Aerospace Engineering Commons^™

Effects Of Foreign Object Damage From Small Hard Particles On The High-Cycle Fatigue Life Of Ti-6a1-4v, Joseph L. Hamrick Ii

Theses and Dissertations

Thin rectangular samples of Ti-6Al-4V were damaged by four methods to represent foreign object damage found in turbine engine blades: 1) impact with 2 mm and 5 mm diameter glass spheres at 305 m/s, 2) impact with 2 mm and 4 mm diameter steel spheres at 305 m/s, 3) quasi-static displacement controlled indentation using steel chisels with 1 mm, 2 mm and 5 mm diameter tips and 4) shearing notches with a 2 mm diameter chisel point under a quasi-static loading condition. Finite element analysis was used to study the relationship between the stress state created by the plastic damage …

Reverse Engineering Of Foreign Missiles Via Genetic Algorithm, Jon D. Wollam

Theses and Dissertations

One mission of the National Air Intelligence Center (NAIC) is the reverse engineering of foreign missile weapon systems from incomplete observational data. In the past, intuition and repeated runs of a missile performance model were required to converge to a solution compatible with observed flight characteristics. This approach can be cumbersome and time consuming, as well as being subject to undesirable influences from the analyst's preconceptions and biases. An alternative approach has been created to apply genetic algorithm (GA) techniques to allow automation of the process, wider exploration of the design space, and more optimal solutions matching the observational data. …

Current Design - Structure And Layout, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Current Design - Structure and Layout" from November 30, 1999.

Opal Press Release: October 28, 1999, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A press release written by Professor Bob Twiggs titled "Opal Press Release: October 28, 1999."

Opal Microsatellite, Greg Hutchins

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Greg Hutchins on the "OPAL Microsatellite" from October 8, 1999.

Student Space Program: Stanford University, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Student Space Program: Stanford University" from October 3, 1999.

Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani

Chemistry Faculty Research & Creative Works

Mechanical testing and surface fractography were used to characterize the fracture of E-glass fiber reinforced epoxy composites as a function of the silane coupling agent used. gamma-Aminopropyltriethoxysilane (APS) and delta-aminobutyltriethoxysilane (ABS) were used because these have been shown to have different interfacial mobilities at multilayer coverage. The values of the properties studied generally increased from untreated c, as determined from a Mode I translaminar fracture toughness tests, for the untreated composites (10.5 ± 0.4 kJ/m2) was lower than that for the ABS-treated composites (14.3 ± 2.1 kJ/m2) which was lower than that for the APS-treated composites (17.1 ± 2.4 kJ/m2). …

Darpa Mems Demonstration In Systems Of Dod Relevance, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "DARPA MEMS Demonstration in Systems of DoD Relevance" from October of 1999.

An Intermittent-Combustion General Aviation Aircraft Engine Exhaust Noise Prediction Algorithm, Hiroko Tada

Master's Theses - Daytona Beach

From an environmental point of view, the reduction of aircraft noise has become an important factor recently. There are two factors that make airplane noise: propeller noise and engine noise. This report puts emphasis on only the engine noise in order to begin understanding what airplane engine exhaust noise is. At first, the engine exhaust noise is comprehended using the Dobrzynski's engine noise theory. Next, a discussion about an Embry-Riddle Aeronautical University (ERAU) engine system, engine exhaust system configurations, and microphone setting standards that show the ERAU engine system exhaust noise data. Finally, an Intermittent-Combustion (IC) General Aviation (GA) aircraft …

Suppression Of Post-Buckling Deflection And Panel-Flutter Using Shape Memory Alloy, Mohammad Tawfik Abo El So-Oud

Mechanical & Aerospace Engineering Theses & Dissertations

A novel concept proposed is the use of Shape Memory Alloy (SMA) to reduce the panel thermal deflection and flutter responses. SMA has unique ability to recover large prestrains completely when the alloy is heated (by aerodynamic heating in the present case) above the austenite start temperature A_s. During the recovery process, a large tensile recovery stress occurs if the SMA is restrained.

In this thesis, a panel subject to the combined aerodynamic and thermal loading is investigated. A nonlinear finite element model based on von Karman strain displacement relation is utilized to study the effectiveness of SMA …

An Improved Thermal Mass Flow Controller For Hazardous And Precision Applications, William J. Alvesteffer

Mechanical & Aerospace Engineering Theses & Dissertations

A new mass flow controller has been designed which responds very rapidly to changes in control settings. The design was evolved after carefully studying the internal flow and the sources for thermal lag and other non-linear behavior. After discussing an overview of the basic mass flow controller operating principles, data will be presented which characterize the basic building blocks of an advanced flow sensor design. Subsequently, a flow model and control strategy have been developed and tested which reduce response lag significantly. Results of the new design, obtained experimentally under various transient conditions, will be discussed.

Long-Term Aircraft Structural Integrity Prediction Under The Influence Of Feedback Control, Si-Bok Yu

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis investigates the influence of feedback control, and other factors associated with loading characteristics, on fatigue damage reduction and long-term integrity of aircraft structural components. An actively controlled flexible aircraft model and a new state space modeling procedure for crack growth are utilized to uncover important factors which influence airframe crack growth. A matrix of simulation test cases is constructed to cover such variables as open-loop operation, nominal closed-loop operation, perturbed closed-loop operation (i.e., feedback gain variation), nominal maneuver profile, perturbed maneuver profile (including overload strength and frequency), atmospheric gust, and mean stress level. Simulation output data including crack …

Microsatellite And Formation Flying Technologies On University Nanosatellites, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A published article that included Professor Bob Twiggs as an author titled "Microsatellite and Formation Flying Technologies on University Nanosatellites" from September 28, 1999.

Arliss: Student Payload Rocket Launch, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A report believed to have been written by Professor Bob Twiggs on the "Student Payload Rocket Launch" from September 10-11, 1999.

The Conference Proceedings Of The 1999 Air Transport Research Group (Atrg) Of The Wctr Society, Volume 3, Anming Zhang, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 99-7

The Conference Proceedings Of The 1999 Air Transport Research Group (Atrg) Of The Wctr Society, Volume 4 , Anming Zhang, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 99-8

The Conference Proceedings Of The 1999 Air Transport Research Group (Atrg) Of The Wctr Society, Volume 2 , Anming Zhang, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 99-6

Space-Available Transportation: An Analysis Of The Cost Of Providing 'Free' Travel, Frank J. Long

Theses and Dissertations

The purpose of this study is to estimate the costs borne by the government for providing space-available travel to eligible uniformed services personnel and their dependents. As the primary provider of the space-available privilege, it is important that the Air Force have an estimate of the burden that the administration of that privilege places on the budget. In January 1993, the Air Force discontinued its 15-year-old practice of charging a fee for space-available travel aboard AMC-owned or controlled aircraft. The fee had been set at $10 in 1978 and was collected to recover a portion of the costs associated with …

University Nanosatellite Distributed Satellite Capabilities To Support Techsat 21, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A published article that included Professor Bob Twiggs titled "University Nanosatellite Distributed Satellite Capabilities to Support TechSat 21" from August 23, 1999.

Active Local Volume Displacement Cancellation Of A Vibrating Baffled Beam, Marcellin Zahui

Dissertations

An active noise control apparatus is developed. The device reduces the sound radiated from a vibrating clamped beam. The attenuation of the sound field is obtained through minimization of local volume displacements of the vibrating beam. Two single-input/single-output cancellation devices are used. Each device employs a motion sensor and an acoustic actuator. The actuator is a loudspeaker equipped with a pressure sensor to detect its volume displacement. The motion sensor signal is related to the local volume displacement of the structure which is then reduced by a loudspeaker driven with an equal but opposing volume displacement. The volume displacement sensors …

The Emerald Nanosatellite Mission, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "The Emerald Nanosatellite Mission" from July 22, 1999.

Designed Reduction Of Radiated Noise Characteristics From Two-Bladed General Aviation Propellers, Chandra K. Stich

Master's Theses - Daytona Beach

In recent years increased public awareness has made the reduction of environmental noise pollution a top priority for the aviation industry. Utilizing current technology, this study examines the reduction of noise generated by two bladed general aviation propellers, through design. The Aircraft Noise Prediction Program - Propeller Analysis System (ANOPP-PAS) is used to predict the noise and performance characteristics for an industry typical reference propeller as well as for the final quiet and efficient design.

This investigation is based on the use of a 200 hp engine rotating a 76 inch propeller. Typically, such a propeller would be rotated at …

Jet Stability And Noise Computations Using Direct Numerical Simulation, Farouk Owis

Mechanical & Aerospace Engineering Theses & Dissertations

The computations of axisymmetric jet noise with symmetric disturbances are investigated using the direct numerical simulation of the unsteady compressible Navier-Stokes equations. High order accurate numerical schemes are employed for the solution of the governing equations. The investigation shows that MacCormack schemes with operator splitting and minimum dispersion error can be used to predict noise radiated from subsonic and supersonic jets with low and high Reynolds numbers. In addition, different kinds of nonreflecting boundary conditions are used at the inflow and outflow boundaries. These boundary conditions include characteristic boundary conditions, buffer domain technique and perfectly matching layer method. The results …

Large Amplitude Pitching Of Supermaneuver Delta Wings Including Flow Control, Yahia A. Abdelhamid

Mechanical & Aerospace Engineering Theses & Dissertations

The unsteady, three-dimensional Navier-Stokes equations are solved to simulate and study the aerodynamic response of a delta wing undergoing large amplitude pitching motion up to 90° angle of attack. The primary model under consideration consists of a 76° swept, sharp-edged delta wing of zero thickness, initially at zero angle of attack. The freestream Mach number and Reynolds number are 0.3 and 0.45 × 106, respectively. The governing equations are solved time-accurately using the implicit, upwind, Roe flux-difference splitting, finite-volume scheme. Both laminar and turbulent flow solutions are investigated. In the laminar flow solutions, validation of the computational results is carried …

Development And Application Of Adaptive Dynamic Grids For Wake Vortex/Ground Interaction, Ilker Emin Türkgeldi

Mechanical & Aerospace Engineering Theses & Dissertations

An adaptive and dynamic grid approach is developed for the numerical computations of wake vortex flow problems with ground interaction. The unnecessary grid points at the far field of the original, large, single zone grid are removed for computational efficiency. Next, the grid is modified into an adaptive one, where the fine core region keeps track of the vortices and can be split into two regions when the vortex separation distance exceeds a specified limit length. In the final step a multi zonal feature is added to this grid by means of two embedded grids placed at the vortex centers …

Ls-Dyna3d Modeling And Simulation For Uncontained Engine Debris Impact On Fuselage Skins, Robin Eileen Lawson

Mechanical & Aerospace Engineering Theses & Dissertations

Impact and penetration events for uncontained engine debris on fuselage skins are simulated using the LS-DYNA3D finite element analysis code. The LS-DYNA3D code is a nonlinear transient dynamic simulation tool with contact algorithms for impact. A finite element analysis is used to simulate the penetration of aluminum plates impacted by titanium impactors on aircraft-like skin panels. By gaining a more comprehensive understanding of this dynamic impact event, this work is meant to contribute to improving designs for damage tolerance and residual strength by providing modeling and analysis guidelines for the analyst.

Parametric studies are performed to determine the influence of …

A Five-Year Development Plan For The California Aviation Database, H.-S. Jacob Tsao

Faculty Publications

The California Aviation Database (CAvD) project was suggested by Caltrans Aeronautics Program to fulfill a need of the planners involved in aviation system planning and programming activities to locate and access aviation data and information in an efficient and comprehensive way. CAvD is being implemented in the form of an Internet website and is currently intended as a five-year project. However, the development can be accelerated, and the duration will depend on the available resources. CAvD is a joint project between the National Center of Excellence for Aviation Operations Research (NEXTOR) and the California Department of Transportation (Caltrans). Its primary …

Wind Tunnel Investigation Of Joined Wing Configurations, Jennifer Corneille

Theses and Dissertations

The Air Force Research Laboratory's Munitions Directorate is looking to extend the range of its small smart bomb. One proposed idea is to retrofit the bombs with a wing kit, particularly a joined wing configuration. A typical joined wing configuration is one where the wings are positioned in such a way that they form a diamond in both plan and front views. The purpose of this study is to conduct low speed wind tunnel testing of the joined wing configuration to help determine if the joined wing is more beneficial than a single wing configuration. Configurations with differing sweep angles …

Flow Separation Prevention On A Turbine Blade In Cascade At Low Reynolds Number, James P. Lake

Theses and Dissertations

The problem of flow separation from a low pressure turbine blade was investigated. The operating conditions under which the separation occurred were documented through measurement of surface pressure coefficients, boundary layer velocity and turbulence profiles, total pressure loss coefficient and wake velocity momentum deficit. Three different means for reducing the losses associated with the flow separation were also investigated. A boundary layer trip, dimples, and V-grooves were studied as passive means requiring no additional energy to reduce the separation losses. The boundary layer trip was only successful for an inlet and axial chord Reynolds number of 50k with a reduction …

Closely Supervised Reactive Control Of An Uninhabited Aerial Vehicle, Roy G. Glassco

Theses and Dissertations

Closely Supervised Reactive Control is an alternative control method for uninhabited aerial vehicles that incorporates some of the benefits of both manual and autonomous operations. Utilizing an onboard camera, an operator can control a UAV by manually choosing desired targets. The flight path of the uninhabited vehicle is determined autonomously from the camera gimbal angles. The operator of the payload (i.e. camera), has close supervision of the aircraft. The aircraft, using an onboard computer, is given autonomous control to alter flight path to fly towards a target and at a specified range, loiter over the target. In the basic mode …