Mechanical Engineering Commons^™

Shape-Stabilization Of Pcm/Hdpe Composites With 3d-Printing Applications For Battery Thermal Management, Thomas Benjamin Freeman

Doctoral Dissertations and Master's Theses

Phase-change materials (PCMs) are a useful alternative to more traditional methods of thermal management of Li-ion batteries in electric or hybrid-electric vehicles. PCMs are materials which absorb large amounts of latent heat and undergo solid-to-liquid phase change at near-constant temperature. The goal of this thesis is to experimentally investigate the thermal properties of a novel shape-stabilized PCM/HDPE composite extruded filament. The extruded filament can then be used in a 3D printer for custom PCM/HDPE shapes. These custom PCM/HDPE shapes can be used to help reduce weight, energy consumption, and complexity of the thermal management of the ESS. The PCM used …

Improving Seaglider Efficiency: An Analysis Of Wing Shapes, Hull Morphologies, And Propulsion Methods, Christopher James Hockley

Doctoral Dissertations and Master's Theses

Autonomous underwater gliders are a family of autonomous underwater vehicles used for long-term observation of oceanic environments. These gliders leverage changes in buoyancy and the resulting vertical motion, to generate forward locomotion via hydrodynamic surfaces. In order to function for extended periods, these systems operate in a low-speed, low-drag regime. This research examines factors impacting the operational efficiencies of gliders, including morphological changes, configuration changes, and propulsion. An interesting question arises when considering the operational efficiencies of conventionally propelled systems at the operating speeds typical of gliders. Can a conventional propulsion system match the efficiency of an underwater glider buoyancy …

Sensitivity Analyses Of Optimized Attitude Estimators Using Sensor Fusion Solutions For Low-Cost Mems Configurations, Ryan W. Hoffman

Doctoral Dissertations and Master's Theses

Since the 1990’s, there has been increased focus on creating navigation systems for small unmanned systems, particularly small unmanned aerial systems (SUAS). Due to size, weight, and cost restrictions, compared to larger more costly manned systems, navigation systems for SUAS have evolved to be quite different from the proven systems of the past. Today, there are many solutions for the problem of navigation for SUAS. The problem has now become choosing the most fitting navigation solution for a given application/mission. This is particularly true for evaluating solutions that are fundamentally different.

This research analyses the performance and sensitivity of four …

An Underwater Vehicle Navigation System Using Acoustic And Inertial Sensors, Khalid M. Alzahrani

Doctoral Dissertations and Master's Theses

Unmanned Underwater Vehicles (UUVs) have become an essential tool for different underwater tasks. Compared with other unmanned systems, the navigation and localization for UUVs are particularly challenging due to the unavailability of Global Positioning System (GPS) signals underwater and the complexity of the unstable environment. Alternative methods such as acoustic positioning systems, Inertial Navigation Systems (INS), and the geophysical navigation approach are used for UUV navigation. Acoustic positioning systems utilize the characteristics of acoustic signals that have a lower absorption rate and a more extended propagation distance than electromagnetic signals underwater. The significant disadvantage of the INS is the “drift,” …

Thermal Removal Of Carbon Dioxide From The Atmosphere: Energy Requirements And Scaling Issues, Ted Von Hippel

Publications

I conduct a systems-level study of direct air capture of CO2 using techniques from thermal physics. This system relies on a combination of an efficient heat exchanger, radiative cooling, and refrigeration, all at industrial scale and operated in environments at low ambient temperatures. While technological developments will be required for such a system to operate efficiently, those developments rest on a long history of refrigeration expertise and technology, and they can be developed and tested at modest scale. I estimate that the energy required to remove CO2 via this approach is comparable to direct air capture by other techniques. The …

Multi-Scale Fluid Flow Analysis Of The Cardiovascular System, Zaid Mahmood

Doctoral Dissertations and Master's Theses

The hypoplastic left heart syndrome (HLHS) is one of the rarest congenital heart diseases affecting infants. Out of 150 babies born, one baby suffers from congenital heart disease. Furthermore, nine percent out of those suffering from congenital heart disease specifically suffer from hypoplastic left heart syndrome (HLHS). To this end, the Fontan operation which is a procedure to generate a harmonic blood flow in single functioning ventricle patients has been executed to palliate HLHS patients. In this operation, the inferior vena cava (IVC) and the superior vena cava (SVC), carrying the low-oxygenated blood returning from the lower and upper body …

Experimental Investigation Of A New Spiral Wingtip, Naseeb Ahmed Siddiqui, Mohammed Aldheeb, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

Experiments on the relative merits and demerits of slotted wingtips mimicking a bird’s primary feathers have been performed. The real emargination length of feather tips, their flexibility and curved shapes during cruise are considered in the present study. The experiments were performed at a Reynolds number of 3.7 x 10⁵ on a symmetric flat plate half wing of aspect ratio 3. Lift, drag and pitching moments were measured using a six component aerodynamic balance. Four different shapes inspired by bird primary feathers have been analysed. The rigid curved tip performed the best increasing the L/D ratio by 20%. This …

Manufacturing Process Simulation – On Its Way To Industrial Application, Dennis Otten, Tobias A. Weber, Jan-Christoph Arent

International Journal of Aviation, Aeronautics, and Aerospace

Manufacturing process simulation (MPS) has become more and more important for aviation and the automobile industry. A highly competitive market requires the use of high performance metals and composite materials in combination with reduced manufacturing cost and time as well as a minimization of the time to market for a new product. However, the use of such materials is expensive and requires sophisticated manufacturing processes. An experience based process and tooling design followed by a lengthy trial-and-error optimization is just not contemporary anymore. Instead, a tooling design process aided by simulation is used more often. This paper provides an overview …

Propeller Design Requirements For Quadcopters Utilizing Variable Pitch Propellers, Ian R. Mcandrew, Elena Navarro, Ken Witcher

Publications

Unmanned aerial vehicles, UAV, has increases in the drastically in these past several years since their costs reduced. This research is based and built upon previous research presented in a conference. With the advent of commercial Quadcopters, four propeller systems, are used, being designed and used to operate the advantages of both flight and hovering. The basic design of their propeller blades has not evolved from the early days of manned flight when wooden fixed blades were used. In this paper that expands upon previous findings and discussions it explores the historical developments. Furthermore, how the expansion and reduction in …

Mechanical And Electrical Characterization Of Carbon Fiber/Bucky Paper/Zinc Oxide Hybrid Composites, Suma Ayyagari, Marwan Al-Haik, Virginie Rollin

Publications

The quest for multifunctional carbon fiber reinforced composites (CFRPs) expedited the use of several nano reinforcements such as zinc oxide nanorods (ZnO) and carbon nanotubes (CNTs). Zinc oxide is a semi-conductor with good piezoelectric and pyroelectric properties. These properties could be transmitted to CFRPs when a nanophase of ZnO is embedded within CFRPs. In lieu of ZnO nanorods, Bucky paper comprising mat of CNTs could be sandwiched in-between composite laminae to construct a functionally graded composite with enhanced electrical conductivities. In this study, different configurations of hybrid composites based on carbon fibers with different combinations of ZnO nanorods and Bucky …

Damage Characterization Of Aircraft Fuselage Using Vibrothermography Technique-Review And Analysis, Abbasali Saboktakin

International Journal of Aviation, Aeronautics, and Aerospace

Vibrothermogrphy is a promising non-destructive technique that uses ultrasonic elastic waves to detect damages and is typically applied in the aerospace and automotive industries. This technique allows for defect selective imaging using thermal waves that are generated by ultrasound waves. In this paper, vibrothermography technique was applied to the aircraft fuselage to detect its damage. The influence of the damage on the temperature distribution at the damage region on the aluminum was investigated by finite element technique. Comprehensive understanding in edge crack in fuselage heating caused by local friction between crack surfaces was obtained.