Author

Jiukun Li

Date of Award

5-2016

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Graduate Studies

Committee Chair

Dr. Sirish Namilae

First Committee Member

Dr. Daewon Kim

Second Committee Member

Dr. Marwan Al-Haik

Abstract

The unique mechanical and electrical properties of carbon nanotubes and graphitic structures have drawn extensive attention from researchers over the past two decades. The electro-mechanical behavior of these structures and their composites, in which electrical resistance changes when mechanical deformation is applied facilitates their use in sensing applications.

In this work, carbon nanotube sheet- epoxy nanocomposites with the matrix modified with various contents of coarse and fine graphene nanoplatelets are fabricated. The addition of a secondary filler results in improvements of both electrical and mechanical properties. In addition, with the inclusion of the second filler, change in resistivity with mechanical deformation (manifested by gauge factor) is significantly enhanced. Nanocomposite with 5 wt. % coarse graphene platelets achieved is the most effective resistivity-strain behavior and largest gauge factor. Similar trend in variation of gauge factor variation was observed for fine graphene nanoplatelet - nanotube sheet nanocomposites. An analytical model for explaining these observations, incorporating strain and the effect of second filler, is developed.

Sensors fabricated using these hybrid nanocomposites can be potentially used in damage sensing of aerospace carbon-fiber composites.

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