and 25 mm diameter holes within CFRP layers) could not be distinguished [73].…”

Experimental evaluation of conductive flow imaging using magnetic induction tomography

“…In a typical 2D phantom study case, the cross-sectional images of the properties of the object can be reconstructed using the voltage or phase measurements collected from the inductive coils. Because of the non-hazardous, non-invasive and contactless natures of MIT, its use has been proposed for numerous applications, including foreign material monitoring [1], geological exploration [2], non-destructive evaluations [3,4,5], and biomedical imaging [6,7,8,9,10,11,12,13,14].…”

Hidden defect identification in carbon fibre reinforced polymer plates using magnetic induction tomography

“…Many non-destructive evaluation (NDE) techniques have been applied in this area to CFRP, including low frequency vibration [1], ultrasonic methods [2][3][4][5], radiography [6][7][8], thermography [9,10] and eddy current testing [11][12][13][14]. More recently, soft field tomography techniques have also been used for damage detection in CFRP using electrical impedance tomography (EIT) [15][16][17]; however, magnetic induction tomography (MIT)-based research in this area remains very limited [18].…”