Date of Award

9-8-2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

Anthony N. Palazotto, PhD

Abstract

Functionally graded material (FGM) plates are advanced composites with properties that vary continuously through the thickness of the plate. Metal-ceramic FGM plates have been proposed for use in thermal protection systems where a metal-rich interior surface of the plate gradually transitions to a ceramic-rich exterior surface of the plate. The ability of FGMs to resist impact loads must be demonstrated before using them in high-temperature environments in service. This dissertation presents a novel technique by which the impact response of FGM plates is characterized for low-velocity, low- to medium-energy impact loads. An experiment was designed where strain histories in FGM plates were collected during impact events. These strain histories were used to validate a finite element simulation of the test. An optimization technique was applied to estimate local material properties in the FGM plate to enhance the finite element simulation. The optimized simulation captured the physics of the impact events. The method allows research & design engineers to make informed decisions necessary to implement FGM plates in aerospace platforms.

AFIT Designator

AFIT-DS-ENY-08-06

DTIC Accession Number

ADA486901

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