Yachna Gola

Date of Award

5-2019

Access 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. Feng Zhu

Third Committee Member

Dr. Virginie Rollin

Abstract

Future space exploration requires easy-to-transport, and easy-to-build and deploy space habitats. NASA and Bigelow Aerospace have collaborated so that human habitation can be made safe and easy with inflatable space habitats (Litteken, 2017). One of the biggest threats faced by these structures in outer space is impact damage by micrometeoroid orbital debris (MMOD) traveling at velocities as high as 15 km/s (Lemmens, Krag, Rosebrock, & Carnelli, 2013). This work presents fabrication and testing of hybrid nanocomposites with carbon nanotubes (CNT) and coarse graphene nanoplatelets (GNP) as fillers and flexible epoxy matrix, that are proposed to be used for sensing the impact damage by MMOD in space inflatable structures. CNT and GNP were chosen as fillers owing to their excellent electrical properties and piezoresistivity. A new method was developed to cut graphite sheet (composed of GNPs) in laser marker and distribute it in patterns on carbon nanotube sheet (buckypaper) in epoxy matrix. Piezoresitivity tests were carried out and results were compared with percolation-based Monte Carlo simulations from past research. A hypervelocity impact test was designed and executed at the University of Dayton Research Institute, Ohio, to test the response of the sensors to hypervelocity impacts. Aluminum spheres of 3 mm diameter and 4.5 mm diameter were accelerated to 7 km/s and shot at the sensors, and results were recorded during and after the test. A periodic scanning multichannel control circuit was designed to power the sensors. LabVIEW codes were used for data acquisition and recognizing the location of the damage. The results proved that the hybrid CNT-GNP/epoxy nanocomposites can be used to create a damage detection system which would not only detect the impact damage caused by MMOD of 3mm diameter traveling at 7km/s but also discern its location and depth of penetration by the MMOD.

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