Characterization of Mechanical Properties of Gamma Irradiated Additively Manufactured Articles for In-Space Manufacturing

Recently, additive manufacturing (AM) has opened many doors to engineers across various industries, such as medical, bio-engineering, automotive and recently, aerospace. In an effort to contribute to the development of AM in aerospace industry, a series of experiments were designed to help understand the behavior of 3D printed parts and extend its capabilities and possible uses. The first chapter of this project will focus on understanding the mechanical behavior of additively manufactured articles. In this chapter, a comprehensive effort was undertaken to represent the strength of a 3D printed object as a function of layer thickness by investigating the correlation between the mechanical properties of 3D printed parts and layer thickness. Results showed that samples printed with 0.2 mm layer thickness exhibit higher elastic modulus, ultimate strength and force compared with 0.4 mm. This result has a direct effect on decision making and future use of 3D printing; particularly functional load bearing parts. The second chapter is focused on the effects of gamma irradiation on mechanical properties of hybrid materials as an in-space 3D printing feedstock to investigate the forthcoming possibilities of this technology for future space exploration missions. 3D printed testing samples were irradiated at different dosages from 1 to 1400 kGy using a Cobalt-60 gamma irradiator to simulate space radiation environment. The correlation between the mechanical properties of irradiated samples and accumulated radiation dosage were evaluated by a series of tensile and flexural tests. Findings showed a significant decrease in mechanical performance and noticeable changes in appearance of the parts with accumulated dosage of 1000 kGy and higher. However, for dosages below 10 kGy, samples showed no significant decrease in mechanical performance or change in appearance. These results were used to predict the life of a 3D printed part and demonstrate their potential for use on board the international space station, on low earth orbit satellites, in deep space and long duration missions