Since the late 20th century, breakthroughs in technology have been occurring expeditiously. Indeed, technological innovations have provided the betterment of many aspects of life and ensured humans’ appropriate forms of evolution and civilization. It is safe to claim that medicine has advanced within the past few decades, especially with the upbringing of technological innovations. The world of medicine would not have experienced its recent breakthroughs and profound discoveries without utilizing the available technology. The improvements observed in medicine and technology resulted in better providing of healthcare. Customizing treatments for each patient is now possible. One method of applying customization is through 3D printing of materials such as artificial prosthetics, tissues, and organs. This literature review analyzes 3D printing by stating definitions, assessing its history, discussing its different applications and closing with evaluating future directions. 3D printing first appeared in the late 20th century, and its primary purpose was to design and manufacture products efficiently and accurately. Traditional production of structures involves subtractive manufacturing (carving, cutting, and other methods of reshaping materials) to achieve desired products, whereas 3D printers implement additive manufacturing (a layer-by-layer approach). This provides less time, greater accuracy, and labor-free fabrication of products. Computerized software is one of the essential parts of 3D printing, and functions include designing, scaling, visualizing, controlling production frequency, and many more. In medical applications, the software may require CT scans, cone beam computed tomography, and intraoral scanners (for dental applications). The 3D printing techniques identified in this review are generally applied in oral and maxillofacial procedures—stereolithography, which constructs a product layer-by-layer through curing liquid resin using a UV laser. Digital light projection is a method similar to stereolithography, with a few differences, such as using a UV light instead of a laser and using a liquid crystal display panel. Fused deposition modeling is a technique that melts plastic filaments and extrudes them through a nozzle to form a structure in a layer-by-layer fashion. Selective laser sintering is also similar to stereolithography, where it uses a laser to form an object layer by layer, but the material is a thin layer of plastic powder instead of liquid resin. The power binder printing technique applies droplets onto powdered materials, adhering and forming layers as designed via computerized software. Lastly, computed axial lithography is similar to digital light projection, except the light is projected from many angles at once instead of one layer at a time. The main objectives of this literature review are to investigate each technique, discuss the advantages and disadvantages, and list the commonly applied areas in medicine for each. Also, this review evaluates the current limitations experienced when using 3D printers and suggestions for overcoming them. Some limitations include, but are not limited to, excessive time allocated for producing specific structures, accurate capturing of surgical sites, use of appropriate materials that form printed structures, cost, and deficiencies of reported data. Lastly, this literature review assesses the future projections. The future holds promising breakthroughs in 3D printing technology, including the fabrication of dental stem cells, operating artificial organs, complex vascular tissues, customized artificial alveolar structures for oral and intracranial procedures, and regeneration of periodontal tissues. These projections may occur by overcoming the most reported limitations. Medicine is digitizing rapidly and will continue adapting to the latest technological inventions. The current efforts to advance 3D printing technology will likely positively impact the advancement of many fields, including healthcare, increase chances of positive postoperative outcomes, and potentially combat many health issues society faces today. Professionals across disciplines must come together to further research and educate curriculums to revolve around the innovative technologies to continuing education courses related to 3-D printing technologies.

The focus of this thesis is on the transition from 2D character design to 3D model design, and how this transition affects the appeal, fluidity, and clarity of the 2D design. The source material for this project was an original screenplay entitled The Birds Work for Bea. Three characters from the material were selected for a process including ideation, research, 2D character and style exploration, 3D sculpting, and 3D printing and finishing. This project serves as a study in all aspects of the character concept development pipeline.

Additive manufacturing (AM), also called 3-dimensional printing (3DP), emerged as a disruptive technology affecting multiple organizations' business models and supply chains and endangering incumbents' financial health, or even rendering them obsolete. The world market for products created by AM has increased more than 25% year over year. Using Christensen's theory of disruptive innovation as a conceptual framework, the purpose of this multiple case study was to explore the successful strategies that 4 individual managers, 1 at each of 4 different light and high-tech manufacturing companies in the Netherlands, used to adopt AM technology into their business models. Participant firms originated from 3 provinces and included a value-added logistics service provider and 3 machine shops serving various industries, including the automotive and medical sectors. Data were collected through semistructured interviews, member checking, and analysis of company documents that provided information about the adoption of 3DP into business models. Using Yin's 5-step data analysis approach, data were compiled, disassembled, reassembled, interpreted, and concluded until 3 major themes emerged: identify business opportunities for AM technology, experiment with AM technology, and embed AM technology. Because of the design freedom the use of AM enables, in combination with its environmental efficiency, the implications for positive social change include possibilities for increasing local employment, improving the environment, and enhancing healthcare for the prosperity of local and global citizens by providing potential solutions that managers could use to deploy AM technology.

abstract: This dissertation aims at developing novel materials and processing routes using alkali activated aluminosilicate binders for porous (lightweight) geopolymer matrices and 3D-printing concrete applications. The major research objectives are executed in different stages. Stage 1 includes developing synthesis routes, microstructural characterization, and performance characterization of a family of economical, multifunctional porous ceramics developed through geopolymerization of an abundant volcanic tuff (aluminosilicate mineral) as the primary source material. Metakaolin, silica fume, alumina powder, and pure silicon powder are also used as additional ingredients when necessary and activated by potassium-based alkaline agents. In Stage 2, a processing route was developed to synthesize lightweight geopolymer matrices from fly ash through carbonate-based activation. Sodium carbonate (Na2CO3) was used in this study to produce controlled pores through the release of CO2 during the low-temperature decomposition of Na2CO3. Stage 3 focuses on 3D printing of binders using geopolymeric binders along with several OPC-based 3D printable binders. In Stage 4, synthesis and characterization of 3D-printable foamed fly ash-based geopolymer matrices for thermal insulation is the focus. A surfactant-based foaming process, multi-step mixing that ensures foam jamming transition and thus a dry foam, and microstructural packing to ensure adequate skeletal density are implemented to develop foamed suspensions amenable to 3D-printing. The last stage of this research develops 3D-printable alkali-activated ground granulated blast furnace slag mixture. Slag is used as the source of aluminosilicate and shows excellent mechanical properties when activated by highly alkaline activator (NaOH + sodium silicate solution). However, alkali activated slag sets and hardens rapidly which is undesirable for 3D printing. Thus, a novel mixing procedure is developed to significantly extend the setting time of slag activated with an alkaline activator to suit 3D printing applications without the use of any retarding admixtures. This dissertation, thus advances the field of sustainable and 3D-printable matrices and opens up a new avenue for faster and economical construction using specialized materials. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2019

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Indiana University-Purdue University Indianapolis (IUPUI) / Acrylonitrile Butadiene Styrene (ABS) is the most widely used thermoplastics in 3D printing for making models, prototypes, patterns, tools and end-use parts. However, there is a lack of systematic understanding of the mechanical properties of 3D printed ABS components, including orientation-dependent tensile strength, creep, and fatigue properties. These mechanical properties are critically needed for design and application of 3D printed components. The main objective of this research is to systematically characterize key mechanical properties of 3D printed ABS components, including tensile, creep, and fatigue properties. Additionally, the eff ects of printing orientation on the mechanical prop- erties are investigated. There are two research approaches employed in the thesis: rst, experimental investigation of the tensile, creep, and fatigue properties of the 3D printed ABS components; second, laminate based finite-element modeling of tensile test to understand the stress distributions in different printing layers. The major conclusions of the thesis work are summarized as follows. The tensile test experiments show that the 0 printing orientation has the highest Young's modulus, 1.81 GPa, and ultimate strength, 224 MPa. The tensile test simulation shows a similar Young's modulus as the experiment in elastic region, indicating the robustness of laminate based finite element model. In the creep test, the 90 printing orientation has the lowest k value of 0.2 in the plastics creep model, suggesting the 90 is the most creep resistant among 0 , 45 , and 90 printing orientations. In the fatigue test, the average cycle number under load of 30 N is 3796 revolutions. The average cycle number decreases to 128 revolutions when the load is below 60N. Using the Paris Law, with the crack size of 0.75 mm long and stress intensity factor is varied from 352 to 700 MN -m^3/2 , the predicted fatigue crack growth rate is 0.0341 mm/cycle.

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.

Indiana University-Purdue University Indianapolis (IUPUI) / Since the conception of three dimensional (3D) printing circa 40 years ago, there has been the proliferation of several additive manufacturing (AM) technologies that enable its use in everyday applications such as aerospace, medicine, military, oil and gas and infrastructure. In order to improve its applicability and growth, 3D printed materials are subjected to the same or even higher levels of scrutiny for its mechanical behavior as its conventionally manufactured counterpart. One of the most important mechanical properties is toughness or the ability of a material to undergo large strain prior to fracture when loaded. The toughness of a material can be correlated to its impact energy or the increase in internal energy due to impact. In this study, the impact properties, including the toughness of 3D printed 15-5 stainless steel were investigated at low temperature (77 K), room temperature (298 K) and high temperature (723 K) using experimental and numerical modeling of the Charpy impact test. In addition, ballistic impact simulations were performed to determine the applicability of 3D printed 15-5 stainless steel in the defense industry. The 15-5 stainless steel specimens were printed (horizontal-build) using the direct metal laser sintering (DMLS) technique, cooled or heated to the specified temperature, then tested in accordance with the ASTM E23-2016b [1] standard. The Johnson-Cook (J-C) phenomenological material model and fracture parameters were used in the numerical modeling. The cross-sectional microstructures of surfaces and impact energies of the Charpy impact test were examined. For the ballistic impact simulations, a 3D printed 15-5 stainless steel typical plate was investigated at the same temperatures as the Charpy impact test. A typical missile using the J-C properties at room temperature (298 K) was assigned an initial velocity of 300 ms-1 for each plate temperature. The fracture surface investigation (microsurface analysis as well as visual inspection) and impact energy values of the Charpy impact test show that the 3D printed 15-5 stainless steel exhibited brittle behavior at low and room temperatures, but transitioned into a more ductile behavior at high temperature. At 77 K, 298 K and 723 K, the experimental Charpy impact test results were 0.00 J/cm2, 6.78±4.07 J/cm2 and 50.84±3.39 J/cm2 respectively; whereas the simulated impact energy were 1.05 J/cm2, 10.46 J/cm2 and 47.07 J/cm2 respectively. Hence, the impact energy for the experimental and numerical simulations were in good agreement; especially at higher temperatures. Consistent with the results from the Charpy impact test, the ballistic impact simulations show an increase in the impact energy, elastic plastic strain and deflection of the plate with an increase in temperature indicating brittle-to-ductile behavior. The high exit velocity at low and room temperature may not make the plate attractive in defense in its current configuration; however, at the high temperature, the exit velocity reduction was significant.

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