Extending the Applicability of the Partial Wave Method for Interpreting Waves in Elastodynamic Waveguides
Open Access
- Author:
- Hakoda, Christopher Nobuo
- Graduate Program:
- Engineering Science and Mechanics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 30, 2019
- Committee Members:
- Clifford Jesse Lissenden III, Dissertation Advisor/Co-Advisor
Clifford Jesse Lissenden III, Committee Chair/Co-Chair
Parisa Shokouhi, Committee Member
Francesco Costanzo, Committee Member
Julianna Simon, Outside Member - Keywords:
- The Partial Wave Method
Elastodynamic Guided Waves
Group Velocity
Elastic Waves
Waveguide
Dispersion Curves
SAFE
Mode Sorting - Abstract:
- The term "Partial Wave Method" was coined in the 1970s but the underlying concept has been around for much longer. At its foundation, the method describe show the Christoffel equation solutions (i.e., partial waves) can act as the basic building blocks of most, if not all, elastodynamic guided waves. In particular, the method has been praised for its ability to afford researchers further insight into the characteristics of guided waves. However, even with these benefits and apparent importance, literature on the subject is relatively scarce. In this dissertation, we have done our best to add to this portion of the literature by looking closely at the relationships between guided waves and their partial wave compositions. We compare the likeness of half-space-related waveguides and finite-sized waveguides through the perspective of the Partial Wave Method and discuss the transition from one to the other. We use the Partial Wave Method to explore the use of acoustic leakage for measuring the wavenumber spectrum of guided waves. We demonstrate limited mode sorting of guided waves in an isotropic plate, and use slowness curves to inform our understanding of different regions in the dispersion-curve space. Lastly,we analyze the apparent discrepancy between the partial waves’ group velocity and the guided wave’s group velocity. The objective of this dissertation is to use the Partial Wave Method to improve our conceptual understanding of guided waves and to look at familiar tools, either experimental or numerical, from a different perspective. Given the diversity of topics and relevance to fundamental concepts,we hope that it will be an informative reference for those studying elastodynamic guided waves.