Indiana University-Purdue University Indianapolis (IUPUI) / Material jetting (MJ) additive manufacturing (AM) has experienced an increased adoption in several industry areas and as well as research applications. One of MJ’s distinct benefits is the ability to print tunable composites, digital materials (DM) by carefully adjusting the ratio of droplets of heterogeneous base-polymeric inks. However, the lack of material information usable in computer simulations has hampered its acceptance in some end-use applications. For these materials to be used in Finite Element Analysis (FEA) simulations the mechanical properties of the DMs need to be characterized into usable material models. DMs printable with an MJ printer has a wide variety of materials properties, ranging from flexible silicone rubber to rigid Acrylonitrile Butadiene Styrene (ABS). Therefore, to cohesively express the mechanical behavior of the DMs it is necessary to utilize non-linear material models. The objective this research is to conduct physical testing to characterize the mechanical behavior of DMs printable with an MJ. Subsequently, to validate the effectiveness of the material models for multi-DM prints. Utilizing the newly characterized material models two use cases were investigated, with the goal of improving the performance of printed parts through simulation. In this study, an MJ printer was used to fabricate the test specimens as well as the components used in the use case studies. The study was focused on the family of six DMs printable from the mixture of the base polymers Tango Black+ (TB+) and Vero White+ (VW+). To characterize the mechanical properties of the materials a tensile test was conducted utilizing the KS-M6518 standard as a basis. The mechanical properties of the DMs were then fitted into four non-linear models and the results compared. The fitted models were, the Neo Hookean model, a two-parameter, three-parameter, and a five-parameter Mooney Rivlin model. To confidently use the material models for multi-DM prints FEA simulations need to validate the accuracy to which they can predict the deformation of the samples under load. To compare the results of the computer simulations and the physical test, strain maps for both results were analyzed. Four different test specimens were printed and tested. A baseline single material samples were compared to three multi-material samples with different embedded structures. The results confirmed the validity of the material models even when used for multi-DM prints. The recently characterized models are utilized in two use case studies which showcase the potential of DMs. The first use case was focused on printing multi-DM substrates for the use of stretchable electronics. The second use case investigated the benefits of utilizing multiple materials to create 3D conductive traces utilizing a new method, the “swollen-off” method. Both case studies showed the benefits of utilizing DMs as well as the applicability of the material models in predictive simulations.

Indiana University-Purdue University Indianapolis (IUPUI) / Ceramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer. The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated. To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively. Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

This work seeks to characterize the impact of build interruptions to additively manufactured Al-Si-10-Mg produced by the powder bed fusion (PBF) process. Additive manufacturing represents a significant investment in overhead, machine, and material making an interruption to the process a potential waste of money and time. Interruptions in the form of power outages, lack of powdered feedstock, and/or shielding gas will cause the machine to operate in an unintended manner, potentially even stopping the build process. The process of manufacturing will influence the microstructure, which determine the material’s properties and performance. An interrupted PBF process could exhibit unique microstructural features and reduced mechanical properties that distinguish the resulting material from a continuous PBF process. Experiments were performed to simulate a production interruption with varying time periods of interruption and air exposure. The zone of interruption was characterized using optical micrographs, EDS, and hardness measurements to determine any effects of the interruption.

<p> Rising costs and volatility in aviation fuel and increased regulations resulting from climate change  concerns have driven gas turbine engine manufacturers to focus on reducing fuel consumption.  Implementing centrifugal compressors as the last stage in an axial engine architecture allows for  reduced core diameters and higher fuel efficiencies. However, a centrifugal compressor's  performance relies heavily on its stationary diffusion system. Furthermore, the highly unsteady  and turbulent flow field exhibited in the diffusion system often causes CFD models to fall short of  reality. Therefore, rapid validation is required to match the speed at which engineers can simulate  different diffuser designs utilizing CFD. One avenue for this is through the use of additive  manufacturing in centrifugal compressor experimental research. This study focused on implementing a new generation of the Centrifugal Stage for Aerodynamic  Research (CSTAR) at the Purdue Compressor Research Lab that utilizes an entirely additively  manufactured diffusion system. In addition, the new configuration was used to showcase the  benefits of additive manufacturing (AM) in evaluating diffusion components. Two diffusion  systems were manufactured and assessed. The Build 2 diffusion system introduced significant  modifications to the diffusion system compared to the Build 1 design. The modifications included changes to the diffuser vane geometry, endwall divergence, and increased deswirl pinch and vane  geometries. The Build 2 diffusion system showed performance reductions in total and static  pressure rise, flow range, and efficiencies. These results were primarily attributed to the changes  made to the Build 2 diffuser. The end wall divergence resulted in end wall separation that caused  increased losses. The changes to the diffuser vane resulted in increased throat blockage and lower  pressure rise and mass flow rate. In addition to the experimental portion of this study, a computational study was conducted to study  the design changes made to the Build 2 diffusion system. A speedline at 100% corrected rotational  speed was solved, and the results were compared to experimental data. The simulated data matched  the overall stage and diffusion system performance relatively well, but the internal flow fields of  the diffusion components, namely the diffuser, were not well predicted. This was attributed to  16 using the SST turbulence model over BSL EARSM. The BSL EARSM model more accurately  predicted the diffuser flow field to the SST model.  </p>