Magnetic Induction Tomography for Non-destructive Evaluation and Process Tomography

Abstract

Magnetic induction tomography (MIT) is an exciting yet challenging research topic. It is sensitive to all passive electromagnetic properties, and as such it has great appeal to many industries. This thesis presents an experimental investigation of MIT within two broad ar- eas of application: non-destructive evaluation (NDE) and industrial process tomography.Within both areas, MIT is presented as a low cost and non-invasive inspection tool with considerable developmental potential with regard to commercial applicability. Experi- mental investigations into the use of MIT demonstrate its versatility in imaging conduc- tive substances ranging from metallic structures, such as pipelines (s ⇡ 106 108S/m) to new composite material, such as carbon fibre reinforced polymers (s ⇡ 104 105S/m), as well as substances in a state of flow (s < 10S/m).Research innovations presented in this thesis constitute (i) the first experimental evalu- ation of MIT for pipeline inspection, an application never before attempted in the area of NDE, (ii) the development of a novel limited region algorithm, which can improve the traditional resolution from 10% to 2%, (iii) the first experimental 3D planar MIT study for subsurface imaging, which opens many opportunities for MIT as a limited access tomog- raphy technique, (iv) an in-depth experimental evaluation of the MIT system response towards various fluid measurements for the first time, while also reporting some of the first flow rig tests in this field.In addition, for each specific application, the capabilities of the prototype MIT systems are assessed with regard to (v) their flexibility in accommodating different sensor geometries, including circular, dual planar, planar and arc, (vi) situations in which the imaging subject has limited access, and (vii) their capacity to reconstruct a viable image of the subject given limited measurement data.Altogether, the results provide an evidential basis for future exploitation of this tech- nique. From the experimental investigations, it is concluded that the major limitations of this technique lie in both the hardware development in order to meet the standards of widespread commercial applications and the software capability for fully automated real time image reconstruction and structural analysis of the imaging subject. Nevertheless, with consistent development in both aforementioned areas, MIT could eventually be used as a rapid NDE technique for structural health monitoring and process tomography, as such contributing both to the social economy and public safety.

Date of Award	21 Oct 2014
Original language	English
Awarding Institution	University of Bath
Supervisor	Manuchehr Soleimani (Supervisor)