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Articles 1 - 14 of 14
Full-Text Articles in Engineering
Nd-Fe-B Nanoparticles Through Surfactant Assisted Mechanical Milling And Alloy Design, Jordann M. Bornhoft
Nd-Fe-B Nanoparticles Through Surfactant Assisted Mechanical Milling And Alloy Design, Jordann M. Bornhoft
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Surfactant-assisted mechanical milling has been used to produce discrete nanoparticles of both Nd-Fe-B and Sm-Co amenable for bottom-up production of nanostructured or nanocomposite permanent magnets. However, in Nd-Fe-B the comminution of the material proceeds by transgranular fracture, which influences both the morphology of the nanoparticles and the magnetic properties. This paper utilizes alloy design to alter the fracture behavior from transgranular fracture to intergranular fracture. Nd-rich Nd2Fe14B alloys were produced by melt spinning in an overquenched state. The melt spun ribbons were annealed at 700°C and 800°C to ensure complete crystallization and to form different grain …
Experimental Study On The Effect Of Air Flow On Soap Bubble Formation, John M. Davidson
Experimental Study On The Effect Of Air Flow On Soap Bubble Formation, John M. Davidson
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Soap bubbles are a common interfacial fluid dynamics phenomenon having applications such as buoyant hollow spherical fillers and flow visualization of large scale airflows. In contrast to the dynamics of liquid drops in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented, possibly because soap bubbles have gas-liquid-gas interfaces. Having the thin-liquid-film interface seems to alter the characteristics of the bubble/drop creation process. Thus, the main objective of this study is to experimentally examine how airflow develops and interacts with the soap liquid film as the film stretches and finally collapses to pinch-off. …
Near-Infrared Surface-Enhanced Fluorescence Using Silver Nanoparticles In Solution, Michael D. Furtaw
Near-Infrared Surface-Enhanced Fluorescence Using Silver Nanoparticles In Solution, Michael D. Furtaw
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Fluorescence spectroscopy is a widely used detection technology in many research and clinical assays. Further improvement to assay sensitivity may enable earlier diagnosis of disease, novel biomarker discovery, and ultimately, improved outcomes of clinical care along with reduction in costs. Near-infrared, surface-enhanced fluorescence (NIR-SEF) is a promising approach to improve assay sensitivity via simultaneous increase in signal with a reduction in background. This dissertation describes research conducted with the overall goal to determine the extent to which fluorescence in solution may be enhanced by altering specific variables involved in the formation of plasmonactive nanostructures of dye-labeled protein and silver nanoparticles …
Structural & Magnetic Characterization Study Of Hfco7 Alloy With Substitutions Of Si, Ti, Fe, Mn & B, Jacob A. Lewis
Structural & Magnetic Characterization Study Of Hfco7 Alloy With Substitutions Of Si, Ti, Fe, Mn & B, Jacob A. Lewis
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Magnetic materials are a critical component of the modern technological society. The market of high-energy product hard magnets is dominated by the rare-earth element containing neodymium-iron-boron (NdFeB) magnets. As a result of worldwide demand coupled with trade restrictions on rare-earth minerals, new magnet compositions are explored to reduce pressure on the already strained market. The hafnium-cobalt alloy system has shown promise as a candidate for filling the gap in saturation magnetization between rare-earth containing alloys and those made with abundant elements. This study explores the magnetic effects of silicon, titanium, iron, manganese and boron substitutions in the hafnium-cobalt-7 (1:7 atomic …
Flow-Induced Crystallization Of Isotactic Polypropylene And Random Polyethylene-Polypropylene Copolymers, Frederic Aubin
Flow-Induced Crystallization Of Isotactic Polypropylene And Random Polyethylene-Polypropylene Copolymers, Frederic Aubin
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Flow-induced crystallization (FIC) has been investigated for decades but the effect of molecular characteristics that hinder crystallization—such as the presence of random comonomers— on FIC remains scarcely explored. Flow greatly enhances crystallization kinetics and can induce the formation of highly oriented morphologies that affect final properties (i.e. stiffness, permeability, thermal conductivity, elastic modulus, etc.). Therefore, understanding FIC remains particularly important for developing predictive models to allow optimization of processing techniques involving flows.
Polypropylene represents ~ 40% of the global polyolefin production. The addition of ethylene comonomer allows their use as engineering plastics because of their particular toughness and flexibility. This …
The Mechanics Of Intracranial Loading During Blast And Blunt Impacts – Experimental And Numerical Studies, Veera Selvan Kuppuswamy
The Mechanics Of Intracranial Loading During Blast And Blunt Impacts – Experimental And Numerical Studies, Veera Selvan Kuppuswamy
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Head injuries in an explosion occur as a result of a sudden pressure changes (e.g. shock-blast) in the atmosphere (primary injury), high velocity impacts of debris (secondary injury) and people being thrown against the solid objects (tertiary injury) in the field. In this thesis, experimental and numerical approaches are used to delineate the intracranial loading mechanics of both primary (blast) and tertiary injuries (blunt).
The blast induced head injuries are simulated using a fluid-filled cylinder. This simplified model represents the head-brain complex and the model is subjected to a blast with the Friedlander waveform type of loading. We measured the …
Relaxation Of Shear-Induced Precursors In Isotactic Polypropylene And Random Propylene-Ethylene Copolymers, Benjamin Schammé
Relaxation Of Shear-Induced Precursors In Isotactic Polypropylene And Random Propylene-Ethylene Copolymers, Benjamin Schammé
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Flow induced crystallization (FIC) has a large impact on kinetics and morphology of semicrystalline polymers, and can therefore drastically change final properties such as dimensional and thermal stability, modulus and strength. Processing of polymers usually involves flow, so it is important to understand the mechanism of FIC. It is known that oriented precursors formed during flow are the key to FIC but they are not yet well understood. In this study, flow induced precursors are investigated by examining their relaxation, and the effect of comonomer is probed.
Using a commercial isotactic polypropylene and random propylene-ethylene copolymers, a fiber pull-out technique …
Measurement And Description Of Dynamics Required For In Vivo Surgical Robotics Via Kinematic Methods, Jacob G. Greenburg
Measurement And Description Of Dynamics Required For In Vivo Surgical Robotics Via Kinematic Methods, Jacob G. Greenburg
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
With the goal of improved recovery times and reduced trauma to the patient there has been a substantial shift in the medical community’s demand for minimally invasive surgical (MIS) techniques. With the standardization of MIS becoming more commonplace in the medical field there are still many improvements that are desired. Traditional, manual methods of these surgeries require multiple incisions on the abdomen for the tools and instruments to be inserted. The more recent demand has been to localize the incisions into what is being referred to as a Laparoendoscopic Single-Site (LESS) surgery. Furthermore, the manual instruments that are commonly used …
Developing And Characterizing A Rapid Prototyping Stereo-Lithography Machine To Produce Interpenetrating Polymer Network Systems, Lena R. Butterfield
Developing And Characterizing A Rapid Prototyping Stereo-Lithography Machine To Produce Interpenetrating Polymer Network Systems, Lena R. Butterfield
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Rapid prototyping and interpenetrating network systems (IPNs) ideas and technologies were studied in order to develop a rapid prototyping machine capable of producing IPNs. This work was done as collaboration between the University of Nebraska-Lincoln and the University of Rouen, France, and is part of a project of controlling material property distribution by means of gradient IPN production within a rapid prototyping machine.
A standard stereo-lithography rapid prototyping (RP) machine was built and then modified for the purpose of producing an IPN system composed of an acrylic component, bisphenol A propoxylate diacrylate (BPA-PDA) and an epoxy component, 3,4 epoxycyclohexyl-methyl 3,4 …
Interface Properties Of Bio-Based Composites Of Polylactic Acid And Bamboo Fibers, Quentin Viel
Interface Properties Of Bio-Based Composites Of Polylactic Acid And Bamboo Fibers, Quentin Viel
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Environmental impact plays an ever-increasing role in the industrial production of materials, and because of its importance, the scientific community is examining a wide variety of new materials that are more environmentally friendly. Bioplastics are characterized by the fact that the usual petrochemical resins (polypropylene, polyethylene etc.) are replaced by bio-sourced resins and the reinforcements (glass fibers, carbon fibers etc.) are replaced by natural fibers (bamboo, flax, cotton, etc.). Polylactic acid (PLA) is a biodegradable polymer that is increasingly used in biomedical applications and in packaging. Additionally, bamboo is a promising source of fibers that could be used as reinforcement. …
Design Of A Compliant Underactuated Robotic Finger With Coordinated Stiffness, Etienne Dessauw
Design Of A Compliant Underactuated Robotic Finger With Coordinated Stiffness, Etienne Dessauw
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
The concept of underactuation has been previously developed in the robotic field for grasping applications. For these anthropomorphic grippers, the minimization of the number of input signals, or in other words underactuation, is the most expected characteristic. This method has become very popular in recent decades. Indeed, by minimizing the number of input signals, it minimizes the complexity of the system’s control and at the same time avoids increased weight and cost. The inconvenience of such a technique is that the design of this type of system remains a difficult task if the behavior of the underactuated set of joints …
Development Of A Controllable Polymer System Using Interpenetrating Networks, Emilie Bobo
Development Of A Controllable Polymer System Using Interpenetrating Networks, Emilie Bobo
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
My research partners and I have studied the possibility of building a material system with controllable properties using two interpenetrating polymer networks (IPNs). This study is part of a project to build a rapid prototyping system that allows for the printing of objects with predefined spatial distribution of properties, with the goal that property distributions are controlled though interactions at the molecular level.
One can change the properties of an IPN by adjusting the ratio of interpenetrating networks present in a given cured mixture. This is similar to how one obtains different shades of the color green by gradually changing …
Zone Of Intrusion For Permanent 9.1-Degree Single Slope Concrete Barriers, Cale J. Stolle
Zone Of Intrusion For Permanent 9.1-Degree Single Slope Concrete Barriers, Cale J. Stolle
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Three WDOT 9.1-degree single-slope concrete barriers, with top heights of 36 in. (914 mm), 42 in. (1,067 mm), and 56 in. (1,422 mm) (Standard 14B32), were analyzed for Zone of Intrusion (ZOI)’ and working width using nonlinear finite element analysis (FEA). Tire-barrier friction, vehicle-barrier friction, barrier stiffness, mesh size, tire deflation, and suspension component failures were all found to have effects on simulation results. The zone of intrusion and working width were evaluated for each barrier under varying tire deflation and suspension failure conditions and determined to have a maximum value of 12.2 in. (310 mm) for the front fender …
Design Of Experimental Methods To Test The Performance Of Pads And Helmets Under Blast Loading Conditions, Kurtis Palu
Design Of Experimental Methods To Test The Performance Of Pads And Helmets Under Blast Loading Conditions, Kurtis Palu
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Improvised explosive devices (IEDs) have become a primary weapon in conflicts against US and allied forces. Improvements in body armor and medicine have increased the survivability of such events. These factors have caused an increase in traumatic brain injury (TBI) and mild traumatic brain injury (mTBI) induced by primary blast waves. Injury mechanisms caused from primary blast waves are not clearly understood or defined. How primary blast waves interact with materials or between narrow gaps found between helmet pads is not known. Two novel test fixtures were developed to provide a basic understanding of these two issues.
The first fixture …