Guided wave mode conversion behavior and delamination detection in composite plates: an FEM-driven approach
Open Access
- Author:
- Yener, Devren Adem
- Graduate Program:
- Engineering Science and Mechanics
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- December 12, 2018
- Committee Members:
- Joseph Lawrence Rose, Thesis Advisor/Co-Advisor
- Keywords:
- ultrasound
ultrasonic
guided waves
composites
delamination
finite element
non-destructive testing
non-destructive evaluation
structural health monitoring
ndt
nde
shm
lamb waves
laminate
carbon fiber
fem
fea
composite - Abstract:
- Ultrasonic guided waves have shown promise for use in the non-destructive evaluation and structural health monitoring of composite laminate materials. However, it can be challenging to find an appropriate strategy for guided wave mode selection and feature analysis to identify defects in composites, due to the complicated material properties of these structures, and the mathematical complexity of the guided wave behavior. In this thesis, we focus on the detection of delaminations in composite laminate plates. We perform a finite-element modeling simulation to gain new and detailed insights into the theoretical behavior of guided waves in the presence of a delamination. We evaluate two commonly-used guided wave mode selection criteria in light of the FEM results, and we propose a third criterion that appears to be more generally valid, namely, that the guided wave mode sensitivity to a delamination depends on the mode conversion and group velocity within the two partial waveguides above and below the delamination interface. Correspondingly, based on a threshold analysis, we identify a useful guided wave signal feature for delamination detection, namely, the peak arrival time of the transmitted wave. We perform an experiment to partially validate these FEM-driven predictions, and we outline a variety of possible avenues for future research and application of this work.