Date of Award

Spring 3-28-2024

Access Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Daewon Kim

First Committee Member

Sirish Namilae

Second Committee Member

Yizhou Jiang

College Dean

James W. Gregory

Abstract

Structural health monitoring in plate-like simple structures using phased array beamsteering of guided Lamb waves is useful in damage detection and evaluation efforts. Lamb waves can be effectively used for beamsteering using a linear array. The experimentation primarily focuses on beamsteering in the aluminum panel, which involves developing a simulation based on extracted data to visualize the dispersion of waves across the panel. By evaluating parameters such as slowness, velocity, and amplitude direction and variation for a specific metallic plate, the wavefront generated by a single wave source can be represented as a function of propagation angle and distance from the origin. Using the aluminum panel as the baseline for an established process, the same methodology is extended to the quasi-isotropic panels, where both the Additive Manufactured and conventional composite laminates have a layer sequence of [45/-45/90/0]s. Given the inherent anisotropy of composite materials, the propagation of guided waves varies with direction, resulting in a non-circular wavefront. The time delays for the composite cases are experimentally determined based off the algorithm developed for aluminum cases. Anisotropic waveforms can be effectively utilized for beam steering in specific directions with a linear piezoceramic array, achieving performance comparable to the isotropic case.

Additional testing was completed with a simulated crack in the plate. Using the same experimental methods, a 3D model was created showing the refraction of the wave at the point of damage. This additional testing demonstrates the success and usefulness of the linear PZT array in structural health monitoring and damage detection methods.

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