Date of Award

12-1-2010

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Abrate, Serge

Abstract

The main focus of this research was to gain an understanding as to how waves propagate through structures. Lamb's Problem was studied on an isometric half plane, where numerical results were obtained. The calculated wavefronts for this problem were in agreement to the numerical results. When a distributed pressure is applied on an isometric half plane, after a long period of time, the wavefronts look as if a point force was applied on the half plane. Waves propagating through an orthotropic material were obtained numerically; it was found that Huygens' Principle cannot be used to calculate the wavefronts. The impact of spherical and cylindrical projectiles on glass plates was studied next. The waves introduced into the material were calculated using Finite Element Analysis, and compared to calculated wavefronts using Snell's Law, where they were found to be in agreement with one another. The effects of circular and square discontinuities were also studied, where a creeping wave that is produced after a wave propagates past a circular hole is explained. A sandwich beam was also modeled using FEA, where the wavefronts were obtained, and were found to be in agreement with calculated wavefronts. The displacement of the bottom layer of the sandwich beam was obtained numerically; it was found that the bending of the beam occurs at the same time as whether the middle layer is present or not.

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