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Full-Text Articles in Mechanical Engineering
Characterization And Modeling Methodology Of Polytetrafluoroethylene Based Reactive Materials For The Development Of Parametric Models, Stephen D. Rosencrantz
Characterization And Modeling Methodology Of Polytetrafluoroethylene Based Reactive Materials For The Development Of Parametric Models, Stephen D. Rosencrantz
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Certain materials, when impacting a target at high velocity will chemically react due to the shock wave passing through them, thereby increasing the damage done by the material. In particular, the reactive materials of interest are capable of acting as both structure and explosive, allowing them to achieve an effect similar to a High Explosive Incindiary (HEI), without the complexity and added mass of fuses. There are a large number of materials/material combinations that could be used in reactive munitions. The purpose of this effort is to determine an efficient analytical characterization methodology that can be validated with a minimal …
Manipulation Of Polystyrene Microparticles On A Microchannel Glass, Ravi Mamillapalli, Henry D. Young
Manipulation Of Polystyrene Microparticles On A Microchannel Glass, Ravi Mamillapalli, Henry D. Young
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Bulk quantities of spherical microbeads have various applications in research and industrial fields. Simple techniques are required to be developed in order to manipulate and modify large numbers of these beads simultaneously. In our experiment, a microchannel glass-based microfluidic device is used to actuate large numbers of microbeads in parallel. The microchannel glass used in these experiments contains channels 4.1 μm in diameter. The microbeads are polystyrene beads which are superparamagnetic in nature and 5-6 μm in diameter. An aqueous suspension of microbeads is injected into a 2-chamber fluid cell that contains a separator, microchannel glass. The beads are reversibly …
Multi-Attribute Optimization Based On Conjoint Analysis, Hemanth K. Amarchinta
Multi-Attribute Optimization Based On Conjoint Analysis, Hemanth K. Amarchinta
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Over the last thirty years, there were tremendous advances in multidisciplinary design optimization in reducing computational cost, developing algorithms for efficient sensitivity analysis in reaching an optimum. Most of these efforts assumed a single objective (attribute) function and a multitude of constraints. Very little work has been done in including the designer's preferences as part of the optimization scheme and in addressing the ability to handle multiple attributes simultaneously. This need to develop a systematic method for including designer's preferences is the main focus of this research work. The concept of modeling preferences among multi-attribute alternatives is prevalent in consumer …
Robust Shape Design Techniques For Steady-State Metal Forming Processes, Jalaja Repalle
Robust Shape Design Techniques For Steady-State Metal Forming Processes, Jalaja Repalle
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Metal forming is a process that transforms a simple shape of a workpiece into a predetermined complex shape through the application of compressive/tensile forces exerted by dies. In the design of a forming process, the only factors that are known are the final component shape and the material with which it is to be made. Then the engineer has to design a process to make defect-free product, subject to limitations of shape, material properties, cost, time, and other such factors. The design cycle can be enhanced if performance sensitivity information is available that could be used with any commercially available …
Investigation Into The Behavior Of Bolted Joints, Steven M. Page
Investigation Into The Behavior Of Bolted Joints, Steven M. Page
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Models to capture the physics of jointed structures have been proposed for over 40 years. These models approximate the behavior of the joint under carefully developed operating conditions. When these conditions change, the model has to be changed. Recent developments in numeric codes like finite elements have created interest in incorporating joint models into the design process but joint models need to represent the joined structure over a broader operating range. This work investigates the dynamic response of a structure with a joint. Isolation of a few dominant effects may give way to a model able to capture a broader …
Computational Study Of Ring-Cusp Magnet Configurations That Provide Maximum Electron Confinement, Taiwo A. Ogunjobi
Computational Study Of Ring-Cusp Magnet Configurations That Provide Maximum Electron Confinement, Taiwo A. Ogunjobi
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Enhancing the confinement of primary electrons within the plasma in a discharge chamber of an ion thruster improves plasma ionization and consequently the thruster's performance. This work computationally calculates the location, position, and orientation of the permanent magnets that provide a ring-cusp magnetic field that maximizes electron confinement in an axi-symmetric cylindrical aluminum-wall discharge chamber. Small samarium cobalt magnets are circumferentially arranged in a ring around the front, side, or back wall of the chamber. The generated ring-cusp magnetic field for any specified magnet configuration is calculated using MAXWELL2D, a two dimensional electromagnetic field simulation computer code. For various magnet …
Using In-Situ Error Tracking For Mode Selection In Proper Orthogonal Decomposition Reduced Order Modelling, Michael Richard Maddux
Using In-Situ Error Tracking For Mode Selection In Proper Orthogonal Decomposition Reduced Order Modelling, Michael Richard Maddux
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Proper Orthogonal Decomposition (POD) provides a method of analyzing data and/or creating a Reduced Order Model (ROM). In this thesis, POD is used to create a ROM comprised of basis functions onto which the governing equations of a Computational Fluid Dynamics (CFD) problem are projected via Galerkin's method. The model is of reduced order since the basis functions span a space smaller than the space from which they were created. A full order simulation called the training period is conducted first to obtain data to be used for creating the ROM using POD. The dominant characteristics are extracted from the …
Large Scale Visualization Of Pulsed Vortex Generator Jets, Kenneth Jay Moore Jr.
Large Scale Visualization Of Pulsed Vortex Generator Jets, Kenneth Jay Moore Jr.
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The use of small jets of air has proven to be an effective means of flow control on low Reynolds number turbine blades. Pulsing of these jets has also shown benefits in reducing the amount of air needed to achieve the same level of flow control. An experiment using Hot Wire Anemometry and Particle Image Velocimetry (PIV) has been used to investigate how these pulsed jets interact with the boundary layer to help keep the flow attached. A 25x scaled jet in a flat plate has been utilized. The 25.4 mm diameter jet has a pitch angle of 30° and …
Innovative Forced Response Analysis Method Applied To A Transonic Compressor, Timothy M. Hutton
Innovative Forced Response Analysis Method Applied To A Transonic Compressor, Timothy M. Hutton
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A set of inlet guide vane (IGV) unsteady surface pressure measurements of a transonic compressor is presented. Using a flexible pressure sensor array, unsteady IGV suction-surface and pressure-surface pressures are acquired for six spanwise by five chordwise locations for various speed lines and throttle settings. Measurements from this sensor array are used to investigate unsteady vane/blade interaction aeromechanical forcing functions in a modern, highly loaded compressor stage. A significant effect is shown on the unsteady forced response of the IGV with changes in compressor operating point and IGV/rotor axial spacing for various span and chord locations. In particular, variations in …
Plastic Dissipation Energy In Mixed-Mode Fatigue Crack Growth On Ductile Bimaterial Interfaces, Jeremy S. Daily
Plastic Dissipation Energy In Mixed-Mode Fatigue Crack Growth On Ductile Bimaterial Interfaces, Jeremy S. Daily
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A new theory of fatigue crack growth in ductile solids has recently been proposed based on the total plastic energy dissipation per cycle ahead of the crack. This and previous energy-based approaches in the literature suggest that the total plastic dissipation per cycle can be closely correlated with fatigue crack growth rates under Mode I loading. The goal of the current study is to extend the dissipated energy approach to steady-state crack growth under mixed-mode loading conditions, with application to cyclic delamination of ductile interfaces in layered materials. The total plastic dissipation per cycle is obtained by 2-D elastic-plastic finite …