Date of Award

Spring 2026

Document Type

Open Access Dissertation

Department

Mechanical Engineering

First Advisor

Lingyu Yu

Abstract

Non-destructive evaluation (NDE) and structural health monitoring (SHM) have experienced significant growth in both capability and utility as material evaluation and damage detection methods for structural components throughout various industries over the past two decades. Evaluating a structure throughout its life cycle or on demand as needed can identify critical weaknesses that impact safe operation and may prevent failures. Various NDE/SHM methods have been shown to be effective; among them, guided ultrasonic waves (GUW), particularly Lamb wave-based methods, have been intensively studied due to their capability to interrogate internal defects and their relatively larger coverage. With the advancements in new NDE/SHM transducers, sensors, and equipment, as well as data analysis methods, new challenges and needs arise for guided ultrasonic wave-based NDE/SHM. On the system development side, the need for non-contact or remote means to excite or sense the waves has emerged. This work examines the development of a wideband laser-based GUW-NDE and SHM system, utilizing a pulsed laser for remote GUW generation and a scanning laser Doppler vibrometer for surface motion sensing. Focusing first on GUW inspection of isotropic material structures, this is achieved through a combination of fundamental studies and experimental explorations of wave behavior in both very thin (less than 1 mm) and thick (greater than 16 mm) materials, both with and without curvature. The next point of focus is the laser-based NDE/SHM of anisotropic material structures, achieved through a fundamental study and experimental exploration of various sample geometries.

Rights

© 2026, Andrew Philip Campbell

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