Indiana University-Purdue University Indianapolis (IUPUI) / Bronze is a popular metal for many important uses. Currently, there are no economical 3D printers that can print Bronze powders. A recent product, Bronze Metal Clay (BMC) has arrived. Additionally, commercial metal 3D printers require laser or electron beam sources, which are expensive and not easily accessible. The objective of this research is to develop a new two-step processing technique to produce 3D printed metallic component. The processing step includes room temperature 3D printing followed by high-temperature sintering. Since no material data exists for this clay, the tensile strength and hardness properties of BMC are compared to wrought counterpart. In this research tests are completed to determine the mechanical properties of Cu89Sn11 Bronze Metal Clay. The author of this thesis compares the physical properties of the same material in two different formats: 3D printed clay and molded clay. Using measured stress-strain curves and derived mechanical properties, including Young's modulus, yield strength, and ultimate tensile strength, the two formats demonstrate inherit differences. The Ultimate tensile strength for molded BMC and 3D-printed specimens sintered at 960 C was 161.94 MPa and 157 MPa, respectively. A 3D printed specimen which was red at 843 C had 104.32 MPa tensile strength. Factory acquired C90700 specimen had an ultimate stress of 209.29 MPa. The Young's modulus for molded BMC and 3D-printed specimens sintered at 960 C was 36.41 GPa and 37.05 GPa, respectively. The 843 C 3D-printed specimen had a modulus of 22.12 GPa. C90700 had the highest modulus of 76.81 GPa. The Yield stress values for molded BMC and 3D-printed specimens sintered at 960 C was 77.81 MPa and 72.82 MPa, respectively. The 3D-printed specimen had 46.44 MPa. C90700 specimen had 115.21 MPa. Hand molded specimens had a Rockwell hardness HRB85, while printed samples had a mean of HRB69. Also, molded samples recorded a higher Young's Modulus of 43 GPa vs. 33 GPa for the printed specimens. Both samples were weaker than the wrought Cu88:8Sn11P0:2 which had a 72 GPa. Cu88:8Sn11P0:2 also was a harder material with an HRC45. The property di erence between 3D printed, molded, and wrought samples was explained by examining their micro structures. It shows that 3D printed sample had more pores than the molded one due to printing process. This study demonstrates the flexibility and feasibility of using 3D printing to produce metallic components, without laser or electron beam source.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第17904号 / 農博第2027号 / 新制||農||1018(附属図書館) / 学位論文||H25||N4800(農学部図書室) / 30724 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 杉山 淳司, 教授 矢野 浩之, 教授 髙部 圭司 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19184号 / 工博第4061号 / 新制||工||1626(附属図書館) / 32176 / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 田畑 修, 教授 琵琶 志朗, 准教授 土屋 智由, 教授 松原 厚 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19708号 / 工博第4163号 / 新制||工||1642(附属図書館) / 32744 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 白井 泰治, 教授 乾 晴行 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20361号 / 工博第4298号 / 新制||工||1666(附属図書館) / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 安達 泰治, 教授 小寺 秀俊, 教授 田畑 修 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Student Number : 9800022T - PhD thesis - School of Mechanical, Industrial and Aeronautical Engineering - Faculty of Engineering and the Built Environment / For many applications, it may be useful to be able to estimate creep properties of a material from simpler testing procedures such as tensile tests than the conventional creep testing procedures. Most alloys used for creep service conditions are in a hardened condition and thus tertiary creep, controlled by micro structural degradation, is dominant. The object of the study was to investigate a reasonably simple method for estimating the creep behavior of a low alloy 1% Cr, 0.25 % Mo steel from tensile yield data. The study involved performing of series of investigations, including age hardening, tensile and creep tests. Microstructural degradation was monitored from specimens held in a furnace for different times and temperatures, which were then tested in tension at room temperatures. Tensile tests were carried out at different temperatures and strain rates and the data used to determine material parameters for use in kinetic equations describing deformation. For comparison, creep curves were obtained from both creep tests and tensile tests results. Tests on furnace aged specimens were used to quantify softening due to material degradation and formulate a structure evolution and kinetic expressions used to determine creep curves. The modified equation by Dorn was used to determine the material parameters and to predict flow characteristics. Two sets of mechanisms were observed. At low temperature and high stress (above 550MPa) dislocation by glide mechanism was investigated. At higher temperatures and low stress (below 550MPa), some form of power law creep was observed. Glide mechanism was investigated and material parameters σ ) , n and activation volume v, were calculated. The calculated value of σ ) was assumed for both plastic deformation and the softening kinetics. A reasonably good estimate of the creep behavior of the low alloy steel used in this investigation in which tertiary creep dominates can be calculated from tensile yield stress values. Furthermore, the creep rate and recovery have similar stress dependences, with the stress and temperature dependence similar to that predicted by recovery theory. The value of activation energy observed for creep for this alloy is in line with the processes which could be related to self diffusion. In order to justify the significance of this study, four existing empirical models are discussed, highlighting their merits and demerits with respect to the models used in this study. These are θ-Projection, Damage Mechanics, Estrin-Mecking and the Internal Stress Methods. Generally, in this class of alloys, recovery process occurs under an effective stress (i.e. an applied stress less the internal stress). Thus the possibility of using tensile data obtained in this study in the internals stress model was explored. The model could replicate the one used in this study if the change in internal stress value o σ is assumed to be negligible. This could be assumed to be true for tensile data at high stresses and low temperature especially during secondary creep rate when the internal stress approximates to the applied stress and at short test durations.

Hexagonal close packed (hcp) crystal structures, such as magnesium and titanium, provide formidable strength in relation to density. Current interests in reducing CO2 emissions, hold magnesium as a contender to lightweight passenger vehicles. Although significant decreases in mass could be achieved through magnesium, poor formability and energy absorption capacity limit the possibility for cost-effective production. This Master’s thesis aims to observe the microstructure and micro texture evolution induced by twinning using interrupted electron backscattered diffraction (EBSD) characterization in order to determine potential mechanisms causing early failure of magnesium alloys. This study revealed {10-11} contraction twins at stress levels contrary to the basic hypothesis of the Schmid effect revealing the importance of non-Schmid effects in damage. Furthermore, it was observed that crack nucleation occurs in magnesium alloys, due mainly to interaction between twins and microstructure defects and form inside contraction twins, causing cleavage-like terraces in the fracture surface.

Hereditary Equine Regional Derma Asthenia (HERDA) is a painful disfiguring autosomal recessive skin disorder of Quarter Horse lineages. Affected horses cannot be ridden and most are humanely destroyed. Five years following homozygosity mapping of a putative causal mutation responsible for HERDA, it remains unclear how this mutation causes the HERDA syndrome. HERDA horses have a missense mutation in peptidyl-prolyl cis-trans isomerase B (PPIB) which encodes cyclophilin B (CYPB) and alters folding and post-translational modifications of fibrillar collagen. Loss of function mutations in CYPB recognized in other species classically present as the debilitating bone disease, severe to lethal osteogenesis imperfect (OI). Objectives of this study were to develop a novel method for cryogenic clamping of tendons and ligaments of high tensile strength and validate its performance by ultimate tensile strength testing of normal equine deep digital flexor tendon. This validated method was then used to compare tendon and ligament of HERDA vs. control horses along with great vessels and skin. We hypothesized that all tissues of high fibrillar collagen content would have altered tensile properties due to the CYPB mutation affecting fibrous connective tissue globally within HERDA horses. Based on previous studies in our laboratory identifying reduced hydroxylysine content and altered collagen crosslink ratios in the skin of HERDA affected animals that implicate lysyl hydroxylase-1 (LH1) dysfunction, we hypothesized that the HERDA PPIB mutation modified an interaction between CYPB and LH1, interfering with hydroxylysine synthesis and its availability for collagen crosslink formation. In addition, we hypothesized that mutant CYPB may also lead to modifications of other known CYPB protein complexes, such as the CYPB, prolyl-3 hydroxylase-1 (P3H1) and cartilage associated protein (CRTAP) triplex. Goals of this study were to investigate the tensile properties of tissues with high fibrillar collagen content from HERDA homozygotes, to elucidate the mechanistic relationship of the HERDA CYPB mutation to the clinical disease, and to provide evidence to substantiate a heterozygote phenotype in HERDA which could be useful to explaining the correlation between lineages that carry the HERDA allele and performance outcomes in the discipline of western cutting competition.