Document Type

Thesis - Open Access

Award Date

2018

Degree Name

Master of Science (MS)

Department / School

Mechanical Engineering

First Advisor

Todd Letcher

Keywords

3D Printing, Additive Manufacturing, Materials, Thermoplastic

Abstract

3D printing, also called Additive Manufacturing, has increasingly become a focus for research because of the potential to replace complicated assemblies or complex parts with a single printed item. The space industry is very interesting in studying 3d printing with parts being tested and used on rockets, a 3D printer being installed at the International Space Station and is being developed for use in manned exploration of extraplanetary bodies to build habitats. To encourage teams from around the world to develop technologies and materials for autonomous habitat construction using minimal Earth exports, NASA created the 3D Printed Habitat Challenge. NASA is looking for creative and innovative materials and ideas from around the world to aid in reaching their own mission and research goals. To compete in the 3D Printed Habitat Challenge, a thermoplastic concrete was developed that can be 3D printed and used in the future exploration of the solar system. Using HDPE as a binder, the plastic was combined in various weight ratios with sand aggregates to find flexural and compressive strengths. Samples were created by molding mixtures, and later 3D printing with the optimum mixture. The optimum molded mixture was determined to be a 30%wt. HDPE, 70% wt. fine sand aggregate mix, which yielded a flexural yield stress of 14.03 ± 1.59 MPa, and a compressive yield stress of 15.27 ± 0.86 MPa. This mixture was then printed on the large 3D printer and saw increases in flexural and compressive yield strengths to 16.55 ± 0.32 MPa and 21.61 ± 0.04 MPa, respectively. This increase in strength has largely been attributed to the mixing and heating process that occurs organically via the extrusion process. This implies that mixing and heating in the extruder of a lower plastic content mixture could produce better results, with less plastic material. This is a major benefit when plastics are need for construction and must be exported to other planetary bodies.

Library of Congress Subject Headings

Three-dimensional printing.
Thermoplastics.
Extraterrestrial bases -- Design and construction.
Space stations -- Design and construction.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

86

Publisher

South Dakota State University

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Rights Statement

In Copyright