Date of Award

11-2017

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Graduate Studies

Committee Chair

Dr. Daewon Kim

First Committee Member

Dr. Sirish Namilae

Second Committee Member

Dr. Marwan Al-Haik

Abstract

Carbonnanotube basedhybrid nanocomposites are known to exhibit remarkable electrical and mechanical properties with many potentials in strain and damage sensing applications. In this work, we fabricate hybrid nanocomposites with carbon nanotube (CNT) sheet and graphene nanoplatelets (GNP) as fillers with epoxy matrix. An improvement in both electrical conductivity and piezoresistivity is observed with the combination of CNTs and GNPs, indicating the formation of efficient hybrid conductive networks for strain and electrical transfer in the material. Different matrix materials have been compared to investigate the effect ofmatrixand to choose the one that yields increased strains, flexibility, and electromechanical response. The electromechanical behavior of the hybrid composites is investigated both under static and dynamic loading at various frequencies with induced levels of strains, and has shown positive response under all tested conditions. Digital image correlation has been used to investigate the strain variation within the specimen both during static and dynamic testing. As these sensors will be tested for damage sensing in space applications for inflatable habitat under Micrometeoroid and Orbital Debris (MMOD) impact, the sensitivity of the sensor with 3 mm impact holes is evaluated usingfour pointprobe electrical resistivity measurements. An array of these sensorswhen sandwiched between soft good layers in a space habitatcan act as a damage detection layer for inflatable structures. A computer program is developed to determine the event of impact, its severity and the location on the sensing layer for active health monitoring. Outgassing testing has been performed to evaluate the Total Mass Loss (TML) of the nanocomposite in space environment. Our results indicate that these hybrid nanocomposites exhibit a distinct piezo resistive response which can be beneficial for potential strain, vibration, and damage sensing applications.

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