Date of Award

3-9-2009

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Anthony N. Palazotto, PhD

Abstract

Typically turbine engine blades gain protection from thermal damage by the use of hard coatings, such as magnesium aluminate spinel. Known as Thermal Barrier Coatings (TBC's), they have material properties that include several nonlinearities. These TBC's create damping primarily due to their nonlinear dissipation of energy. In order to effectively represent their damping properties, it is necessary to create a method which combines experimentation and analysis. Previous work has shown the need for a beam bounded and loaded in such a fashion that external support energy dissipation functions i.e. boundary conditions and aerodynamics are eliminated. Thus, a new experimental apparatus and method was used to determine the nonlinear material properties of these materials. Investigators incorporated monofilament wires and magnets, along with linear assumptions, to approximate free-free boundary conditions. This allowed the non-linear damping properties of these materials to be approximated. This research included finite element analyses specifically created to put bounds on the experimentally developed material properties. Since prior work never established ranges of effective properties, the question that was addressed was how far off can a relationship be before it changes the overall result. Thus, this research varied several material parameters as well as experimental boundary conditions to evaluate their effect on the damping coefficients such as the loss factors as well as the material modulus.

AFIT Designator

AFIT-GA-ENY-09-M03

DTIC Accession Number

ADA496120

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