Khaleda Akter

Date of Award

Spring 2021

Document Type

Open Access Dissertation


Mechanical Engineering

First Advisor

Sourav Banerjee


Elastic wave propagation in anisotropic media is of great interest in various branches of engineering and applied sciences. In this study, an anisotropic wave propagation behavior in isotropic material with orthogonal surface perturbation is presented. The conventional method of estimating dispersion equations for isotropic material is to apply Helmholtz decomposition on the potential functions for Rayleigh-Lamb wave and Shear Horizontal (SH) waves. However, the presence of isotropic material with orthogonal surface perturbations in two coordinate directions significantly affect the wave propagation behavior due to its direction dependency, and hence, the Helmholtz decomposition of the potential functions cannot be applied to derive the dispersion equations. In this study, a generalized analytical expression for the Rayleigh-Lamb wave propagation in flat plate and a corrugated plate with orthogonal surface perturbation in two coordinate directions is developed by assuming the three potential functions introduced by Buchwald (1961) for anisotropic material. By setting the perturbation height to zero, the dispersion equations are solved using a logical root-finding algorithm for the flat plate and compared them with the results reported in literature. To validate the wave propagation behaviors in isotropic materials with orthogonal surface perturbated corrugated structure, a time domain simulation is performed by the Finite Element Method using a chirp signal to excite the corrugated plate. Finally, the displacements of the particles are obtained in multiple time steps and analyzed for wave propagation pattern at various points on the corrugated structure.