Masters Theses

Abstract

Nondestructive testing and evaluation (NDT&E) encompasses a range of inspection techniques that assess materials, components, and structures while maintaining their integrity and performance. Among these techniques, thermography is particularly attractive due to its non-contact imaging approach with easy-to-interpret results. Active Microwave Thermography (AMT) has emerged as a promising NDT&E inspection technique that utilizes electromagnetic energy to heat materials through dielectric and magnetic absorption, with subsequent infrared imaging used to detect subsurface defects. While AMT offers significant advantages including material-specific heating optimization and lower power requirements compared to conventional thermographic methods, the technique faces a persistent challenge related to the thermal excitation that is realized by a radiating antenna. Practical antennas radiate a spatially non-uniform power density which translates to a non-uniform heating pattern. This subsequently creates heating artifacts that can mask genuine defect indications or generate false positive results. To address these limitations, advanced post-processing methodologies are needed. To this end, this thesis presents the development of a novel post-processing methodology referred to as Edge Enhanced Phase Analysis (EPA). The EPA approach integrates established edge enhancement filtering techniques (Sobel edge detection, Laplacian of Gaussian (LoG), and Thermal Embossing) with Phase Analysis (PA). Experimental validation demonstrated substantial improvement in defect detection and quantification, with average qualification error reduced from 17.6% for PA only to 6.09% using EPA.

Advisor(s)

Donnell, Kristen M.

Committee Member(s)

Zawodniok, Maciej Jan, 1975-
Watkins, Steve Eugene, 1960-

Department(s)

Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2025

Journal article titles appearing in thesis/dissertation

Paper I: found on pages 19–51, is under review for publication in the IEEE Transactions on Instrumentation and Measurement.

Pagination

x, 60 pages

Note about bibliography

Includes_bibliographical_references_(pages 57-59)

Rights

© 2025 Douglas Blaine Fleetwood , All Rights Reserved

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12566

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