Aerospace Engineering Commons^™

Numerical Investigation Of Second-Order Effects In A Supersonic Boundary-Layer, Timothy R. Membrino

Master's Theses - Daytona Beach

Historically, the study of boundary-layer flows has centered on the analysis of the first-order boundary-layer equations and their application to physical flow problems. However, selected “real-world” boundary-layer flows exhibit significant second-order effects which are neglected by the first-order equations. Full Navier-Stokes solutions are often not merited or desired for these flows. Therefore, the second-order boundary-layer equations provide a compromise.

Few validating comparisons have been attempted between second-order boundary-layer theory and experimental or numerical solutions of compressible viscous flows. Experimental simulations to capture second-order effects are difficult since the desired effects are small and can exist simultaneously, resulting in a neutralizing …

Nonlinear Analysis Of Composite Beams Under Random Excitations, Snorri Gudmundsson

Master's Theses - Daytona Beach

The vibration responses of three unsymmetrically laminated beams, that are excited with a Gaussian random forcing function, are studied in this thesis. The beams are analyzed nonlinearly and compared to linear results, indicating some important corrections. The solution procedure begins with the derivation of the general equation of motion using Galerkin's method. Then, two approaches are taken in the solution. First, the equation of motion is attacked directly employing a real time Runge-Kutta numerical analysis. Second, the method of equivalent linearization is used. The thesis finds the results from the two approaches to be in a close agreement, although some …

The Professional Air Traffic Controllers Strike: A Retrospective Analysis, Steven E. Durnin

Master's Theses - Daytona Beach

The purpose of this study was to assess the opinions, beliefs, and perspectives of former air traffic controllers who were terminated from employment with the Federal Aviation Administration for participating in the Professional Air Traffic Controllers Organization (PATCO) strike of 1981. The study examines the perceptions of the former controllers to determine their feelings toward the justification for going on strike over 13 years ago. This is relevant in light of recent events including the lifting of the ban against rehiring PATCO controllers by the Clinton Administration.

The data collected for this study were obtained with an opinionnaire mailed via …

Numerical Analysis Of The Viscous Flow In A Supersonic Diffuser, Sa'ed A'Rafat

Master's Theses - Daytona Beach

The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one …

Nonlinear Finite Element Analysis Of Laminated Composite Beams Subjected To Harmonic Excitations Using A 20 Dof Beam Element, Mansour Nosrati Kenareh

Master's Theses - Daytona Beach

The purpose of this thesis is to study the nonlinear analysis of antisymmetrically laminated composite beams including shear deformation subjected to harmonic excitation, using a 20-degree of freedom finite element beam. The beam has 10 degrees of freedom at each node: The axial displacements, the transverse deflection due to bending and transverse shear, the twisting angle, the in-plane shear rotation, and their derivatives along the axial direction. In this study, the effect of different parameters such as damping, shear deformation and different edge conditions on the steady-state frequency-responce will be investigated. The analysis was based on the use of finite …

Nonlinear Forced Vibration Of An Unsymmetrically Laminated Composite Beam, Marie Helene Pompei

Master's Theses - Daytona Beach

The purpose of this thesis is to study the nonlinear forced vibration of an unsymmetrically laminated composite beam. Two cases are considered: unsymmetrical angle-ply and unsymmetrical cross-ply composite beams. The nonlinear governing partial differential equations of motion are obtained by taking into account the von-Karman geometrical nonlinearity. These equations are transformed into nonlinear ODE (Ordinary Differential Equations) by means of the Galerkin method. For both cases the forced Duffing equation was obtained. It is to be noted that only for the unsymmetrical cross-ply laminate simply-supported case are both quadratic and cubic nonlinearities present. The resulting equations for both cases are …

Neural Network Detection Of Fatigue Crack Growth In Riveted Joints Using Acoustic Emission, Adriano F. De Almeida

Master's Theses - Daytona Beach

The purpose of this research was to demonstrate the capability of neural networks to discriminate between individual acoustic emission (AE) signals originating from crack growth and rivet rubbing (fretting) in aluminum lap joints. AE waveforms were recorded during tensile fatigue cycling of six notched and riveted 7075-T6 specimens using a broadband piezoelectric transducer and a computer interfaced oscilloscope. The source of 1,311 signals was identified based on triggering logic, amplitude relationships, and time of arrival data collected from the broad-band transducer and three additional 300 Hz resonant transducers bonded to the specimens. The power spectrum of each waveform was calculated …

Comparison Of Air Traffic Control Candidate Ability With Simulator-Based Training Measures, Lawrence A. Tomaskovic

Master's Theses - Daytona Beach

The purpose of this study was to determine if the utilization of an experimental computer-based selection test battery would aid in the prediction of a candidate's performance when using an air traffic control computer-based simulation program. Each candidate completed the selection test battery, and then received air traffic control instruction using the air traffic control simulation program incorporated in the TRACON/Pro™ simulator system. The selection test battery results were correlated with the subsequent simulator scoring results.

The Effect Of Active And Passive Control On Air Traffic Controller Dynamic Memory, Esa M. Rantanen

Master's Theses - Daytona Beach

The purpose of this study was to investigate the effect of automated and passive control on air traffic controller dynamic memory. The study consisted of two experiments, each involving a realistic ATC scenario for radar approach control with a mix of arriving and departing traffic. In Experiment I, the subjects performed manual control of the traffic while, in Experiment II, the scenario was highly automated and the subjects were tasked with only monitoring the situation. The dynamic memory performance was measured by interrupting the scenario and having the subjects recall the traffic situation at the moment of simulation interruption. The …

Incorporation Of Traffic Collision Alert System (Tcas) Advisories On Heads-Up Displays: Enhanced Pilot Response, Hamadeh A. Nureddine

Master's Theses - Daytona Beach

This study evaluated the effects that heads-up mounted TCAS displays had on pilot response and workload. Pilot response was evaluated by: (a) response time to a traffic advisory, and (b) number of missed traffic alerts. Workload assessment was accomplished in accordance with NASA's Task Load Index (TLX). Subjects were all licensed pilots with a minimum of a private pilot license and an instrument rating. A total of 32 subjects were randomly assigned to experimental and control groups utilizing HUD-mounted, and conventional, TCAS displays respectively. Performance data was collected during computer-simulated flights, while subjective workload levels were reported at the end. …

Low Reynolds Number Laminar Separation Bubble Control Using A Backward Facing Step, Dominique Rothan

Master's Theses - Daytona Beach

The problem of a laminar separation bubble on the upper surface of a 9.5% thick airfoil operated at low Reynolds number (R_N = 380,000) was investigated experimentally.

An unmodified LRN-010 airfoil and a modified LRN-010 airfoil with a backward facing step on its upper surface were built and tested in the ERAU wind tunnel in order to obtain pressure distributions and drag for different angles of attack.

Results were found to be in good agreement with the results obtained from the XFOIL CFD code. It was concluded that the step cutout modification improves the airfoil’s lift-to-drag ratio at low …

Utilizing Instructional Design Constructs To Enhance Computer-Based Instruction In Air Traffic Controller Training, Theodore Scott Rhoads

Master's Theses - Daytona Beach

This study demonstrates that a computer-based instructional design format is appropriate for novice air traffic control (ATC) training. The computer presents the student with small amounts of information in tutorial and drill and practice sequences that necessitate student interactivity. The student is then periodically audit tested to ascertain mastery of the subject matter. The result of these mid-lesson evaluations serve as a self-check so that the student can assess his/her progress in the learning cycle. The systematic design of instruction and interactive approach to learning, enhances student motivation, improves learning and retention, while placing the responsibility of achieving specific learning …

Thermally Induced Vibration Of A Cross-Ply Laminated Plate With Hygrothermal Effects (Exact Solution), Stephen Jerry Maerz

Master's Theses - Daytona Beach

Of increasing importance in structural design is the use of fiber-reinforced polymeric composite material, notably in advanced aircraft and projectiles. These applications expose the materials to varied environmental conditions, therefore the material performance under these conditions is of great interest. One aspect of this is the solution of the dynamic response of a composite structure under elevated temperature and moisture conditions. An exact solution is formulated which describes the hygrothermal effects due to heating and moisture diffusion on one surface of a symmetric cross-ply plate made of AS/3501 graphite epoxy with simply-supported boundary conditions.

Isolating Failure Mechanisms In A Fiberglass/Epoxy Tensile Test Specimen Using Acoustic Emission Signal Parameters, Michael Kouvarakos

Master's Theses - Daytona Beach

This study used acoustic emission (AE) signal parameters to isolate the failure mechanisms in a 0° unidirectional, fiberglass/epoxy tensile test specimen. Since several failure mechanisms were known to be present, the lack of any distinctly identifiable bands in the original amplitude distribution indicated that there was considerable overlap between the AE signals of the various failure mechanisms. In order to separate the amplitude bands associated with each mechanism, it was necessary to sort on the duration of the AE signal. Two additional plots, counts versus amplitude and hits versus counts, were used to verify that the amplitude distributions were comprised …

Thermal Post-Buckling And Vibration Analysis Of Thermally Buckled Antisymmetrically Laminated Beams Using A 20 Dof Finite Element, Misao Mizuno

Master's Theses - Daytona Beach

The purpose of this study is to use the finite element method to analyze thermal buckling, post-buckling, and vibrations of thermally buckled composite beams including shear deformation. The beam element used has ten degrees of freedom at each node: axial displacement, transverse displacement due to bending and shear, twisting angle, inplane shear rotation and their derivatives with respect to x. Hermitian polynomials and Lagrange's equation were used to derive the equations of motion. The equations of motion were divided into static and dynamic parts. For buckling analysis, the eigenvalue problem was solved for the critical temperature. The scaled first mode …

Determination Of The Parameter Limits For Artificial Non-Random Microwave Signal Detection, Irvin Lee Burough

Master's Theses - Daytona Beach

The Doppler shift of small bandwidth (several Hertz) microwave signals makes identification of spectral features difficult; the Doppler individual bandwidth shift can be a factor of hundreds or thousands of times greater than the bandwidth. A computer model supplied by the National Aeronautics and Space Administration's (NASA) Search for Extra-Terrestrial Intelligence (SETI) project, which can simulate radio frequency interference (RFI) and a buried ETI signal, will determine the limits of the signal-to-noise ratio (SNR) and false alarm threshold for identification of the signal after Doppler shifting. By running the model on a MicroVAX II computer, it will be possible to …

An Investigation Of The Floor Attachment Assembly Of A Large Transport Aircraft Seat Subjected To Crash Dynamic Loadings, Mark William Creager

Master's Theses - Daytona Beach

Accident investigations by the National Transportation Safety Board concluded that the passenger seat and restraint systems found in today's aircraft used by the airlines are inadequate to protect the occupant in airplane crashes. Computer models were developed of the seat-track assembly and finite element analyses were performed subjected to crash dynamic loadings. The seat-track interface was modeled with gap elements to accurately model the geometric interaction between the track and seat-track fittings. Results showed large deformations and stresses above yielding in both the seat and track when subjected to accelerations prescribed for certification under the Federal Aviation Administration (FAA) regulations.

Cognitive Learning Styles And Their Relation To Air Traffic Control Screening And Training, Vincent P. Galotti

Master's Theses - Daytona Beach

The purpose of this study was to show a relationship between the type of cognitive learning style that an individual possesses and their subsequent success at simulated air traffic control practical exercises. Kolb's Learning Style Inventory was utilized to determine dominant learning styles of 30 college students enrolled in a laboratory-based air traffic control course. The instrument was administered during the first day of classes in the Fall of 1990. Students were placed in one of four groups for statistical purposes according to learning style. The scores of simulated micro-computer based air traffic control practical exercises given at semester's end …

Investigation Of The Effects Of Geometry On The Efficiency Of The Double Lap Joint Of Unidirectional Fiberglass Composites, Joseph Anthony Musco

Master's Theses - Daytona Beach

The fracture toughness in shear mode (Mode II) has been studied for double lap adhesive joints where geometry of the joint is the major parameter. A unidirectional fiberglass - epoxy system was selected for experimental tests and theoretical analysis. Both rectangular and elliptical planform geometries were investigated. In order to evaluate the results, the adhesion area of the two geometries was purposely made identical. Through computer analysis, the effects on the stress concentration factor as a function of geometry was investigated. Then, using testing and fracture mechanics techniques, calibration factors for Mode II loading of the two geometries were obtained. …

Effect Of Acoustic Oscillations On The Burning Of Carbon, Vivek Lall

Master's Theses - Daytona Beach

This study is concerned with the investigation of the effect of oscillatory flow on the burning of carbon. This involves the study of two separate problems. The first is to obtain a solution for combustion of a carbon particle surrounded by a stationary gaseous film, and the second is to obtain a solution for combustion of the carbon particle subjected to acoustic oscillations. A computer program is developed to solve the governing equations of both problems. Comparison of the solutions to the steady and the oscillatory cases provides information on the effect of the oscillations on carbon particle combustion.

Various …

Composite Structure Ultimate Strength Prediction From Acoustic Emission Amplitude Data, James Lewis Walker Ii

Master's Theses - Daytona Beach

The acoustic emission (AE) given off by a structure as it is stressed provides a passive means to characterize flaw growth activity in complex structures. This thesis demonstrates how the qualitative analysis of AE data can be refined to provide a quantitative tool for predicting the ultimate strength of composite tensile test specimens. From an original sample set of only six specimens, a multivariate statistical analysis was used to generate an ultimate strength prediction equation. The variables of the multivariate statistical analysis were obtained through the mathematical modeling of the specimen’s AE amplitude distributions produced during proof testing. Ultimate strengths …

The Development And Application Of A Trapezoidal Shear Panel For Use In Finite Element Codes, Glenn P. Greiner

Master's Theses - Daytona Beach

This thesis documents the efforts of the writer and his colleagues over the past several years to improve the theoretical foundation of the arbitrary quadrilateral shear panel used in structural analysis codes to model aircraft structures. An equilibrium stress-based element with pure shear resultants on its sides was developed using the principle of complementary virtual work. The internal stress field was derived from a complete polynomial Airy stress function. The element was numerically tested as a pure stress element and a hybrid element to assess the deflection properties for highly distorted planar panels. Linear-stress and quadratic-displacement rods were used, as …

Optimized Engine Out Procedures To Extend The Range Of Jet Transport Airplanes, Miltos Miltiadous

Master's Theses - Daytona Beach

The purpose of this study was to develop optimum engine-out procedures for the Boeing 747 and 767 on extended flights that will increase the range of the aircraft in case of engine failure. Theory suggests that an optimum amount of bank angle that will minimize drag resulting from asymmetric thrust in a multiengine airplane experiencing an engine failure, can be determined. By banking the airplane into the operative engines by that optimum bank angle, the range of the airplane can be improved significantly. Wind tunnel tests of both a Boeing 747 and a 767 model were performed to determine experimentally …

Aerodynamic Forces On Flight Crew Helmets, Timothy A. Sestak, Richard M. Howard, Chester A. Heard

Publications

Wind tunnel tests were conducted to deter- mine the aerodynamic forces generated on aircrew flight helmets. Three helmets were tested: two used by aircrews flying ejection seat aircraft in the U.S. military, the Navy HGU-33/P and the Air Force HGU-53/P; and one prototype helmet of significantly different shape and volume. Axial and normal forces were measured through a range of pitch and yaw angles. It was found that large forces exist tending to promote helmet loss during ejection, and that simple modifications to the current helmet configurations can reduce those forces by as much as 40%. It is demonstrated that …

Data Reduction Procedure For An Experimental Method Of Measuring The Velocity-Coupled Response Function Of Solid Propellants, William H. Jarvis

Master's Theses - Daytona Beach

A computer program has been developed for calculation of the velocity-coupled response function of solid-propellants from experimentally measured pressure data. The proposed velocity-coupled response function measurement apparatus consists of an end-burner combustor where the propellant sample is oscillated in a direction normal to the flow in the presence of a standing acoustic wave within the combustion chamber. The pressure measurements are made at select points along the length of the chamber.

The data reduction program consists of a Runge-Kutta routine driven by a BFGS multivariable search routine. The Runge-Kutta routine determines the pressure distribution within the chamber of the proposed …

Predicting Burst Pressures In Filament Wound Composite Pressure Vessels Using Acoustic Emission Data, Frederick R. Kalloo

Master's Theses - Daytona Beach

This work presents a statistical method for predicting the burst pressures in filament wound composite pressure vessels by analyzing acoustic emission data obtained during hydroproof testing. First the acoustic emission data is plotted in the form of amplitude distributions. Then, by using statistical models with characteristics similar to Rayleigh and Gaussian distributions, failure mechanism percentages are found, at which point multiple regression analysis is used to predict burst pressures. Next, the predicted burst pressures are compared to the actual burst pressures and the significance of the data is analyzed using standard statistical theories. The research shows that the predicted burst …

A Kinematical Investigation Of Some External Wind Tunnel Force Measurement Systems, Gary A. Peterson

Master's Theses - Daytona Beach

A discussion on the fundamental concepts associated with wind tunnel forces measurement systems (balances) is presented. Detailed static analyses are performed on the six component pyramidal, six component floating beam, and three component strain gaged strut balances. These static analyses lead to a dimensional uncertainty investigation of the pyramidal and strain gaged strut balances. The critical dimensions for the pyramidal balance are found to be the lengths of the pyramidal links, like platform half-width, and the model attachment strut. No single dimension on the strain gaged strut is more critical than the others.

A new method for the classification of …