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Three Dimensional Finite Element Simulation Of Polymer Melting And Flow In A Single-Screw Extruder : Optimization Of Screw Channel Geometry, Atakan Altinkaynak

Dissertations, Master's Theses and Master's Reports - Open

Single-screw extrusion is one of the widely used processing methods in plastics industry, which was the third largest manufacturing industry in the United States in 2007 [5]. In order to optimize the single-screw extrusion process, tremendous efforts have been devoted for development of accurate models in the last fifty years, especially for polymer melting in screw extruders. This has led to a good qualitative understanding of the melting process; however, quantitative predictions of melting from various models often have a large error in comparison to the experimental data. Thus, even nowadays, process parameters and the geometry of the extruder channel …

Advanced Mechanics Of Materials With Microstructure, Shreehari Elangovan

Dissertations, Master's Theses and Master's Reports - Open

The study of advanced materials aimed at improving human life has been performed since time immemorial. Such studies have created everlasting and greatly revered monuments and have helped revolutionize transportation by ushering the age of lighter–than–air flying machines. Hence a study of the mechanical behavior of advanced materials can pave way for their use for mankind’s benefit. In this school of thought, the aim of this dissertation is to broadly perform two investigations. First, an efficient modeling approach is established to predict the elastic response of cellular materials with distributions of cell geometries. Cellular materials find important applications in structural …

Computational Study Of Internal And External Condensing Flows And Experimental Synthesis To Investigate Their Attainability And Stability In Ground-Based And Space-Based Environments, Shantanu Kulkarni

Dissertations, Master's Theses and Master's Reports - Open

This doctoral thesis presents the computational work and synthesis with experiments for internal (tube and channel geometries) as well as external (flow of a pure vapor over a horizontal plate) condensing flows. The computational work obtains accurate numerical simulations of the full two dimensional governing equations for steady and unsteady condensing flows in gravity/0g environments.

This doctoral work investigates flow features, flow regimes, attainability issues, stability issues, and responses to boundary fluctuations for condensing flows in different flow situations. This research finds new features of unsteady solutions of condensing flows; reveals interesting differences in gravity and shear driven situations; and …

Static And Dynamic Contact Angle Measurement On Rough Surfaces Using Sessile Drop Profile Analysis With Application To Water Management In Low Temperature Fuel Cells, Vinaykumar Konduru

Dissertations, Master's Theses and Master's Reports - Open

Fuel Cells are a promising alternative energy technology. One of the biggest problems that exists in fuel cell is that of water management. A better understanding of wettability characteristics in the fuel cells is needed to alleviate the problem of water management. Contact angle data on gas diffusion layers (GDL) of the fuel cells can be used to characterize the wettability of GDL in fuel cells. A contact angle measurement program has been developed to measure the contact angle of sessile drops from drop images. Digitization of drop images induces pixel errors in the contact angle measurement process. The resulting …

Vibro-Acoustical Analysis And Design Of A Multiple-Layer Constrained Viscoelastic Damping Structure, Fei Lin

Dissertations, Master's Theses and Master's Reports - Open

The goal of this research is to provide a framework for vibro-acoustical analysis and design of a multiple-layer constrained damping structure. The existing research on damping and viscoelastic damping mechanism is limited to the following four mainstream approaches: modeling techniques of damping treatments/materials; control through the electrical-mechanical effect using the piezoelectric layer; optimization by adjusting the parameters of the structure to meet the design requirements; and identification of the damping material’s properties through the response of the structure. This research proposes a systematic design methodology for the multiple-layer constrained damping beam giving consideration to vibro-acoustics.

A modeling technique to study …

Quantification Of Relativistic Perturbation Forces On Spacecraft Trajectories, Nicholas Palma Mastricola

Dissertations, Master's Theses and Master's Reports - Open

The intent of the work presented in this thesis is to show that relativistic perturbations should be considered in the same manner as well known perturbations currently taken into account in planet-satellite systems. It is also the aim of this research to show that relativistic perturbations are comparable to standard perturbations in speciffc force magnitude and effects. This work would have been regarded as little more then a curiosity to most engineers until recent advancements in space propulsion methods { e.g. the creation of a artiffcial neutron stars, light sails, and continuous propulsion techniques. These cutting-edge technologies have the potential …

Energy Harvesting From Body Motion Using Rotational Micro-Generation, Edwar. Romero-Ramirez

Dissertations, Master's Theses and Master's Reports - Open

Autonomous system applications are typically limited by the power supply operational lifetime when battery replacement is difficult or costly. A trade-off between battery size and battery life is usually calculated to determine the device capability and lifespan. As a result, energy harvesting research has gained importance as society searches for alternative energy sources for power generation. For instance, energy harvesting has been a proven alternative for powering solar-based calculators and self-winding wristwatches. Thus, the use of energy harvesting technology can make it possible to assist or replace batteries for portable, wearable, or surgically-implantable autonomous systems. Applications such as cardiac pacemakers …

Structural And Surface Property Characterization Of Titanium Dioxide Nanotubes For Orthopedic Implants, Tolou Shokuhfar

Dissertations, Master's Theses and Master's Reports - Open

This research focused on the to modification of the surface structure of titanium implants with nanostructured morphology of TiO₂ nanotubes and studied the interaction of nanotubes with osteoblast cells to understand the parameters that affect the cell growth. The electrical, mechanical, and structural properties of TiO₂ nanotubes were characterized to establish a better understanding on the properties of such nanoscale morphological structures.

To achieve the objectives of this research work I transformed the titanium and its alloys, either in bulk sheet form, bulk machined form, or thin film deposited on another substrate into a surface of titania nanotubes …

Parametric Combustion Modeling For Ethanol-Gasoline Fuelled Spark Ignition Engines, Yeliana

Dissertations, Master's Theses and Master's Reports - Open

Ethanol-gasoline fuel blends are increasingly being used in spark ignition (SI) engines due to continued growth in renewable fuels as part of a growing renewable portfolio standard (RPS). This leads to the need for a simple and accurate ethanol-gasoline blends combustion model that is applicable to one-dimensional engine simulation.

A parametric combustion model has been developed, integrated into an engine simulation tool, and validated using SI engine experimental data. The parametric combustion model was built inside a user compound in GT-Power. In this model, selected burn durations were computed using correlations as functions of physically based non-dimensional groups that have …

Modeling Mechanical Response Of Heterogeneous Materials, Siladitya Pal

Dissertations, Master's Theses and Master's Reports - Open

Heterogeneous materials are ubiquitous in nature and as synthetic materials. These materials provide unique combination of desirable mechanical properties emerging from its heterogeneities at different length scales. Future structural and technological applications will require the development of advanced light weight materials with superior strength and toughness. Cost effective design of the advanced high performance synthetic materials by tailoring their microstructure is the challenge facing the materials design community. Prior knowledge of structure-property relationships for these materials is imperative for optimal design. Thus, understanding such relationships for heterogeneous materials is of primary interest. Furthermore, computational burden is becoming critical concern in …

Mathematical Analysis For Perceived Annoyance Of Impulsive Sounds In Terms Of Physical Factors, Gayatri S. Kadlaskar

Dissertations, Master's Theses and Master's Reports - Open

From the customer satisfaction point of view, sound quality of any product has become one of the important factors these days. The primary objective of this research is to determine factors which affect the acceptability of impulse noise. Though the analysis is based on a sample impulse sound file of a Commercial printer, the results can be applied to other similar impulsive noise.

It is assumed that impulsive noise can be tuned to meet the accepTable criteria. Thus it is necessary to find the most significant factors which can be controlled physically. This analysis is based on a single impulse. …