Date of Award

Spring 2026

Document Type

Open Access Dissertation

Department

Mechanical Engineering

First Advisor

Sourav Banerjee

Abstract

Ultrasonic guided waves are widely used in nondestructive evaluation (NDE) and structural health monitoring (SHM) for detecting defects and damage in engineering materials and structures. Conventional diagnostic features, such as attenuation of wave amplitude, shifts in time-of-flight, and frequency variations are widely used for damage identification. However, these metrics are inherently sensitive to environmental and operational variations, including temperature, pressure, humidity, sensor coupling conditions, boundary constraints, and external loading. Such sensitivities introduce significant uncertainty in signal interpretation, often obscuring damage-related signatures. Recent advances in wave physics have revealed that elastic guided waves exhibit intrinsic spin angular momentum (SAM), arising from the local polarization and phase relationships of displacement fields. In structured waveguides, the interplay between spin and orbital angular momentum gives rise to phenomena such as spin-momentum locking, spin–orbit interactions (SOI), and geometric (topological) phase accumulation.

This dissertation investigates the quantum-like spin behavior of elastic guided waves and its direct connection to geometric phase accumulation, with the objective of developing robust, physics-informed features for NDE and SHM. Within a state-space framework, geometric phase is defined through normalized comparisons of multi-sensor or full-field wave states, while spin characterizes the local rotational motion of particles and serves as the physical origin of phase evolution. Because these quantities depend on wavefield organization and polarization, they exhibit reduced sensitivity to arrival time and amplitude variations, while retaining frequency-dependent characteristics.

The first part of the thesis establishes the fundamental relationship between structural geometry and spin dynamics. Using corrugated waveguides as a model system, it is demonstrated that geometric perturbations induce polarization changes that generate distinct spin textures and drive global geometric phase accumulation. A comprehensive spin framework for guided waves is developed, identifying multiple spin components unique to these systems. Three-dimensional numerical simulations reveal that corrugation alters through-thickness polarization distributions and produces measurable geometric phase shifts relative to a flat-plate baseline, highlighting geometry-driven polarization rotation as a viable sensing mechanism. Building on this foundation, the second part translates geometric phase into an experimental damage characterization tool using a multi-sensor piezoelectric (PZT) network on an aluminum plate. Angle-resolved and radius-resolved analyses demonstrate that geometric phase enables damage detection, spatial localization through characteristic phase fingerprints, and discrimination of damage size, even in cases where traditional response features are non-monotonic. The final part examines the combined influence of tensile loading and damage. A specific frequency band is identified in which geometric phase exhibits weak sensitivity to incremental loading while maintaining strong sensitivity to damage characteristics.

Collectively, this work progresses from fundamental physical insights to experimental validation and practical implementation under realistic service conditions. The results demonstrate that spin and geometric phase provide a robust, physics-based alternative to conventional guided-wave features by leveraging wavefield polarization and spatial organization. This approach reduces dependence on amplitude and time-based metrics and enables damage-sensitive yet load-tolerant monitoring of plate-like structures.

Rights

© 2026, Md Ebrahim Khalil Bhuiyan

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