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<p>Explosives and rocket fuel are just two prime examples of energetic materials, compounds that contain a combustible fuel and oxidizer within the same substance. Recent advances have enabled the construction of energetic materials through multiple variations of additive manufacturing, principally inkjet, direct-write, fused filament fabrication, electrospray deposition, and stereolithography. Many of the methods used for creating multiple layered objects (three-dimensional) from energetic materials involve the use of highly viscid materials.</p> <p>The focus of this work was to design a process capable of additively manufacturing three-dimensional objects from melt-castable energetic materials, which are known for their low viscosity. An in-depth printer design and fabrication procedure details the process requirements discovered through previous works, and the adaptations available and used to construct an additive manufacturing device capable of printing both energetic and non-energetic (also referred to as inert) melt-castable materials. Initial characterization of three proposed inert materials confirmed their relative similarity in rheological properties to melt-castable energetic materials and were used to test the printer’s performance.</p> <p>Preliminary tests show the constructed device is capable of additively manufacturing melt-castable materials reproducibly in individual layers, with some initial successful prints in three-dimensions, up to three layers. An initial characterization of the printer’s deposition characteristics additionally matches literature predictions. With the ability to print three-dimensional objects from melt-castable materials confirmed, future work will focus on the reproducibility of multi-layered objects and the refined formulation of melt-castable energetic materials.</p>

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Additive friction stir deposition is characterized by rotating a consumable feedstock rod that induces severe plastic deformation to deposit material additively without raising the material past its melting point. In this way, additive friction stir deposition differs from traditional additive manufacturing, and new developments in this technology require further investigation of build parameters, tooling, and resultant builds to better understand this printing process and its applications. This thesis evaluated the effect of rotational speed on aluminum 6061 builds using mechanical testing and microstructural investigations. Three different build conditions were evaluated at 180 RPM, 240 RPM, and 300 RPM. Mechanical testing methods were used to determine hardness values, ultimate tensile strength, yield strength, elastic modulus, and density. Imaging techniques including optical microscopy, electron backscatter diffraction, energy dispersive x-ray spectroscopy, and x-ray computed tomography were used to evaluate microstructure, grain size, chemical composition, and porosity.

With the emergence of modern technologies in manufacturing processes, companies need to adapt themselves to these technologies to stay competitive. Additive Manufacturing is one of the upcoming technologies which will bring major changes to the manufacturing process. AM (Additive Manufacturing) offers flexibility in design, production size, customization, etc., Even though there are numerous advantages from the implementation of AM technologies less than 2% of the manufacturing industries use them for production. The purpose of the thesis was to study the impact of AM on manufacturing industries in 5-10 years and the barriers it is facing for widespread diffusion. Additionally, its impact on Sustainability aspects is also studied. A literature review was conducted to understand the current AM processes, their applications in different manufacturing sectors, their impact on business strategies, operations, and Product Life cycle. From the study, it was concluded that AM technologies are still in their maturing state and has a lot of uncertainties that it must overcome. The most notable barriers being implementation costs, limited materials, and protection of Intellectual property. The thesis also presents the projection for AM in 2030. AM is advantageous for Environmental and Economic sustainability with very little research on Societal sustainability.

Wire and arc additive manufacturing (WAAM) is a manufacturing method using a numerical controlled motion system and a welding system to additively manufacture three dimensional components. The motion system is programmed from three dimensional computer aided design model data (3D-CAD) of the intended geometry which is then sliced in to layers and welded on additively. There are seven process categories within additive manufacturing (AM), each with their own benefits and drawbacks. One of these process categories is directed energy deposition (DED) which uses an energy source to melt material onto a build plate. Instead of filling the build plate with material and selectively melting or sintering the material, DED only deposit material which is to be melted. WAAM is a process within the DED process category. BAE Systems Hägglunds manufactures relatively large components with requirements for mass reduction. Hägglunds has therefor invested in a WAAM laboratory, for testing and investigation on how to utilize this technology to their advantage. During the master thesis a geometrical correlation between the overhang angle and the material deposition on the edges of the overhangs has been found. A slicing strategy utilising this correlation has proven useful in combatting an issue where the top surface of a parallelepiped ends up unwantedly not parallel to the substrate plate. This master thesis has also increased the capability from 30° to 45° overhang angle. A numeric simulation of cooling times in the WAAM process has been developed. The simulation had a maximum error of one minute or about 69 % longer measured than simulated cooling time at worst case.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24849号 / 工博第5166号 / 新制||工||1987(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 泉井, 一浩, 教授 松原, 厚, 教授 平山, 朋子 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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