Aerospace Engineering Commons^™

Modeling Launch Vehicle Success Using Artificial Neural Networks, Jennifer A. Schuck

Master's Theses - Daytona Beach

Expendable launch vehicles in the United States currently have a reliability of 92%. The failures that do occur cost millions of dollars in spacecraft replacement, lost revenue, and other expenses. These costs are passed on in higher insurance rates and launch vehicle price. If the launch outcome of the launch vehicles could be better predicted, the overall cost of launching payloads into space would decrease. This study used artificial neural networks to model the overall launch outcome of a launch vehicle so that the results of a launch could be predicted. Two neural network architectures--MLP and fuzzy ARTMAP--were trained on …

Neural Network Fatigue Life Prediction In 7075-T6 Aluminum From Acoustic Emission Data, Emeka Chigozie Ibekwe

Master's Theses - Daytona Beach

The objective of this research was to classify acoustic emission (AE) -data associated with fatigue cracks in aluminum fatigue specimens and to use early cycle life AE data to predict failure in such members. An AE data acquisition system coupled with a Kohonen self organizing map and a back propagation neural network were used to perform the analysis. AE waveforms were recorded during fatigue cycling of twenty-four notched 7075-T6 aluminum specimens using broad-band piezoelectric transducers. A Kohonen self organizing map was used to classify the AE flaw growth signals. The signals were classified into three categories based on their AE …

Ultimate Strength Prediction In Fiberglass/Epoxy Beams Subjected To Three-Point Bending Using Acoustic Emission And Neural Networks, Michele D. Dorfinan

Master's Theses - Daytona Beach

The research presented herein demonstrates the feasibility of predicting ultimate strengths in composite beams subjected to 3-point bending using a neural network analysis of acoustic emission (AE) amplitude distribution data. Fifteen unidirectional fiberglass/epoxy beams were loaded to failure in a 3-point bend test fixture in an MTS load frame. Acoustic emission data were recorded from the onset of loading until failure. After acquisition, the acoustic emission data were filtered to include only data acquired up to 80 percent of the average ultimate load.

A backpropagation neural network was constructed to predict the ultimate failure load using these AE amplitude distribution …

An Analysis Of Intention Formation As A Function Of Prospective Memory In Air Traffic Controllers, Jennifer Nagle

Master's Theses - Daytona Beach

Prospective memory, or memory for future intents, is an important part of everyone's daily life. Air traffic controllers whose jobs are based in an environment that taxes their memory resources for extended periods of time rely on this type of memory. Controllers objectives often change based on incoming information and the amount of traffic they are controlling. It is important to investigate how controllers form intentions for future events, what processes facilitate retrieval of this information, and establish what influence experience may have. This study proposes to assess controllers in an air traffic scenario by employing a cognitive task analysis …

Improving The Capability Of Preliminary Aircraft Design Methodology By Incorporating Numerical Methods Into Segments Of A Proven Statistical Method, Igor Lebovic

Master's Theses - Daytona Beach

The purpose of this study was to identify any potential limitations of Roskam’s statistical aircraft flight performance estimation method, and to provide processes capable of improving those limitations. This project was conducted in collaboration with Diamond Aircraft Industries, and as any other general aviation manufacturer with limited time, manpower, and financial resources, Diamond wants the new process to be time and cost-effective. Presented in this study is a computational alternative that combines the speed and accuracy of low-order panel methods with the fully-coupled viscous/inviscid interaction method from the ISES code that was developed by Drela and Giles. Its benefit is …

Development & Validation Of The Acoustic Analogy Code For Jet Noise Predictions, Leonardo A. Bueno-Benitez

Master's Theses - Daytona Beach

In this thesis, the numerical code for predicting the far-field sound radiated from a localized sound source is developed based on Lighthill's acoustic analogy theory. The acoustic analogy equation allows calculating the sound intensity in terms of the integral over the volume with distributed Lighthill tensor of unsteady flow fluctuations. A FORTRAN code is written to perform the integration using Simpson's numeric technique. The procedure for validating the code against the test case for the sound source in the form of a Gaussian pulse is examined. Future application of the code to predict acoustic radiation from turbulent jets is briefly …

Vibration Analysis Of A Fan/Compressor Blade, Daisaku Inoyama

Master's Theses - Daytona Beach

The vibration of blades in gas turbine engines has become an important issue during the last decade because of its significant impact on high cycle fatigue failure due to resonant vibrations. The main objective of this thesis is the vibration analysis of compressor/fan blade using three-dimensional finite element analysis together with various analytical approaches. First, the analytical solutions were established using various analytical methods, Bernoulli-Euler, Rayleigh, Rayleigh-Ritz, two-dimensional plate, and Timoshenko beam methods. Then, the vibration behaviors of the blade are analyzed in full extent using commercially available finite element solver, MSC.NASTRAN, and correlated with the analytical solutions. The finite …

A Full-Wave Investigation Of The Use Of A 'Cancellation Factor' In Gw-Airglow Interaction Studies, Yonghui Yu

Master's Theses - Daytona Beach

Atmospheric gravity waves (GWs) perturb minor species involved in the chemical reactions of airglow emissions in the mesopause region of the earth's atmosphere. The so-called 'Cancellation Factor' (CF) is defined as a transfer function relating the amplitude of airglow brightness fluctuation to the amplitude of GW-induced fluctuation in temperature [Swenson and Gardner, 1998]. This transfer factor can be used to determine GW fluxes and the forcing effects of GWs on the mean state through airglow observations, because GW fluxes are proportional to the square of GW amplitude.

Numerical models [Walterscheid et al., 1987; Schubert et al., 1991] have previously shown …

Microburst Recovery For Jet Transport Aircraft: A Comparison Between Constant And Variable Pitch Guidance Trajectories, Mark Cadmus

Master's Theses - Daytona Beach

The purpose of this research was to compare, in a simulator, the safety of a variable pitch strategy with the established constant pitch strategy in transitioning through a microburst during an abort maneuver in the approach to landing phase of flight. In numerous mathematical and computer studies of microburst penetrations, the variable pitch strategy provided a greater recovery altitude than the constant pitch strategy. A Boeing 737 level C aircraft simulator was employed to evaluate these findings in a dynamic environment. Three appropriately qualified subjects piloted 35 flights through a microburst, while computer generated data were collected. "Safety", defined as …

An Original Method For Computing Complex Non-Premixed Flows In Chemical Equilibrium, Raphael Cioffl

Master's Theses - Daytona Beach

A novel method for computing chemical equilibrium reactions in three-dimensional reacting fluid flows is introduced in this paper. The originality of the method is that continuity equations are solved for the atomic densities rather than for the molecular species densities, as is the case for non-equilibrium flow calculations. The method is suited for applications to mixing flows in rocket engine combustors, where, due to the typical low convective speed, chemical reaction is best modeled as an equilibrium process. Equilibrium formulations usually describe the flow as a perfect, atomically uniform mix between the fuel and the oxidizer. This assumption tends to …

Special Article. Space Security In A World Of Security And Insecurity, Ibpp Editor

International Bulletin of Political Psychology

This article provides a theoretical analysis from which a space security expert could appreciate the complexity and richness of the space security challenge.

A History Of Space Security, Ibpp Editor

International Bulletin of Political Psychology

This article provides a conceptual infrastructure for thinking about the history of space security.

Numerical Analysis Of An Airfoil Response To An Impinging Gust, Claire M. Lessiau

Master's Theses - Daytona Beach

The BASS code, a nonlinear high-order prefactored compact code is validated on a benchmark problem. The nonlinear response of a loaded airfoil to an impinging vertical gust is investigated in the parametric space of gust intensity and frequency. Computational resources, involving a Linux cluster, were set up and maintained. The code was corrected and adapted to this particular problem. Results are compared with linear solution from the GUST3D solver.

Development Of A Force And Airspeed Data Acquisition System For The Embry-Riddle Aeronautical University 30x40 In. Subsonic Wind Tunnel, Toon Hong Foo

Master's Theses - Daytona Beach

The very first objective of performing most experiments is collecting numerical data. Values can be read from instruments or gauges by eye and recorded by hand. However, in certain experiments the amount of data collected may become so large that a human alone can not observe and record the data fast enough. This is where a data acquisition system comes into play. A data acquisition system is a network of devices that collects data from instruments and outputs it to hard copies or storage devices. A data acquisition system can also control instruments to take the data at the exact …

Residual Compressive Strength Prediction Of Carbon/Epoxy Laminates Subjected To Low Velocity Impact Damage, Christopher D. Hess

Master's Theses - Daytona Beach

Low energy impact damage to a composite structure is difficult to detect and can have profound effects on compressive strengths. Low energy impact damage is sometimes termed as barely visible impact damage (BVID). Detecting BVID is only possible by implementing nondestructive testing (NDT) techniques. Depending upon the support conditions, material system, laminate thickness, lay-up orientation, and impactor geometry, velocity, and hardness, the types of damage associated with BVID include delaminations, longitudinal and transverse matrix cracks, and in some cases, fiber breaks. Material properties such as the strengths of the matrix, fibers, fiber/matrix interface, and more important for BVID, ply interface …

The Effectiveness Of Monitor-Based Augmented Reality Paradigms For Learning Space-Related Technical Tasks, Christopher Michael Opalenik

Master's Theses - Daytona Beach

Currently today there are many types of media that can help individuals learn and excel in the on going effort to acquire knowledge for a specific trait or function in a workplace, laboratory, or learning facility. Technology has advanced in the fields of transportation, information gathering, and education. The need for better recall of information is in demand in a wide variety of areas. Augmented reality (AR) is a technology that may help meet this demand. AR is a hybrid of reality and virtual reality (VR) that uses the three-dimensional location viewed through a video or optical see-through media to …

Torque Limit Of A Mechanical Fastener In A Graphite/Epoxy Joint, Kristian M. Kostreva

Master's Theses - Daytona Beach

Presently there is a lack of confidence amongst engineers when specifying the preload of a mechanical fastener in a composite joint due to a lack of a fundamental knowledge base regarding the behavior of composites under fastener compressive load. As such, a novel experimental procedure was developed herein to determine the through-the-thickness compressive (TTTC) material properties. A total of 206 property tests were performed on four different graphite/epoxy material systems. The results confirmed that TTTC material properties vary with fiber orientation, laminate thickness, fiber volume fraction, and even laminate surface finish. Hence, the 'rule of mixtures' provides a poor estimate …

Modeling Of Acoustic Emission Failure Mechanism Data From A Unidirectional Fiberglass/Epoxy Tensile Test Specimen, Daniel R. Lendzioszek

Master's Theses - Daytona Beach

The purpose of this work was to model the acoustic emission (AE) flaw growth data that resulted from the tensile test of a unidirectional fiberglass/epoxy specimen. The data collected and stored during the test were the six standard AE quantification parameters for each event. A classification neural network was used to sort the data into five failure mechanism clusters. The resulting frequency histograms of the sorted data were then mathematically modeled herein using the three types of Johnson distributions: bounded, lognormal, and unbounded. These provided a reasonably good fit for all six AE parameter distributions for each of the five …

An Experimental Investigation Of Direct And Indirect Viewing Of A Remote Manipulation, Stephen N. Plishka

Master's Theses - Daytona Beach

The purpose of this study was to evaluate direct and indirect viewing of a remote manipulation. With continued exploration of inner and outer space, the ability to directly manipulate objects is lost due to the nature of operating in harsh environments. Remote viewing and operation of equipment is used in such things as the space shuttle manipulator arm, orthoscopic surgery, undersea exploration, and hazardous material management. Most of these operations do not have the luxury of direct viewing. This study will compare the effects of direct viewing vs. indirect viewing from three different viewing distances of 20cm, 60cm and 100cm.

Acoustic Emission For Periodic Inspection Of Composite Pressure Vessels, Bao Rasebolai Mosinyi

Master's Theses - Daytona Beach

Cost savings can be achieved in a wide range of applications by replacing the current procedure for hydrostatic recertification of high-pressure composite gas cylinders with acoustic emission (AE) nondestructive testing. Advantages of AE recertification over the current hydrostatic method include: (1) no water contamination, since pressurization of the cylinders is done with air as opposed to water; (2) the risk of damage is decreased since the test pressure is reduced from 166% of design pressure to 110% of operating pressure; (3) the ability of acoustic emission to detect and locate flaws increases safety; and (4) the in-situ method will reduce …

Low Proof Load Prediction Of Ultimate Strengths Of Fiberglass/Epoxy I-Beams Using Acoustic Emission, Edward C. Fatzinger Jr.

Master's Theses - Daytona Beach

Acoustic emission (AE) nondestructive testing was used to monitor fiberglass/epoxy I-beams. The experiment consisted of loading the I-beams in cantilever fashion with a hydraulic ram. While testing, AE waveforms were collected from the onset of loading to failure. After acquisition, the AE data from each test were filtered to include only data collected up to 50% of the theoretical ultimate load for further analysis.

A Kohonen self-organizing map was utilized to separate each individual data point (hit) into failure mechanism clusters. Then a multiple linear regression analysis was performed using the percentage of hits associated with each failure mechanism along …

Design And Construction Of A 1/3-Scale, 1986 Cessna 172p Flight-Test Aircraft, Michael J. Hinton

Master's Theses - Daytona Beach

The incredible cost of prototype flight testing can be a very limiting factor in the optimization of new designs as they proceed from the drawing board to the flight line. The use of low-cost scaled models to predict full-scale prototype performance is the focus of this project. It will be shown that by strictly following geometric and dynamic scaling criteria, the scaled aircraft's flight performance can be predictably related to the full-scale aircraft's performance. Many companies have performed scaled flight-testing of Remotely Piloted Vehicles (RPV's) and there is much speculation as to the results of these tests, but non-proprietary information …

Solving Nonlinear Aeronautical Problems Using The Carleman Linearization Method, Brian William Gaude

Master's Theses - Daytona Beach

Many problems in aeronautics can be described in terms of nonlinear systems of equations. Carleman developed a technique to linearize such equations that could lead to analytical solutions of nonlinear problems. Nonlinear problems are difficult to solve in closed form and therefore the construction of such solutions is usually nontrivial. This thesis will apply the Carleman linearization technique to three model problems: a two-degree of-freedom (2DOF) ballistic trajectory, Blasius' boundary layer, and Van der Pol's equation and evaluate how well the technique can adequately approximate the solutions of these ordinary differential equations.

Optimization Of Flow Quality In The Test Section Of The 30-Inch X 40- Inch Subsonic Tunnel, Ahmed F. Elnenaey

Master's Theses - Daytona Beach

The purpose of this study is to optimize the flow quality inside the 30-inch x 40-inch subsonic wind tunnel. The tunnel is an open circuit with its inlet positioned adjacent to the side door of the lab; forcing the air to make a ninety degrees turn entering the tunnel. The flow suffered from two main deficiencies, high level of turbulence and slightly unsteady flow with a non-uniform velocity distribution across the test section. By utilizing a hot-film anemometer system and a total pressure rake, turbulence and velocity distribution data were obtained. Rounded corners and a turning vane were installed in …

Book Review: Space Shuttle: The History Of The National Space Transportation System: The First 100 Missions, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Space Shuttle : the History of the National Space Transportation System: the First 100 Missions by Dennis R. Jenkins. Voyageur Press, 2001 513p, 0-9633974-5-1 $39.95.

Combined Loading Of Composite Box-Beams With Linearized Differential Equations Of Motion, Michael Alan Dupuis

Master's Theses - Daytona Beach

The purpose of the following analysis is to develop a method for determining vertical, horizontal, and torsional displacements of arbitrarily laminated, cantilevered composite box-beam under static, transverse loading. Small deflections are assumed and the differential equations of motion have been linearized for ease of calculation. The Smith and Chopra stiffness matrix is used in the equations of motion, and software was written to solve for the stiffness matrix elements. Comparisons are made with bending slope solutions from previously published results, and the presented analysis is compared to empirical results of a composite box-beam under tip loading. Finally, an example solution …

An Ameliorated Prediction Of The Empennage In-Flight Gust Loads For A General Aviation Aircraft, Philippe Marchand

Master's Theses - Daytona Beach

Airplanes often operate beyond their original design load profiles. Aviation opens so many new possibilities and wide variety of possible activities that it is hard for designers to foresee all loading spectra that the airplane structure will experience throughout its life. Nevertheless, the aircraft structures are required to be designed to failsafe or safe-life criteria to be certified by the FAA. AFS-120 provides a database of normal accelerations that can be used to derive airplane wing loads. ACE-100 describes an acceptable method for determining the fatigue life of an empennage based on the same normal acceleration data provided in AFS-120. …

Nonlinear Analysis Of Unsymmetric Laminates Under Cylindrical Bending, Eun Seon Park

Master's Theses - Daytona Beach

Nonlinear analysis of unsymmetric composite long, narrow laminates under cylindrical bending is studied. The nonlinear governing equations are obtained to analyze the cylindrical bending of arbitrary laminates. The von-Karman type geometrical nonlinearity is incorporated in the governing equation. The shear effect between lamina is further considered in the governing equation. The solution is obtained for different boundary conditions. The results of arbitrary angle-plies are discussed. Unidirectional prepreg graphite-epoxy is considered for numerical results.

Lidar Observations Of Elevated Temperatures In Bright Chemiluminescent Meteor Trails During The 1998 Leonid Shower, Xinzhao Chu, Alan Z. Liu, George Papen, Chester S. Gardner

Physical Sciences - Daytona Beach

Seven persistent trails associated with bright fireballs were probed with a steerable Na wind/temperature lidar at Starfire Optical Range, NM during the 17/18 Nov peak of the 1998 Leonid meteor shower. These chemiluminescence trails were especially rich in Na. The average Na abundance within the trails was 52% of the background Na layer abundance, which suggests that the corresponding masses of the meteors were from 1 g up to 1 kg. CCD images show that the chemiluminescent emissions (including Na and OH) are confined to the walls of a tube, which expands with time by molecular diffusion. Lidar profiles within …

The Static Thrust Characterization Of The Quatra Aerrow Q100xl Engine For Flight Performance Prediction Of The 1/3-Scaled Cessna 172p Model, Joon Fui Ho

Master's Theses - Daytona Beach

The purpose of this research is to predict the thrust as a function of forward flight velocity required for the one-third-scaled Cessna 172P. This model was designed to verify scaling laws. Therefore, it is important that it be aerodynamically scaled and that it have similar thrust characteristic as that of the full scale Cessna 172P. Several propellers and two Quatra Aerrow Q100XL two-cycle engines were acquired for this research project. Three propellers were selected to undergo a series of static thrust testing. The measured static thrust was then used to predict the flight performance of each tested propellers with the …