Aerospace Engineering Commons^™

Developing A 7mmx7mm Qfn Package Using Liquid Crystal Polymer, Mitul H. Naik

Mechanical and Aerospace Engineering Theses - Archive

Quad Flat No-Lead (QFN) packages are one of the most widely used and popular packages in the industry. The QFN packages gained popularity in the last decade because of its excellent electrical/thermal characteristics and lower costs. QFN packages are widely used in automotive, defense, handheld devices where space is a constraint and high current circuits require the package is mounted on thick printed circuit boards. This work makes an attempt to develop an economical 7mm*7mm QFN package using Liquid Crystal Polymer (LCP).The first challenge in this work investigate the different grades of LCP to match the electrical as well as …

Fluid-Crack Interaction In Hydraulic Fracturing, Harshil Vora

Mechanical and Aerospace Engineering Theses - Archive

Hydraulic fracturing has been one of the major improvements in petroleum engineering in the past few decades. Since then this process has been used progressively and over million wells have been fracked using hydraulic fracturing technology. A thorough understanding of the formation of fracture network and its propagation is essential to keep evolving the technology. In the present study, the Linear Elastic Fracture Mechanics (LEFM) approach is applied to the crack propagation to understand the fluid crack interaction in brittle rocks under hydraulic loading. The boundary element method (BEM) is used to carry out the numerical analysis. Additionally, an explicit …

Design And Optimization Of Under Tray For Formula Sae Race Car Using Cfd Analysis, Girish Bangalore Jalappa

Mechanical and Aerospace Engineering Theses - Archive

With the advent of inverted wings to produce down-force in Formula-1 during the 1960's, aerodynamics has played a big role in increasing the vehicle performance. An aerodynamics system consists of front, rear wings and an under-tray. This thesis focuses on design of a new under-tray using CFD analysis for a Formula-SAE car.

Simulation Of Indeterminate Multiple, Simultaneous Impact And Contact For A Flexible Multibody System, Rohit Vijay Katti

Mechanical and Aerospace Engineering Theses - Archive

This work presents a method for understanding the impact behaviour of a flexible body undergoing multiple, simultaneous contacts. A continuous model is used with an event-driven function in MATLAB, which detects the collisions. The flexible body is defined as a system of particles, having inter-particle forces in terms of spring, damper coefficients. Equations of motion for such a Flexible MultiBody system are determined and then solved for different phases.In the method presented, the indeterminate nature of equations of motion encountered, during impact, and contact for flexible body are examined. Constraint forces are determined during the different phases of an impact …

Thermo-Mechanical Design Considerations At The Server And Rack Levels To Achieve Maximum Data Center Energy Efficiency, Richard Mark Eiland

Mechanical and Aerospace Engineering Dissertations - Archive

Continually increasing demand for information technology (IT) applications and services has provided sustained growth and interest in data centers. The large amounts of energy consumed by data center facilities have placed a significant emphasis on the energy efficiency of their overall operation. One area of particular importance is the cooling energy required. Heat generation within a data center starts at the server level, specifically within the microelectronic devices that process digital information. Convective heat transfer is the primary driver for the removal of heat from an individual server. As such, cooling efficiency at the server level will be dictated by …

Nanoscale Toughening Mechanisms Of Ultra High Temperature Novel Hfb2 Based Multiphase Ceramics, Zoher Shabbir Lavangia

Mechanical and Aerospace Engineering Theses - Archive

During return of spacecraft they endure very high temperatures (3000°F), few materials can withstand temperatures this high along with additional loads of the spacecraft. Reinforced carbon-carbon (RCC) material system is used as Thermal Protection System (TPS) which is made of laminated graphite rayon-phenolic epoxy, which need to sustain extreme heat. However, these materials are very prone to premature degradation due to oxidation. Silicon Carbide (SiC) and Hafnium Diboride (HfB2) are candidate materials for TPS but, they inherently lack the required toughness for such applications. This research is carried out in two stages, first is to study the individual properties of …

Minimizing Power Consumption At Module, Server And Rack-Levels Within A Data Center Through Design And Energy-Efficient Operation Of Dynamic Cooling Solutions, John Edwards Fernandes

Mechanical and Aerospace Engineering Dissertations - Archive

Data center energy consumption continues to increase with the proliferation in online services such as social networking, banking, entertainment, cloud computing, etc. Recent estimates show that associated power consumption accounts for around 2% and 1.8% of electricity production in the United States and worldwide respectively. In addition to growth in the industry, power densities continue to rise in IT equipment increasing the criticality of thermal management in data center operation. Cooling systems account for around a third of overall power consumption requiring more energy-efficient solutions across all levels within the facility.Liquid cooling of high power modules using cold plates has …

Formalization Of The Engineering Science Discipline - Knowledge Engineering, Xiao Peng

Mechanical and Aerospace Engineering Dissertations - Archive

Knowledge is the most precious ingredient facilitating aerospace engineering research and product development activities. Currently, the most common knowledge retention methods are paper-based documents, such as reports, books and journals. However, those media have innate weaknesses. For example, four generations of flying wing aircraft (Horten, Northrop XB-35/YB-49, Boeing BWB and many others) were mostly developed in isolation. The subsequent engineers were not aware of the previous developments, because these projects were documented such which prevented the next generation of engineers to benefit from the previous lessons learned. In this manner, inefficient knowledge retention methods have become a primary obstacle for …

Aspects Of Intuitive Control Framework: Stabilize, Optimize, And Identify, Pavan Kumar Nuthi

Mechanical and Aerospace Engineering Dissertations - Archive

The duality of estimation and control problems is a well known fact in control theory literature. Parameter convergence and closed loop stability are usually competing interests for a given control scheme. This motivates identification routines to be performed only in offline experiments. On the other hand stable controllers do not guarantee parameter convergence to true parameters. Thus there is a need for a higher level abstraction for a control scheme which acts in stages and prioritizes various aspects at different stages. The stage abstraction for controller is inspired by human intuition towards dealing with control and identification simultaneously and hence …

A Numerical Study Of Microfluidic Droplet Motions In Parallel-Plate Electrowetting-On-Dielectric (Ewod) Devices, Yin Guan

Mechanical and Aerospace Engineering Dissertations - Archive

Microscale water droplet motions in parallel-plate electrowetting-on-dielectric (EWOD) devices including transport, splitting, merging and dispensing have been numerically studied. The transient governing equations for the microfluidic flow are solved by a finite volume scheme with a two-step projection method on a fixed computational domain. The interface between liquid and gas is tracked by a coupled level set and volume-of-fluid (CLSVOF) method. A continuum surface force (CSF) model is employed to model the surface tension at the interface. Contact angle hysteresis which is an essential component in EWOD modeling is implemented together with a simplified model for the viscous stresses exerted …

Improving Fracture Toughness Of Silicon Carbide Based Ceramics By Microstructure Tailoring, Sheikh Fahad Ferdous

Mechanical and Aerospace Engineering Dissertations - Archive

Ceramic materials are one of the most promising materials for wide variety of technical applications such as automotive, aerospace, medical, and other applications. They have very high strengths and high melting points relative to metals. However, low fracture toughness is one of the main barriers of ceramics prohibiting their wide-spread applications. This is because ceramics are mainly bonded with directional bonds which don’t allow dislocations based deformation. Several attempts have been made to increase the toughness of ceramic materials without sacrificing significantly the other mechanical properties. Here three different types of SiC based ceramics have been computationally (atomistic and up-scaled …

Novel Device And Methods For Composite Material Characterization, Michael M. Tadros

Mechanical and Aerospace Engineering Dissertations - Archive

Composite materials have several advantages over metallic materials, with their high specific strength and ability to be elastically tailored to create advantageous structural responses. However, the widespread implementation of composite materials in primary structures is limited by our knowledge of how damage mechanisms interact and spread inside composite parts. To date, characterization has been conducted using one of two methods, surface measurements and subsurface measurements. Surface measurements cannot in general capture the failure of multidirectional composite laminates. Subsurface measurements allow for observations of the internal material structure and damage mechanisms inside the composite which might facilitate greater understanding of the …

Computational Analysis Of I.T. Rack Under Vibration Load, Framroz Meheryar Bharucha

Mechanical and Aerospace Engineering Theses - Archive

Structural failure of a rack due to vibration could result in injury to people, damage to IT equipment, or interruption of services that depend on proper functioning of the IT and networking equipment in the rack. In this topic, a computational study of an IT rack and a group of racks placed adjacent to each other under three vibration load scenarios: transportation, office and earthquake vibration is presented.Each rack can weigh as much as 1600 kg (3500 lb.) when fully populated with IT equipment. Two standards commonly used for testing racks with synthetic seismic loads are the GR-63-CORE Network Equipment …

Performance Analysis Of A Helium Cooled Vhtr Powered Brayton Cycle Topping Unit On An Existing Steam Cycle Using Numerical Propulsion System Simulation, Warren Romao Caetano Freitas

Mechanical and Aerospace Engineering Theses - Archive

With the decommissioning of ageing coal power plants due to outdated technology and high levels of air pollution, the advantages of overhauling existing infrastructure is twofold. First, by providing an alternate, sustainable fuel source, like nuclear power, the problem of air pollution can be brought to check. Second, utilizing existing steam plant infrastructure reduces initial investment costs and allows investors to keep the existing steam plant running until the new infrastructure is ready to go online.The focus of this research is to design and analyze the topping cycle required to support an existing 300 MW power plant based on the …

Quantifying Air Flow Rate Through A Server In An Operational Data Center And Assessing The Impact Of Using Theoretical Fan Curve, Neha Shigrekar

Mechanical and Aerospace Engineering Theses - Archive

Cooling is one of the major cost factors in data centres that accounts for 37% of the total data centre electricity consumption. Demands on cooling systems have increased substantially in recent years, due to increasing server densities. To avoid the overheating of servers, cooling aisles are over provisioned, but little attention is paid to the actual scenario at the server level. Cooling requirements of the servers is calculated on the basis of fan manufacturer’s published data for the air flow capacity of the server fan and system impedance data obtained from the server designer put together. Thus, the air flow …

Performance Characteristics Of Single Effect Lithium Bromide/ Water Absorption Chiller For Small Data Centers, Abhishek Arun Babu Mysore

Mechanical and Aerospace Engineering Theses - Archive

A medium data center consists of servers performing operations such as file sharing, collaboration and email. There are a large number of small and medium data centers across the world which consume more energy and are less efficient when compared to large data center facilities of companies such as GOOGLE, APPLE and FACEBOOK. Such companies are making their data center facilities more environmental friendly by employing renewable energy solutions such as wind and solar to power the data center or in data center cooling. This not only reduces the carbon footprint significantly but also decreases the costs incurred over a …

Chip Package Interaction Study To Analyze The Mechanical Integrity Of A 3-D Tsv Package, Pavan Rajmane

Mechanical and Aerospace Engineering Theses - Archive

The convergence and miniaturization of computing and communications dictates building up rather than out. As planar device miniaturization continues to its ultimate limits, the complexity of circuit interconnections for 2-D devices becomes a limitation for performance and drives up power dissipation [1]. As the consumers demand more functions on their hand-held electronic devices, the need for more devices such as memory, CPU and GPU in hand-held type footprints is increasing. Chip-stacking (3-D) is emerging as a powerful tool that satiates such IC package requirements. A 3-D FPGA would overcome the interconnect limitations, resulting in greater silicon efficiency per function (number …

Experimental Study Of Quaternary Nitrate/Nitrite Molten Salt As Advanced Heat Transfer Fluid And Energy Storage Material In Concentrated Solar Power Plant, Sumeet Changla

Mechanical and Aerospace Engineering Theses - Archive

Solar energy is used to produce electricity by two methods namely photovoltaic and concentrated solar power plant systems. Concentrated Solar power plants hold a distinct advantage over photovoltaic, which is that of energy storage. Energy can be stored in thermal energy storage system during day time and can be used to dispatch energy during peak demand and during raining or cloudy days to produce electricity. All concentrated solar power plants in operation use sensible heat storage method to store energy. Sensible heat storage system have been used in industry owing to ease of dispatch ability. Currently a binary mixture of …

Impact Of Viscoelastic Material Characterization Of Pcb's On Thermomechanical Properties Of Qfn Thick Package Under Thermal Cycling, Karthik Rajashekar

Mechanical and Aerospace Engineering Theses - Archive

The QFN component package is a quad flat pack (QFP) with “no-leads”, where the electrical contact to the printed circuit board (PCB) is made through soldering of the lands underneath the package body rather than the traditional leads formed along the perimeter. The popularity of this device package style is primarily due to the superior electrical and thermal performance demonstrated. It is one of the most cutting-edge technologies emerged in the market, exhibiting high performance with unparalleled cost effectiveness. But using thick PCBs (>3mm) is detrimental to the package reliability. The motivation of this work is to understand and …

Liquid Cooling Of A High-Power Multi-Chip Module Using A Sectioned Cold Plate, Ananthavijayan Sridhar

Mechanical and Aerospace Engineering Theses - Archive

With the advancement in micro-fabrication techniques and high performance chips, the heat flux generated through these electronics is reaching a point where air-cooling of these devices is not efficient enough. By definition, Multi-Chip Modules (MCMs) are specialized electronic packages where multiple Integrated-Circuits (ICs) and semiconductor dies are unified onto a single substrate. Increasing advancements in ICs enable MCMs as alternate packaging finding its application in high power electronics like power generation and cooling, medical devices, lasers and, military electronics etc. Hence, liquid cooling techniques are explored as possible solutions. In this study, a high power MCM is considered and, its …

Evaporative Vapor Deposition For Depositing 2d Materials, Kevin Gleason

Electronic Theses and Dissertations

The development of a new deposition technique called evaporative vapor deposition (EVD) is reported, allowing deposition and formation of atomically-thin, large area materials on arbitrary substrates. This work focuses on the highly popular monolayer material – graphene oxide (GO). A droplet of a GO solution is formed on a heated polymer substrate, and maintained at steady-state evaporation (all droplet parameters are held constant over time). The polymer substrate is laser patterned to control the droplet's contact line dynamics and the droplet's contact angle is maintained using a computer controlled syringe pump. A room temperature silicon wafer is translated through the …

Deposition Thickness Modeling And Parameter Identification For Spray Assisted Vacuum Filtration Process In Additive Manufacturing, August Mark

Electronic Theses and Dissertations

To enhance mechanical and/or electrical properties of composite materials used in additive manufacturing, nanoparticles are often time deposited to form nanocomposite layers. To customize the mechanical and/or electrical properties, the thickness of such nanocomposite layers must be precisely controlled. A thickness model of filter cakes created through a spray assisted vacuum filtration is presented in this paper, to enable the development of advanced thickness controllers. The mass transfer dynamics in the spray atomization and vacuum filtration are studied for the mass of solid particles and mass of water in differential areas, and then the thickness of a filter cake is …

Cacti- And Shorebirds-Inspired Transports Of Liquid Drops And Two Related Fog Collectors, Xin Heng

Mechanical and Aerospace Engineering Dissertations - Archive

Motivated by what has been used in cacti and shorebirds to directionally manipulate water drops, we have explored two approaches to guide the movement of liquid drops. Based on these approaches, in addition to separating oil from its mixture with water, we have further developed two fog collectors. The first fog collector has a configuration similar to its counterpart in a cactus. This collector includes a large ZnO wire and an array of small ZnO wires that are branched on the large wire. All these wires have conical shapes, whose diameters gradually increase from the tip to the root of …

Compact Deployable Antenna For Cubesat Units, Sarah Bolton, Dominic Doty, Peter Rivera

Mechanical Engineering

CubeSats are an appealing platform for space exploration due to their low build and launch costs. Due to their small size, communication rates are often severely limited, preventing missions beyond low earth orbit. A low cost, high gain, high frequency antenna is needed to extend the capabilities of CubeSats.

The goal of the project was to design and build an axisymmetric parabolic antenna that could be deployed from a 10cm x 10cm x 15cm (1.5U) volume and operate at Ka band frequencies. The design selected consisted of an expanding perimeter truss supporting a tensioned mesh reflector. The perimeter truss was …

Magnus Effect In Duct Flow, Jesse S. Batko, Cameron W. Clarke, Kenneth W. Smith Jr.

Williams Honors College, Honors Research Projects

The following research paper details the preliminary research carried out by this team. The project was originally conceived to determine if Magnus Lift could be utilized in an unconventional way to assist rockets during takeoff. Several conceptual designs were proposed, but the idea was scrapped when it became apparent that the team would not be able to generate the desired lift without inducing significant amounts of drag and additional weight on a rocket. Instead, the team focused on researching an interesting topic that hasn’t been previously explored: Magnus lift on a cylinder within a duct.

An experimental procedure that could …

Design And Testing Of An Ox/Ch4 Swirl Torch Ignition System, Gabriel Ricardo Trujillo

Open Access Theses & Dissertations

NASA has renewed its interest in oxygen and methane as propellants for propulsion. Some of the reasons that drive this interest are the ease of storage of liquid methane when compared to hydrogen, the handling safety when compared to hypergols, in-situ resource utilization and its relative clean burning process. This project is part of the larger goal of the Center for Space Exploration Technology Research (cSETR) to better understand the aspects of using this propellants to create future hardware that are specifically optimized for their use. This paper discusses the testing of a previous iteration of the swirl torch igniter …

Adaptive Control For Autonomous Navigation Of Mobile Robots Considering Time Delay And Uncertainty, Stephen Kofi Armah

Dissertations

Autonomous control of mobile robots has attracted considerable attention of researchers in the areas of robotics and autonomous systems during the past decades. One of the goals in the field of mobile robotics is development of platforms that robustly operate in given, partially unknown, or unpredictable environments and offer desired services to humans. Autonomous mobile robots need to be equipped with effective, robust and/or adaptive, navigation control systems. In spite of enormous reported work on autonomous navigation control systems for mobile robots, achieving the goal above is still an open problem. Robustness and reliability of the controlled system can always …

Topology Optimization For Thin Walled Structures Utilizing Simp Method By Additive Manufacturing Using Optimized Conditions, Sajith Anantharaman

Mechanical and Aerospace Engineering Theses - Archive

The objective of this research is to manufacture topology optimized structure by additive manufacturing. Topology Optimization is a method of structural optimization which gives the optimum material distribution in a design domain. This material distribution is then manufactured by additive manufacturing. Additive manufacturing can manufacture complex shapes quite easily since it works by layer-by-layer. This is an on-going field of research and not many optimization algorithms make use of the advantages of additive manufacturing. Numerous researches are done in the field of optimization which are directed towards Homogenization and Solid Isotropic material with Penalization (SIMP). But most of the methods …

Autoignition Behavior Of Synthetic Alternative Jet Fuels: An Examination Of Chemical Composition Effects On Ignition Delays At Low To Intermediate Temperatures, Daniel Valco, Gerald Gentz, Casey Allen, Meredith Colket, Tim Edwards, Sandeep Gowdagiri, Matthew A. Oehlschlaeger, Elisa Toulson, Tonghun Lee

United States Air Force: Publications

The autoignition characteristics of military aviation fuels (JP-5 and JP-8), proposed camelina-derived hydroprocessed renewable jet fuel replacements (HRJ-8 and HRJ-5), Fischer–Tropsch fuels (Shell and Sasol), three Sasol isoparaffinic solvents, as well as 50/50 volumetric blends of the alternative fuels with the conventional fuels are examined. Experiments were conducted in a rapid compression machine and shock tube at compressed temperatures of 625 K ≤ Tc ≤ 1000 K, a compressed pressure of 20 bar, and under stoichiometric and lean conditions. Several implicit properties of the alternative fuels prompted a study of the influence of chemical composition on autoignition, including the influence …

Performance Oriented Adaptive Architectures With Guaranteed Bounds, Benjamin Gruenwald, Tansel Yucelen, Mario Fravolini

Mechanical and Aerospace Engineering Faculty Research & Creative Works

While adaptive control has been used in numerous applications to achieve given system stabilization or command following criteria, the ability to obtain a predictable transient performance is a challenging problem when there is no a priori knowledge about system uncertainties (e.g., their upper bounds and/or domains). In order to address this problem, a new method is presented in [1, 2] utilizing artificial basis functions in the update law of an adaptive control design. This approach is predicated on a gradient minimization procedure and achieves a predictable transient performance without inducing oscillations in the system response as the constant gain due …