Machine augmented composite materials for damping purposes

by McCutcheon, David Matthew

Abstract (Summary)
In this study the energy dissipation performance of machine augmented composite

(MAC) materials is investigated. MAC materials are formed by inserting simple

machines into a matrix material. In this work the machines take the form of fluid filled

tubes, and the tube cross-sectional geometry induces fluid flow when it is deformed in its

plane. This flow dissipates mechanical energy, and thus provides the composite material

with attractive damping properties. The objective of this study is to gain insight into the

geometry, the material property combinations, and the boundary conditions that are

effective in producing high damping MAC materials. Particular attention is given to

tube geometry and to dimensionless parameters that govern the energy dissipation

efficiency of a MAC lamina. An important dimensionless parameter is the ratio of solid

elastic moduli to the product of the driving frequency and the fluid dynamic viscosity.

This is a measure of the ratio of elastic forces in the solid material to the viscous forces

in the fluid material that makes up a MAC lamina. Governing equations and simulation

methods are discussed. Simplified equations are derived to predict the pressure

generated when a tube/matrix cell is squeezed with zero pressure end conditions.

Transient, three dimensional finite element models are also used to predict the

performance of the damping MAC materials with zero pressure at the ends of the tubes.

For the geometry and material properties considered, the highest energy dissipation

efficiency predicted by these models is approximately 0.8 out of a maximum of 1.0.

Bibliographical Information:

Advisor:Reddy, J. N.; Creasy, Terry; Perry, William

School:Texas A&M University

School Location:USA - Texas

Source Type:Master's Thesis

Keywords:machine augmented composites damping


Date of Publication:12/01/2004

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