Aerospace Engineering Commons^™

Determination Of Guidance Laws For Uav Systems In Communication Networks Using Collision Cone Theory, Utsav Mudgal

Mechanical and Aerospace Engineering Theses - Archive

Unmanned Aerial Vehicles (UAVs), also commonly known as drones, are used in various applications, including military applications such as surveillance and intelligence-gathering as well as civilian applications such as search and rescue. The use of UAVs to form communication networks is a topic of active research interest. This thesis aims to investigate the development of guidance laws for multiple UAVs to form such communication networks. Toward this end, this thesis employs tools from collision cone theory and incorporates them with parameters used to describe a communication network. Different types of networks are evaluated for use of the guidance laws. Simulation …

Guidance Laws For N-Mobile Agents To Grip A Moving Target, Pranay Gadiya

Mechanical and Aerospace Engineering Theses - Archive

In this thesis, we consider the problem of n mobile agents carrying a gripper, with the objective of gripping a moving circular target. The target may move with constant velocity, or even maneuver. We develop guidance laws by which the agents can first cage the target and subsequently grip it. These guidance laws are developed based on a collision cone framework, using which the mobile agents cooperatively steer their velocity vectors in an appropriate fashion to meet their objective. It is assumed that each of the mobile agents are equipped with a lidar sensor, using which they obtain the range …

Buckling Load Optimization Of Variable Stiffness Composite Plate Using Fem And Semi-Analytical Method, Jeegar Vallabhbhai Patel

Mechanical and Aerospace Engineering Theses - Archive

The advent of new composite manufacturing techniques like Automated Fiber Placement (AFP) offers greater flexibility in structural designs by allowing curvilinear fiber paths. Hence, it is now possible to change laminate stiffness locally, thereby enabling Variable Stiffness (VS) composite structures. Such structures demonstrate superior buckling performance over traditional constant stiffness structures. However, obtaining the optimum fiber paths to improve buckling performance remains an open area of research due to the complexity of determining such fiber paths. This research investigated two approaches for optimizing fiber paths; First, a Finite Element Method (FEM) approach that utilizes linear shape functions to interpolate local …

A Modular Platform For Intrusive Diagnostics And Tps Testing In The Onr-Uta Arc-Jet Facility, Blake Anthony Hamilton

Mechanical and Aerospace Engineering Theses - Archive

This work presents an approach to the design, and successful experimental implementation, of a modular platform for intrusive diagnostics and TPS testing in the ONR-UTA Arc-Heated Wind Tunnel "Leste" Facility. The harsh conditions typical of arc-jet facilities (hypersonic, high-enthalpy, chemically-reacting, continuous flows) present a challenge to the design of insertion platforms. In this work a detailed analysis of the aerothermal loads is used to aid in the design process. Specific design points for this modular platform and its ancillary instrumentation have been identified. Based on this design approach, a modular platform for intrusive diagnostics and TPS testing has been developed. …

Investigation Into Wedge Turbulator Effects In High Aspect Ratio Cooling Channels, Daniel Garcia

Electronic Theses and Dissertations, 2020-2023

With reusability being a novel design parameter for liquid rocket engines (LRE), the need to lower internal wall temperatures for an increased engine longevity is a desired outcome. One of the mechanisms that has been effectively implemented is the use of high aspect ratio cooling channels (HARCC) to promote fin-like effects from internal cooling channel sidewalls. In the gas turbine industry, the use of wedge turbulators has gained recognition for its heat augmentation properties with relatively low pressure drop penalty. In an ideal case, LRE's could adopt the wedge turbulator cooling technique to enhance the benefits of HARCC with minimal …

Theoretical Prediction Of Mechanical Behavior Of Regular And Chiral Honeycombs Based On Loading Of Single Cell., Sai Krishna K. Pinnamaneni

Mechanical and Aerospace Engineering Dissertations - Archive

Cellular solids are both naturally occurring and man-made materials depending on the characteristic length or Stochastic manner, these materials exhibit a low-relative density usually 30% than the constituent solid material. Low-density cellular solids have been demonstrating superior mechanical properties in various applications from marine to aerospace and lightweight sandwich structures, which has intrigued in development of novel structured materials. Cellular solids offer great design flexibility ashowows how for the targeted geometric for the application-based industry. These materials are used in sandwich structures and come in the shape of hexagonal. An additional aspect of determining the properties and behavior is by …

Multi-Parametric And Multi-Objective Optimization Of Heatsinks For Forced And Natural Convection Based Single-Phase Immersion Cooling Of Server, Tushar Rohidas Wagh

Mechanical and Aerospace Engineering Theses - Archive

An increase in utility of internet-based services, cloud computing and greater performance demands due to rising AI and ML applications have led to a steep growth in GPU and CPU thermal design power. Efficient thermal management of these processors has become a bottleneck in performance enhancement and corresponding power densification of these components. Furthermore, increased pressure on data center owners to reduce power demands and move towards green computing has exacerbated the data center cooling challenges. Single-phase immersion cooling allows data center owners to not only dissipate the increasing heat fluxes efficiently but can also potentially improve equipment reliability as …

Airframe And Systems Design, Analysis, And Testing Of The Horizon Morphing-Wing Aircraft, Sabrina A. Snow

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Morphing trailing edge technology can provide the ability to dynamically alter the twist distribution, and therefore lift distribution, of an aircraft during flight. There are certain optimal lift distributions which can be chosen to create proverse yawing effects and eliminate the need for vertical control surfaces. The purpose of this project is to support the design and testing of a morphing, crescent flying wing airframe which will be used to evaluate yaw control in an aircraft without vertical control surfaces. There are three main objectives of this project, which are to perform static and dynamic analysis on the crescent wing …

On Mode Transition Phenomenon And Operating Conditions In Rotating Detonation Rocket Engines, Taha Rezzag-Lebza

Electronic Theses and Dissertations, 2020-2023

The work presented herein consist of first studying the instantaneous properties of the detonation waves in a rotating detonation rocket engine by tracking each individual wave and recording its position, velocity, and peak intensity as it travels around the annulus. Results for a steady portion of a test performed on a rotating detonation rocket engine show that the wave properties exhibit oscillatory behavior. Results obtained from the rotating detonation rocket engine show that the properties are highly dependent on the azimuthal position. In an attempt to understanding the cause of such a behavior, similar investigations were performed on an air-breathing …

Developing A Light Curve Simulation Tool For Ground And Space-Based Observations Of Spacecraft And Debris, Andrew T. Ochoa

Master's Theses

A light curve is a plot of brightness versus time of an object. Light curves are dependent on orbit, attitude, surface area, size, and shape of the observed object. Using light curve data, several analysis methods have been developed to derive these parameters. These parameters can be used for tracking orbital debris, monitoring satellite health, and determining the mission of an unknown spacecraft.

This paper discusses the development, verification, and utilization of a tool that simulates light curve data. This tool models ground-based observations, space-based observations, self-shadowing geometry, tumbling debris, and controlled spacecraft. The main output from the tool is …

Tradespace Exploration Of A Uav Conceptual Design Using Model-Based Systems Engineering, Ayan Srivastava

All Theses

The objective of this research is to apply model-based systems engineering approaches to the conceptual design of unmanned aerial vehicles. This is accomplished by evaluating the models of aircraft performance, extracting input and output parameters from the models, creating chains of models, and implementing the models in the MATLAB programming language. By following this process, it is possible to identify the global parameters that remain constant across models, the shared input parameters, the dependencies between models, and the feedback loops with the systems models.

The models are currently implemented in two files using Microsoft MS Excel, one is focused on …

Creep Behavior And Deformation Mechanisms Of Spark Plasma Sintered Oxide Ceramics For Aerospace Systems At 1300˚C - 1400˚C, David D. Swanson

Theses and Dissertations

The mechanical behavior of YAG and LuAG was investigated at elevated temperatures. The specific materials investigated in this work include high-purity, polycrystalline YAG, high-purity, polycrystalline LuAG, and two doped variants of YAG: 2at% Yb-doped, polycrystalline YAG and 2at% Er-doped, polycrystalline YAG. Several billets of each material were prepared and processed by means of spark plasma sintering (SPS). Many different sintering parameters were utilized in order to obtain materials with various physical properties and to identify the effects of sintering parameters on the average grain size of the resulting materials. The compressive creep behavior of these materials was investigated at 1300°C …

Space Domain Awareness Assessment Of Cislunar Periodic Orbits For Lagrange Point Surveillance, Adam P. Wilmer

Theses and Dissertations

Cislunar periodic orbits provide an elegant means to fill the observational capability gaps which are present in ground-based and/or near-Earth spaced-base sensors. This research involves theoretical analysis on the effectiveness of cislunar periodic orbits for Space Domain Awareness (SDA) mission architectures. Specifically, cislunar periodic orbits are analyzed, both individually and in constellations with one another, for their effectiveness at monitoring target satellites in Lyapunov and halo orbits about the Earth - Moon L1 and L2 Lagrange points. All orbits are created and modeled in the Circular Restricted Three-Body Problem (CR3BP), then subject to perturbations in both the Elliptical Restricted Three-Body …

Design, Development, And Testing Of Embedded Computing On Afit's Control & Autonomy Space Proximity Robot (Caspr), Collin A. Gwaltney

Theses and Dissertations

This thesis reviews RPO algorithm testbeds and discusses the development of the Control and Autonomy Space proximity Robot (CASpR) kinematic testbed housed at the Air Force Institute of Technology (AFIT). CASpR operates on a rail system to propagate the trajectories of two satellites using the Hill-Clohessy-Wiltshire (HCW) Equations of Motion (EOMs). In this study, the implementation of a Jetson TX2i as an onboard flight computer is discussed and accomplished. Each hardware component used in the process of adding embedded computing as well as the software and paths of communication are all discussed in detail. Tests are conducted to assess the …

The Effect Of Shot Dependency On Composite Materials Subject To Ballistic Testing, Clayton C. Hankins

Theses and Dissertations

Ballistic analysis was performed on four common composite armor materials: 3k standard modulus plain weave carbon fiber, 8HS satin weave S-glass fiber, plain weave Kevlar® KM2 600 Denier fiber, and Spectra Shield® 4232 ultra-high molecular weight polyethylene to determine shot dependency based upon shot-to-shot impact distance, degree of penetration from the initial impacts, and the delamination effects from the initial impact. The primary measure of ballistic performance was the projectile velocity which represents a 50% probability of penetration, V₅₀. This velocity was determined using a three-phase optimal design test method with an average of twelve shots per test. …

Accelerated Performance Degradation Of Single-Phase Cold Plates For Direct-To-Chip Liquid Cooled Data Centers, Lochan Sai Reddy Chinthaparthy

Mechanical and Aerospace Engineering Theses - Archive

Expanding demands for cloud-based computing and storage, the Internet of Things, and AI-based applications have escalated thermal loads in high-density data centers which necessitated the utilization of more efficient cooling technologies. Direct-to-chip liquid cooling using cold plates has proven to be one of the most efficient methods to dissipate the high heat fluxes of modern high-power CPUs and GPUs. While the published literature has well-documented research on the thermal aspects of direct liquid cooling, a detailed account of reliability degradation is missing. The present investigation provides an in-depth analysis of the reliability degradation of copper cold plates used in high-power …

Creasing Of Polyimide Thin Film For Use In Solar Sails, Andrew Allen

Electronic Theses and Dissertations, 2020-2023

Polymer thin membranes are used in a variety of deployable structures that require large areas and compact stowage. Packaging membrane structures often involves creasing the membrane along predefined fold lines to enforce the desired kinematics under folding action. Inducing permanent deformation by folding to a high curvature is a common method to create creases, particularly in the design of solar sails. The distinct mechanical characteristics at the crease regions have a profound effect on the subsequent deployment and tensioning of the membrane structures. The mechanical and geometric properties at the crease are related to the crease formation process, but the …

Autonomous Guidance Of Unmanned Combat Air Vehicles In Basic Fighter Maneuvering, Jeffery G. Dean

Mechanical and Aerospace Engineering Dissertations - Archive

Basic fighter maneuvering, or BFM, is the dynamic engagement of two or more aircraft in close-range air combat. The relatively recent introduction of advanced unmanned combat air vehicles (UCAVs) has opened the possibility for automated systems to be players in this arena of air-to-air combat, which has thus far been limited to manned aircraft. In order to design an unmanned system that could fight and win a BFM engagement, the system must include an advanced system for guidance. This dissertation leverages techniques from gain scheduling and incorporates adjustable aimpoint guidance, in order to address the capability for UCAVs to execute …

Impact Of Surface And Pore Characteristics On Fatigue Life Of Laser Powder Bed Fusion Ti–6al–4v Alloy Described By Neural Network Models, Seunghyun Moon, Ruimin Ma, Ross Attardo, Charles Tomonto, Mark Nordin, Paul Wheelock, Michael Glavicic, Maxwell Layman, Richard Billo, Tengfei Luo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this study, the effects of surface roughness and pore characteristics on fatigue lives of laser powder bed fusion (LPBF) Ti–6Al–4V parts were investigated. The 197 fatigue bars were printed using the same laser power but with varied scanning speeds. These actions led to variations in the geometries of microscale pores, and such variations were characterized using micro-computed tomography. To generate differences in surface roughness in fatigue bars, half of the samples were grit-blasted and the other half were machined. Fatigue behaviors were analyzed with respect to surface roughness and statistics of the pores. For the grit-blasted samples, the contour …

Fabrication & Mechanical Properties Of Hastelloy-X Matrix Ceramic Composite, Sultan Stewart

Doctoral Dissertations and Master's Theses

In the aerospace industry, there is a desire for increased thermal and mechanical properties of sealing materials. In this thesis, porous Hastelloy-X alloy scaffolds with 80% porosity, currently used for fabricating seals in turbine applications, were used as the base material. The microstructure of the porous Hastelloy-X scaffolds was infiltrated using a room temperature curing silicate colloid (trade name -Dichtol HTWG Hydro #2506) and a novel zirconia based colloid to fabricate the metal matrix composites. Various fabrication processes, some using vacuum and pressure to assist the flow were utilized to infiltrate the scaffolds. The green composites were then cured at …