Synthesis, Characterization, And Direct-Ink-Writing Of Syntactic Foams,
2021
University of Texas at El Paso
Synthesis, Characterization, And Direct-Ink-Writing Of Syntactic Foams, Andrea Irigoyen
Open Access Theses & Dissertations
This project encompasses three different methods to fabricate syntactic foams using a PDMS matrix i.e., hollow spheres inclusion, pore generator leaching by solvent, and emulsion. The foam formation by using polysiloxane hollow spheres is done in a 3-step process. The first step is to create a core of polystyrene following a dispersion polymerization process. The goal for the size of the pore is to monodisperse and have an average diameter of 5-10 ÃÂüm, so the polystyrene core must be as well within that range. After that, the cores are coated with a polysiloxane shell by following a polymerization by condensation …
Mechanical Properties And Microstructure Evolution Of Thermally Treated Laser Powder Bed Fusion Alsi10mg,
2021
University of Texas at El Paso
Mechanical Properties And Microstructure Evolution Of Thermally Treated Laser Powder Bed Fusion Alsi10mg, Jorge Merino-Gomez
Open Access Theses & Dissertations
The optimization of mechanical properties with thermal postprocessing treatments was investigated in this study across a wide variety of variants. The relationship between heat treatments and the impacts on the mechanical properties and microstructure of printed materials is a crucial part of additive manufacturing. As a result, the current paper provides a comprehensive overview of postprocess heat treatments for Laser Powder Bed Fusion fabricated AlSi10Mg alloy, including stress relief anneals at 190 and 285 degrees Celsius for 2 hours, hot isostatic pressing at 515 degrees Celsius for 3 hours, hot isostatic pressing + T6 treatment for 6 hours, and final …
Autonomous Control And Signal Acquisition System,
2021
Murray State University
Autonomous Control And Signal Acquisition System, Rion Krampe
Scholars Week
Dr. Bunget has an autonomous control and signal acquisition system that he wants to be repaired and improved upon. This requires that we identify the current issues with the system and repair them as well as make innovations to the system to meet customer needs. The position control needs to be autonomous, and the acquisition of the oscilloscope signal and the transducer position needs to be synchronous. The user should be able to control the position, speed, and how often the signals are captured. The waveform of the scan should be appended into a spreadsheet. The system code also needs …
Quick - Release End Effector Tool
Interface,
2021
Lincoln , NE
Quick - Release End Effector Tool Interface, Shane Farritor, Thomas Frederick
Department of Mechanical and Materials Engineering: Faculty Publications
The various embodiments herein relate to a coupling apparatus for a medical device having a coupler body, a cavity defined in the coupler body, a rotatable drive component disposed within the cavity and having at least two pin receiving openings, and an actuable locking ring disposed around the cavity.
Fatigue Damage Quantification And Life Estimation With Provision For Microstructure,
2021
Louisiana State University
Fatigue Damage Quantification And Life Estimation With Provision For Microstructure, Arash Pourbagheri Jirandehi
LSU Doctoral Dissertations
This dissertation provides methodologies for the quantification of different forms of fatigue damage by considering the role of microstructure. The laws of thermodynamics in conjunction with Finite Element Method (FEM) are utilized to devise thermodynamically-base frameworks for the estimation of cyclic damage in polycrystalline metals. Accordingly, a microstructure-sensitive platform for fatigue life estimation is introduced. The proposed framework is assessed for 3D printed metallic alloys at room and elevated temperatures. Further, it is used to analyze the fatigue performance difference between additively manufactured Inconel 718 in three print orientations. This research is of fundamental vital interest because it ensures that …
In Situ Characterization Of Tensile Behavior
Of Laser Rapid Solidified Al–Si Heterogeneous
Microstructures,
2021
University of Nebraska - Lincoln
In Situ Characterization Of Tensile Behavior Of Laser Rapid Solidified Al–Si Heterogeneous Microstructures, Bingqiang Wei, Wenqian Wu, Dongyue Xie, Huai-Hsun Lien, Metin Kayitmazbatir, Amit Misra, Jian Wang
Department of Mechanical and Materials Engineering: Faculty Publications
Heterogeneous Al–Si microstructure comprising of sub-micron-scale Al dendrites and nanoscale Al–Si fibrous eutectic was fabricated by processing as-cast Al-20wt.%Si alloy using laser rapid solidification. In situ tension tests explored high tensile strength ( ∼ 600 MPa) and ductility ( ∼ 10%) and high strain hardening rate ( ∼ 7 GPa). Microstructural characterization revealed the plastic co[1]deformation mechanisms between soft Al dendrites and hard nanoscale Al–Si eutectic. The progression of plasticity in nanoscale Al–Si eutectic with increasing applied strain is accommodated by dislocation plasticity in the nano-Al channels and cracking Si nanofibers. The propagation of nano-cracks is suppressed by surrounding Al, …
Digitally Twinned Additive Manufacturing: Detecting Flaws In Laser Powder Bed Fusion By Combining Thermal Simulations With In-Situmeltpool Sensor Data,
2021
University of Nebraska - Lincoln
Digitally Twinned Additive Manufacturing: Detecting Flaws In Laser Powder Bed Fusion By Combining Thermal Simulations With In-Situmeltpool Sensor Data, R Yavari, A Riensche, E Tekerek, L Jacquemetton, H Halliday, M Vandever, A Tenequer, V Perumal, A Kontsos, Z Smoqi, K Cole, P Rao
Department of Mechanical and Materials Engineering: Faculty Publications
The goal of this research is the in-situ detection of flaw formation in metal parts made using the laser powder bed fusion (LPBF) additive manufacturing process. This is an important area of research, because, despite the considerable cost and time savings achieved, precision-driven industries, such as aerospace and biomedical, are reticent in using LPBF to make safety–critical parts due to tendency of the process to create flaws. Another emerging concern in LPBF, and additive manufacturing in general, is related to cyber security – malicious actors may tamper with the process or plant flaws inside a part to compromise its performance. …
Molecular Dynamics Simulations Of Self-Assemblies In Nature And Nanotechnology,
2021
CUNY Graduate Center
Molecular Dynamics Simulations Of Self-Assemblies In Nature And Nanotechnology, Phu Khanh Tang
Dissertations, Theses, and Capstone Projects
Nature usually divides complex systems into smaller building blocks specializing in a few tasks since one entity cannot achieve everything. Therefore, self-assembly is a robust tool exploited by Nature to build hierarchical systems that accomplish unique functions. The cell membrane distinguishes itself as an example of Nature’s self-assembly, defining and protecting the cell. By mimicking Nature’s designs using synthetically designed self-assemblies, researchers with advanced nanotechnological comprehension can manipulate these synthetic self-assemblies to improve many aspects of modern medicine and materials science. Understanding the competing underlying molecular interactions in self-assembly is always of interest to the academic scientific community and industry. …
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact,
2021
Air Force Institute of Technology
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Theses and Dissertations
Several additively manufactured lattice designs and configurations were evaluated under compression loads under various strain rates from quasi-static to highly dynamic. These experiments examined how the mechanical behavior of the lattice changed based on the lattice design properties and the applied strain rates. The modulus of elasticity, yield strength, plateau stress, and toughness were observed to decrease with an increase in strain rate, revealing that the lattice designs exhibit a negative strain rate sensitivity. A new lattice flow stress model was developed to account for the mechanical response of the lattice and was incorporated into a computational model for simulation. …
Contact Angle Measurement Using A Hele-Shaw Cell: A
Proof-Of-Concept Study,
2021
University of Nebraska - Lincoln
Contact Angle Measurement Using A Hele-Shaw Cell: A Proof-Of-Concept Study, Haipeng Zhang, Jacob Gottberg, Sangjin Ryu
Department of Mechanical and Materials Engineering: Faculty Publications
Contact angle is an important property to quantify the wettability of a solid surface with a liquid, which characterizes interactions of the solid-liquid pair. Generally, to measure contact angle, special instruments such as a goniometer are necessary, but they are not readily available in certain research settings. In this study, an alternative method to measure contact angle based on a Hele-Shaw cell, microscopy imaging, and image processing is suggested. In this method, a liquid drop is injected into a transparent Hele-Shaw cell, the meniscus of the drop is captured in the top or bottom view using a brightfield microscope, and …
Contact Angle Measurement Using A Hele-Shaw Cell: A
Proof-Of-Concept Study,
2021
University of Nebraska-Lincoln
Contact Angle Measurement Using A Hele-Shaw Cell: A Proof-Of-Concept Study, Haipeng Zhang, Jacob Gottberg, Sangjin Ryu
Department of Mechanical and Materials Engineering: Faculty Publications
Contact angle is an important property to quantify the wettability of a solid surface with a liquid, which characterizes interactions of the solid-liquid pair. Generally, to measure contact angle, special instruments such as a goniometer are necessary, but they are not readily available in certain research settings. In this study, an alternative method to measure contact angle based on a Hele-Shaw cell, microscopy imaging, and image processing is suggested. In this method, a liquid drop is injected into a transparent Hele-Shaw cell, the meniscus of the drop is captured in the top or bottom view using a brightfield microscope, and …
Novel Photothermal Materials And Thermally Engineered Membranes For Solar Desalination,
2021
Washington University in St. Louis
Novel Photothermal Materials And Thermally Engineered Membranes For Solar Desalination, Sisi Cao
McKelvey School of Engineering Graduate Student Theses & Dissertations
Although 71% of earth surface is covered with water, more than 97% of it is saltwater, and freshwater is limited to only about 2.5%. The freshwater shortage has been exacerbated due to the environmental pollution, increased agriculture needs, socio-economic development, and population growth. Among various desalination technologies, membrane distillation has gained wide attention due to its ability to treat highly saline water utilizing waste heat from industrial processes. However, the implementation of conventional membrane distillation is hindered in the remote regions and disaster-struck communities where the low-grade thermal energy from industrial plants and electricity are not readily available. To address …
Flexible Electronics For Neurological Electronic Skin With Multiple Sensing Modalities,
2021
Washington University in St. Louis
Flexible Electronics For Neurological Electronic Skin With Multiple Sensing Modalities, Haochuan Wan
McKelvey School of Engineering Graduate Student Theses & Dissertations
The evolution of electronic skin (E-skin) technology in the past decade has resulted in a great variety of flexible electronic devices that mimic the physical and chemical sensing properties of skin for applications in advanced robotics, prosthetics, and health monitoring technologies. The further advancement of E-skin technology demands closer imitation of skin receptors' transduction mechanisms, simultaneous detection of multiple information from different sources, and the study of transmission, processing and memory of the signals among the neurons. Motivated by such demands, this thesis focuses on design, fabrication, characterization of novel flexible electronic devices and integration of individual devices to realize …
Nucleation Studies In Barium Silicate Glasses And Soda-Lime Silicate Glass,
2021
Washington University in St. Louis
Nucleation Studies In Barium Silicate Glasses And Soda-Lime Silicate Glass, Xinsheng Xia
McKelvey School of Engineering Graduate Student Theses & Dissertations
Controlling nucleation is key for the manufacture of glasses and glass-ceramics. It has been observed by different researchers in many silicate glasses that at low temperatures the critical work of cluster formation (i.e. the nucleation barrier) slowly rises rather than decreasing with decreasing temperature. However, this experimental observation is in contradiction with nucleation theories. In this dissertation, crystal nucleation was studied in BaO·2SiO2, 5BaO·8SiO2, and Na2O·2CaO·3SiO2 glasses. The main research topics include measurements of the nucleation rate, the structural evolution of the glass, and the low-temperature nucleation behavior. A special focus is given to the low-temperature nucleation anomaly. In total, …
Metal Oxide Nanoparticles Synthesized By Nonthermal Plasma For Electrochemical Applications,
2021
Washington University in St. Louis
Metal Oxide Nanoparticles Synthesized By Nonthermal Plasma For Electrochemical Applications, Qinyi Chen
McKelvey School of Engineering Graduate Student Theses & Dissertations
Metal oxide nanocrystals can be synthesized by colloidal processing and gas-phase processing routes. High-quality nanocrystals produced by colloidal routes typically have surface ligands. Transport of electrons and ions among nanocrystals is hindered by surface ligand, and degrades related electrical performance. Gas-phase processing, for example combustion and thermal plasma, can make free-standing nanocrystals. However, nanocrystals produced by combustion method are heavily agglomerated, which further limits the usage of nanoparticles in electrochemical applications. Nonthermal plasma, as an emerging attractive route, has been initially focused on the synthesis of elemental group IV materials, and extended to include the synthesis of multicomponent materials, such …
Structure-Property Relationship In High Strength- High Ductility Combination Austenitic Stainless Steels,
2021
University of Texas at El Paso
Structure-Property Relationship In High Strength- High Ductility Combination Austenitic Stainless Steels, Chengyang Hu
Open Access Theses & Dissertations
Austenitic stainless steels are widely used in our daily life, but their mechanical strength is low. In order to improve their yield strength via grain refinement, an investigation was carried out involving phase reversion annealing concept comprising of severe cold roll reduction followed by annealing at different temperatures for short durations. During annealing reversion of deformation-induced martensite to austenite occurred by shear mechanism, leading to fine-grained structure and high strength-high ductility combination.Nanoscale deformation studies suggested that the deformation mechanism of nanograined structure was different from the coarse-grained counterpart. Post-mortem electron microscopy of plastic zone surrounding the indent indicated that the …
Magnesiothermic Combustion Synthesis Of Nanocrystalline Silicon And Oxidation Kinetics Of Magnesium Particles,
2021
University of Texas at El Paso
Magnesiothermic Combustion Synthesis Of Nanocrystalline Silicon And Oxidation Kinetics Of Magnesium Particles, Sergio Cordova
Open Access Theses & Dissertations
Magnesium (Mg) is a well-known reduction agent in metallurgy (more specifically, in metallothermy). Recently, magnesiothermic reduction of oxides has been used in self-propagating high-temperature synThesis (SHS) of advanced materials such as ultrahigh-temperature ceramics (UHTC). The magnesiothermic SHS has also been used for the conversion of silica (SiO2) to silicon-based materials for thermoelectric applications. However, since oxidation of Mg releases a lot of heat, the direct use of it as the reduction agent leads to excessively high temperatures and undesirable sintering of the products. We have proposed to use magnesium silicide (Mg2Si) instead of Mg in the SHS of nanostructured silicon. …
Methods , Systems , And Devices
Relating To Surgical End Effectors,
2021
Lincoln , NE
Methods , Systems , And Devices Relating To Surgical End Effectors, Shane M. Farritor, Thomas Frederick, Joe Bartels
Department of Mechanical and Materials Engineering: Faculty Publications
The embodiments disclosed herein relate to various medical device components , including components that can be incorporated into robotic and / or in vivo medical devices, and more specifically including end effectors that can be incorporated into such devices. Certain end effector embodiments include various vessel cautery devices that have rotational movement as well as cautery and cutting functions while maintaining a relatively compact structure. Other end effector embodiments include various end effector devices that have more than one end effector.
Investigation And Statistical Modeling Of The Mechanical Properties Of Additively Manufactured Lattices,
2021
Air Force Institute of Technology
Investigation And Statistical Modeling Of The Mechanical Properties Of Additively Manufactured Lattices, Derek G. Spear, Anthony N. Palazotto
Faculty Publications
This paper describes the background, test methodology, and experimental results associated with the testing and analysis of quasi-static compression testing of additively manufactured open-cell lattice structures. The study aims to examine the effect of lattice topology, cell size, cell density, and surface thickness on the mechanical properties of lattice structures. Three lattice designs were chosen, the Diamond, I-WP, and Primitive Triply Periodic Minimal Surfaces (TPMSs). Uniaxial compression tests were conducted for every combination of the three lattice designs, three cell sizes, three cell densities, and three surface thicknesses. In order to perform an efficient experiment and gain the most information …
Robotic Surgical Devices , Systems ,
And Related Methods,
2021
Lincoln , NE
Robotic Surgical Devices , Systems , And Related Methods, Shane Farritor, Erik Mumm, Philip Chu, Nishant Kumar, Jason Dumpert, Yutaka Tsutano
Department of Mechanical and Materials Engineering: Faculty Publications
The embodiments disclosed herein relate to various medical device components, including components that can be incorporated into robotic and / or in vivo medical devices. Certain embodiments include various modular medical devices for in vivo medical procedures.
