Mechanical Engineering Commons^™

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook

Electronic Theses and Dissertations

This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared …

Finite Element Simulation Of Pzt-Aided Interrogation Of Composite Laminates Exhibiting Damage, Amany Micheal, Yehia Bahei-El-Din

Centre for Advanced Materials

Piezoelectricity has proved effective in capturing changes in structures caused by various damage mechanisms. In one approach, piezoelectric wafer active sensors (PWAS) are mounted on the surface of the host structure and utilized as both actuators and sensors to interrogate the structure and monitor its health. This is achieved by subjecting the PWAS to a transient electric pulse and reading the resulting voltage. Changes in the stiffness of the substrate due to structural damage affect the response of the PWAS, which could be correlated to integrity of the structure. Applying this technique to fibrous composite laminates encounters particular challenges due …

Eulerian Cfd Modeling Of Multiphase Internal Injector Flow And External Sprays, Eli T. Baldwin

Doctoral Dissertations

The improvement of combustion systems which use sprays to atomize liquid fuel requires an understanding of that atomization process. Although the secondary break up mechanisms for the far-field of an atomizing spray have been thoroughly studied and well understood for some time, understanding the internal nozzle flow and primary atomization on which the far-field spray depends has proven to be more of a challenge. Flow through fuel injector nozzles can be highly complex and heavily influenced by factors such as turbulence, needle motion, nozzle imperfections, nozzle asymmetry, and phase change. All of this occurs within metallic injectors, making experimental characterization …

Mhd Modeling Of A Copper Slag Cleaning Process, Hongkun Yang, Jörg Wolters, Helmut Soltner, Phillip Pischke, Sven Eckert, Jochen Fröhlich

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Simulation Of The Influence Of Preheating On Stress Distribution During Multi-Pass Repair Welding Of Cast Steel, Wen Wang, Jian-Xin Zhou, Ya-Jun Yin

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Modelling Of Coal-Biomass Blends Gasification And Power Plant Revamp Alternatives In Egypt’S Natural Gas Sector, Dalia A. Ali Eng, Mamdouh A. Gadalla Prof., Omar Y. Abdelaziz, Fatma H. Ashour Prof.

Chemical Engineering

Recently, there has been a growing research interest in the co-gasification of biomass with coal to produce syngas and electricity in a sustainable manner. Co-gasification technology do not only decrease potentially the exploitation of a significant amount of conventional coal resources, and thus lower greenhouse gases (GHG) emissions, but also boost the overall gasification process efficiency. In the present work, a rigorous simulation model of an entrained flow gasifier is developed using the Aspen Plus® software environment. The proposed simulation model is tested for an American coal and the model validation is performed in good agreement with practical data. The …

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing increased vibration …

Improving Ventricular Catheter Design Through Computational Fluid Dynamics, Sofy Hefets Weisenberg

Masters Theses

Cerebrospinal fluid (CSF) shunts are fully implantable medical devices that are used to treat patients suffering from conditions characterized by elevated intracranial pressure, such as hydrocephalus. In cases of shunt failure or malfunction, patients are often required to endure one or more revision surgeries to replace all or part of the shunt. One of the primary causes of CSF shunt failure is obstruction of the ventricular catheter, a component of the shunt system implanted directly into the brain's ventricular system. This work aims to improve the design of ventricular catheters in order to reduce the incidence of catheter obstruction and …

Optical Analysis And Fabrication Of Micro And Nanoscale Plasmonically Enhanced Devices, Avery M. Hill

Physics Undergraduate Honors Theses

Plasmonic nanostructures have been shown to act as optical antennas that enhance optical devices due to their ability to focus light below the diffraction limit of light and enhance the intensity of the incident light. This study focuses on computational electromagnetic (CEM) analysis of two devices: 1) GaAs photodetectors with Au interdigital electrodes and 2) Au thin-film microstructures. Experiments showed that the photoresponse of the interdigital photodetectors depend greatly on the electrode gap and the polarization of the incident light. Smaller electrode gap and transverse polarization give rise to a larger photoresponse. It was also shown that the response from …

Droplet Generation At Megahertz Frequencies, John C. Miers

Mechanical Engineering Undergraduate Honors Theses

Droplet formation has been a fascinating subject to scientists for centuries due to its natural beauty and importance to both scientific and industrial applications, such as inkjet printing, reagent deposition, and spray cooling. However, the droplet generation frequency of common drop-on-demand jetting techniques is mostly limited to ~10 kHz. This paper presents an investigation of the possibility of jetting at megahertz frequencies in order to boost the productivity of drop-on-demand material deposition by ~100 times. The focus of this paper is to understand the limitations of generating droplets at a megahertz frequency and to explore possible solutions for overcoming these …

Optical Analysis And Fabrication Of Micro And Nanoscale Plasmonically Enhanced Devices, Avery M. Hill

Mechanical Engineering Undergraduate Honors Theses

Plasmonic nanostructures have been shown to act as optical antennas that enhance optical devices due to their ability to focus light below the diffraction limit of light and enhance the intensity of the incident light. This study focuses on computational electromagnetic (CEM) analysis of two devices: 1) GaAs photodetectors with Au interdigital electrodes and 2) Au thin-film microstructures. Experiments showed that the photoresponse of the interdigital photodetectors depend greatly on the electrode gap and the polarization of the incident light. Smaller electrode gap and transverse polarization give rise to a larger photoresponse. It was also shown that the response from …

Numerical Investigation Of Full Scale Thunderstorm Downbursts: A Parametric Study And Comparison To Meteorological Model, Christopher Oreskovic

Electronic Thesis and Dissertation Repository

A series of Large Eddy Simulations using an atmospheric meteorological cloud model have been used to investigate the important geometric and thermal parameters that influence a thunderstorm downburst outflow, as it pertains specifically to the idealized cooling source model. A separate set of Large Eddy Simulations make use of the same idealized cooling source model, in a realistic atmospheric base state using real field sounding data, in an attempt to make a quantifiable comparison to a downburst from a full cloud simulation. Randomness has been added to the cooling source forcing function to mimic the thermal variation in a real …

A Model For Complex Heat And Mass Transport Involving Porous Media With Related Applications, Furqan A. Khan

Electronic Thesis and Dissertation Repository

Heat and mass transfer involving porous media is prevalent in, for example, air-conditioning, drying, food storage, and chemical processing. Such applications require non-equilibrium heat and mass (or moisture) transfer modeling inside porous media in conjugate fluid/porous/solid framework. Moreover, modeling of turbulence and turbulent heat and mass transfer becomes essential for many applications. A comprehensive literature review shows a scarcity of models having such capabilities. In this respect, the objectives of the present thesis are to: i) develop a formulation that simulates non-equilibrium heat and mass transfer in conjugate fluid/porous/solid framework, ii) demonstrate the capabilities of the developed formulation by simulating …

Modified Numerical-Analytical Analysis On Scpps, Nima Fathi, Seyed Sobhan Aleyasin, Peter Vorobieff

Nima Fathi

Procesy Cieplne I Aparaty (Lab), Wojciech M. Budzianowski

Wojciech Budzianowski

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Método De Programación Para Plc's Basado En El Estándar Iec61131. Caso De Estudio Proceso De Elaboración De Pan, Daniel Sebastián Molina Cortés, Jader Alvarino Garzón

Ingeniería en Automatización

En este trabajo se presenta un método de programación, desarrollado mediante la aplicación de modelos software, basados en el estándar IEC 61131 parte 3 y 5, con la finalidad de mostrar las ventajas de conocer el estándar, tomando como caso de estudio el proceso de elaboración de croissant de la empresa Donut Factory. En primer lugar, se define el método para la implementación del proyecto, corresponde a, el diseño top-down y la implementación bottom-up, partiendo de este método se realiza su respectivo desarrollo, iniciando con una descripción del proceso, elaboración de diagramas para identificar los instrumentos, una descomposición del proceso …

Inżynieria Chemiczna Lab., Wojciech M. Budzianowski

Wojciech Budzianowski

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Solar Photovoltaic System Control Topology Investigation For Power Source Mismatch, Lynette O'Callaghan

Conference papers

An investigation into solar photovoltaic (PV) system control topology selection, when partial shade is anticipated in the solar array, is presented. As available area is maximised in Building Integrated PV (BIPV) systems, shading is an inevitable consequence. The presence of partial shading in a PV array leads to multiple power peaks in the power-voltage curve, due to bypass diode sections being triggered, and an increase in module mismatch losses in the array. A building energy design software, Integrated Environmental Solutions, is used to determine the shadowed area on PV modules throughout the year, incorporating the PV system location and geometrical …

Project Oasis: Optimizing Aquaponic Systems To Improve Sustainability, Siddharth Nigam, Paige Balcom

Honors Theses and Capstones

Started in Fall 2015, Project OASIS (Optimizing Aquaponic Systems to Improve Sustainability) is an interdisciplinary capstone project with the goal of designing a sustainable and affordable small-scale aquaponic system for use in developing nations to tackle the problems of malnutrition and food insecurity. Aquaponics is a symbiotic relationship between fish and vegetables growing together in a recirculating system. The project’s goals were to minimize energy consumption and construction costs while using universally available materials. The computational fluid dynamics (CFD) software OpenFOAM was used to create transient and steady-state models of fish tanks to visualize velocity profiles, streamlines, and particle movement. …

Modeling Time-Dependent Performance Of Submerged Superhydrophobic Or Slippery Surfaces, Ahmed A. Hemeda

Theses and Dissertations

The goal of this study is to quantify the transient performance of microfabricated superhydrophobic surfaces when used in underwater applications. A mathematical framework is developed and used to predict the stability, longevity, and drag reduction benefits of submerged superhydrophobic surfaces with two- or three-dimensional micro-textures. In addition, a novel design is proposed to improve the drag-reduction benefits of lubricant-infused surfaces, by placing a layer of trapped air underneath the lubricant layer. The new design is referred to as lubricant–infused surfaces with trapped air, and it is designed to eliminate the long-lasting longevity problem of submerged superhydrophobic surfaces. The effectiveness of …

In-Field Fuel Use And Load States Of Agricultural Field Machinery, Santosh Pitla, Joe D. Luck, Jared Werner, Nannan Lin, Scott A. Shearer

Biological Systems Engineering: Papers and Publications

The ability to define in-field tractor load states offers the potential to better specify and characterize fuel consumption rate for various field operations. For the same field operation, the tractor experiences diverse load demands and corresponding fuel use rates as it maneuvers through straight passes, turns, suspended operation for adjustments, repair and maintenance, and biomass or other material transfer operations. It is challenging to determine the actual fuel rate and load states of agricultural machinery using force prediction models, and hence, some form of in-field data acquisition capability is required. Controller Area Networks (CAN) available on the current model tractors …