Prevailing Torque Locking Feature Wear-Out,
2012
University of South Florida
Prevailing Torque Locking Feature Wear-Out, Adam Joseph Charles Zimandy
USF Tampa Graduate Theses and Dissertations
This thesis provides much needed representative sample data for reuse life of fully seated and torqued locknuts. Most national requirements for prevailing torque locking fasteners only specify unseated reuse life. This could create a potentially dangerous situation if unseated is misinterpreted for seated. This thesis provides comparative data for seated verses unseated configuration. Six aerospace, 3 all-metal and 3 nylon insert, and one non-aerospace locknuts were tested at preloads levels of unseated, 66%, 75%, and 85% of yield of bolt. The locknuts tested are MS21043-4, NAS1291-4, NAS1805-4, MS17825-4, MS21044D4, NAS1021N4, and Grade 8. A fixture was created in order to …
Use Of The Richtmyer-Meshkov Instability To Infer Yield Stress At High-Energy Densities,
2011
Los Alamos National Laboratory
Use Of The Richtmyer-Meshkov Instability To Infer Yield Stress At High-Energy Densities, Guy Dimonte, G. Terrones, F. J. Cherne, T. C. Germann, Virginie Dupont, K. Kadau, W. T. Buttler, D. M. Oro, C. Morris, D. L. Preston
Aerospace Engineering - Daytona Beach
We use the Richtmyer-Meshkov instability (RMI) at a metal-gas interface to infer the metal’s yield stress (Y) under shock loading and release. We first model how Y stabilizes the RMI using hydrodynamics simulations with a perfectly plastic constitutive relation for copper (Cu). The model is then tested with molecular dynamics (MD) of crystalline Cu by comparing the inferred Y from RMI simulations with direct stress-strain calculations, both with MD at the same conditions. Finally, new RMI experiments with solid Cu validate our simulation-based model and infer Y~0.47 GPa for a 36 GPa shock.
Link Performance Analysis For A Proposed Future Architecture Of The Air Force Satellite Control Network,
2011
Air Force Institute of Technology
Link Performance Analysis For A Proposed Future Architecture Of The Air Force Satellite Control Network, Eric W. Nelson
Theses and Dissertations
The Air Force Satellite Control Network (AFSCN) is a worldwide network of ground stations that support a wide variety of users from the National Aeronautics and Space Administration (NASA) to the National Reconnaissance Office (NRO). The network performs tracking, telemetry, and commanding (TT&C) for these varied users. Users, located at Satellite Operations Centers (SOC), must compete for time on the AFSCN. This thesis demonstrates how to predict satellite link performance, specifically by users of the AFSCN. It will also demonstrate how users might use this capability to save spacecraft power. A tool was created called the AFSCN Link Predictor (LP) …
Development Of Photographic Dynamic Measurements Applicable To Evaluation Of Flapping Wing Micro Air Vehicles,
2011
Air Force Institute of Technology
Development Of Photographic Dynamic Measurements Applicable To Evaluation Of Flapping Wing Micro Air Vehicles, Jeremy C. Murray
Theses and Dissertations
Developments in the area of flapping wing micro air vehicles (FWMAVs) of a small size and with limited range. This has lead to a great deal of interest in biomimetric designs based on flapping wing flyers, including the North American Hawkmoth (Manduca Sexta). By utilizing high speed photography and photogrammetry the dynamic flapping of the wing can be characterized for comparison with mathematical models, namely computational fluid dynamics (CFD) and finite element analysis (FEA).To successfully utilize high speed image capture, a method of successfully digitizing many data points in a short period of time needs to be developed. The effort …
Highly Sensitive Refractive Index Optical Fiber Sensors Fabricated By A Femtosecond Laser,
2011
Missouri University of Science and Technology
Highly Sensitive Refractive Index Optical Fiber Sensors Fabricated By A Femtosecond Laser, Jinpeng Yang, Lan Jiang, Sumei Wang, Qianghua Chen, Benye Li, Hai Xiao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Highly sensitive and robust refractive index (RI) fiber sensors are proposed, which are based on concatenating two micro air-cavities. the micro air-cavities embedded in the fiber along the core axis are fabricated by combining the techniques of femtosecond laser micromachining and arc fusion splicing. the full width at half-maximum (FWHM) of an attenuation peak of a sensor in air is 0.048 nm, and the extinction ratio is ∼15 dB. When the diameter of the cavity is slightly larger than the fiber core diameter, the sensor is highly sensitive to external RI changes. a high sensitivity of 172.4 nm/refractive index unit …
The Use Of Various Failure Criteria As Applied To High Speed Wear,
2011
Air Force Institute of Technology
The Use Of Various Failure Criteria As Applied To High Speed Wear, David A. Huber
Theses and Dissertations
This research has been aimed at developing methods to predict mechanical wear of sliding bodies at high velocities. Specifically, wear of test sled slippers at the Holloman High Speed Test Track at Holloman AFB, NM, is being considered. Developing a numerical model to represent the velocity range achieved at the test track is infeasible, so numerical modeling techniques must be adopted. Previous research has made use of finite element codes to simulate the high velocity sliding event. However, the extreme velocities at the test track can create numerical errors in the finite element codes. To avoid the numerical errors, an …
Scramjet Isolator Modeling And Control,
2011
Air Force Institute of Technology
Scramjet Isolator Modeling And Control, John R. Hutzel
Theses and Dissertations
The scramjet isolator is a duct in which pressure increases from the inlet to the combustor via a shock train. The shock train leading edge (LE) location must be controlled in an operational scramjet. A LE location measurement algorithm, dynamic model, and control algorithm were developed and validated with 500 frame per second (FPS) shadowgraph images in this research. The test apparatus consisted of a direct connect cold-flow high-speed wind tunnel with an adjustable ramp mounted in the tunnel floor. Ramp adjustments changed the tunnel cross-sectional area which changed the tunnel back pressure and LE location. Wall-mounted pressure transducers and …
Coupled Radiation-Gasdynamic Solution Method For Hypersonic Shock Layers In Thermochemical Nonequilibrium,
2011
Air Force Institute of Technology
Coupled Radiation-Gasdynamic Solution Method For Hypersonic Shock Layers In Thermochemical Nonequilibrium, Christopher L. Martin Jr.
Theses and Dissertations
The purpose of this research was to develop a highly accurate computational method for calculating the nonequilibrium radiative heat transfer within reentry shock layers. The nonequilibrium state of the flowfield was solved using the multispecies multitemperature nonequilibrium flow solver NH7AIR which is capable of separately tracking the vibrational energy of each diatomic species and the energy of the free electrons. The calculation of radiative heat transfer was performed by utilizing the detailed line-by-line spectral radiation solver SPRADIAN. Two radiative transport schemes were implemented in this coupled code. The first scheme was the standard tangent slab solution method. The second scheme …
Effect Of Thin Film Confined Between Two Dissimilar Solids On Interfacial Thermal Resistance,
2011
Missouri University of Science and Technology
Effect Of Thin Film Confined Between Two Dissimilar Solids On Interfacial Thermal Resistance, Zhi Liang, Hai-Lung Tsai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A Non-Equilibrium Molecular Dynamics Model is Developed to Investigate How a Thin Film Confined between Two Dissimilar Solids Affects the Thermal Transport Across the Material Interface. for Two Highly Dissimilar (Phonon Frequency Mismatched) Solids, It is Found that the Insertion of a Thin Film between Them Can Greatly Enhance Thermal Transport Across the Material Interface by a Factor of 2.3 If the Thin Film Has One of the Following Characteristics: (1)a Multi-Atom-Thick Thin Film of Which the Phonon Density of States (DOS) Bridges the Two Different Phonon DOSs for the Solid on Each Side of the Thin Film; (2)a Single-Atom-Thick …
Navigation And Position Determination With A Multicarrier Modulation Signal Of Opportunity,
2011
Air Force Institute of Technology
Navigation And Position Determination With A Multicarrier Modulation Signal Of Opportunity, Richard K. Martin, Jamie S. Velotta, John F. Raquet
AFIT Patents
A multicarrier modulation position determination method that includes deploying at least one known receiver with a known location and a second receiver with an unknown location. At least two signals of opportunity with different locations are obtained by both the receiver and the second receiver. The signals having a plurality of block data, the block data having block boundaries. The block boundaries including a beginning block boundary and an end block boundary. The block data further including a cyclic prefix at the beginning block boundary. Acquiring a plurality of data samples for at least a portion of the block data …
Wind Tunnel Modeling Of Small Electric Uav Power System Performance,
2011
California Polytechnic State University, San Luis Obispo
Wind Tunnel Modeling Of Small Electric Uav Power System Performance, Nathan R. Phelps
Aerospace Engineering
This report details the design and construction of a testing apparatus for characterization of small electric aircraft power systems designed for use in the California Polytechnic State University San Luis Obispo Aerospace Engineering department’s subsonic wind tunnel. This apparatus was constructed and implemented with the goal of determining system and component efficiencies of an entire power system using RC Aircraft components as an analog for systems currently in use in the current generation of small electric UAV’s in service with the US Armed Forces. The goal of these experiments was to determine where improvements in the system architecture can be …
Radiation In The Space Environment,
2011
California Polytechnic State University, San Luis Obispo
Radiation In The Space Environment, Sally Hermansen, Jennifer Shatts
Aerospace Engineering
No abstract provided.
Cubesat Constellation Analysis For Data Relaying,
2011
California Polytechnic State University, San Luis Obispo
Cubesat Constellation Analysis For Data Relaying, Bradley Ryan Smalarz
Master's Theses
Current CubeSat communication technology limits the amount of time, and number of accesses with ground stations. It has been proposed to use a constellation of CubeSats to improve relay performance and increase the number of accesses between a CubeSat and ground stations. By using the spatial and temporal analysis features of STK, coupled with the STK/Matlab interface a robust tool was created to analyze the performance of CubeSat constellations based on a store-and-forward communications model which is not currently supported by the STK Engine. Utilizing the Connect messaging format through a socket connection on the local machine, a Matlab graphical …
Experimental Investigation Of A 2-D Air Augmented Rocket: Effects Of Nozzle Lip Thickness On Rocket Mixing And Entrainment,
2011
California Polytechnic State University, San Luis Obispo
Experimental Investigation Of A 2-D Air Augmented Rocket: Effects Of Nozzle Lip Thickness On Rocket Mixing And Entrainment, Trevor Allen Montre
Master's Theses
Cold-flow tests were performed using a simulated Air Augmented Rocket (AAR) operating as a mixer-ejector in order to investigate the effects of varied primary nozzle lip thickness on mixing and entrainment. The simulated primary rocket ejector was supplied with nitrogen at a maximum chamber stagnation pressure of 1712 psi, and maximum flow rate of 1.67 lbm/s. Secondary air was entrained from a plenum, producing pressures as low as 6.8 psi and yielding maximum stagnation pressure ratios as high as 160. The primary ejector nozzles each had an area ratio of approximately 20, yielding average primary exit Mach numbers …
Global Optimization Of Mga-Dsm Problems Using The Interplanetary Gravity Assist Trajectory Optimizer (Igato),
2011
California Polytechnic State University, San Luis Obispo
Global Optimization Of Mga-Dsm Problems Using The Interplanetary Gravity Assist Trajectory Optimizer (Igato), Jason M. Bryan
Master's Theses
Interplanetary multiple gravity assist (MGA) trajectory optimization has long been a field of interest to space scientists and engineers. Gravity assist maneuvers alter a spacecraft's velocity vector and potentially allow spacecraft to achieve changes in velocity which would otherwise be unfeasible given our current technological limitations. Unfortunately, designing MGA trajectories is difficult and in order to find good solutions, deep space maneuvers (DSM) are often required which further increase the complexity of the problem. In addition, despite the active research in the field over the last 50 years, software for MGA trajectory optimization is scarce. A few good commercial, and …
Comet: Constrained Optimization Of Multiple-Dimensions For Efficient Trajectories,
2011
California Polytechnic State University, San Luis Obispo
Comet: Constrained Optimization Of Multiple-Dimensions For Efficient Trajectories, Michael Curt Conrad
Master's Theses
The paper describes the background and concepts behind a master’s thesis platform known as COMET (Constrained Optimization of Multiple-dimensions for Efficient Trajectories) created for mission designers to determine and evaluate suitable interplanetary trajectories. This includes an examination of the improvements to the global optimization algorithm, Differential Evolution, through a cascading search space pruning method and decomposition of optimization parameters. Results are compared to those produced by the European Space Agency’s Advanced Concept Team’s Multiple Gravity Assist Program. It was found that while discrepancies in the calculation of ΔV’s for flyby maneuvers exist between the two programs, COMET showed a noticeable …
Improving The Efficiency Of Lpg Compression Ignition Engines For Passenger Cars Through Waste Heat Recovery,
2011
Missouri University of Science and Technology
Improving The Efficiency Of Lpg Compression Ignition Engines For Passenger Cars Through Waste Heat Recovery, Alberto Boretti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The turbocharged direct injection lean burn Diesel engine is the most efficient now in production for transport applications with full load brake efficiencies up to 40 to 45% and reduced penalties in brake efficiencies reducing the load by the quantity of fuel injected. the secrets of this engine's performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. the major downfalls of this engine are the carbon dioxide emissions and the depletion of fossil fuels using fossil diesel, the energy security …
Alternative Crankshaft Mechanisms And Kinetic Energy Recovery Systems For Improved Fuel Economy Of Light Duty Vehicles,
2011
Missouri University of Science and Technology
Alternative Crankshaft Mechanisms And Kinetic Energy Recovery Systems For Improved Fuel Economy Of Light Duty Vehicles, Alberto Boretti, Houshsng Masudi, Joseph Scalzo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The introduction of advanced internal combustion engine mechanisms and powertrains may improve the fuel conversion efficiency of an engine and thus reduce the amount of energy needed to power the vehicle. the paper presents a novel design of a variable compression ratio advanced spark ignition engine that also permits an expansion ratio that may differ from the induction stroke therefore generating an Atkinson cycle effect. the stroke ratio and the ratio of maximum to minimum in-cylinder volumes may change with load and speed to provide the best fuel conversion efficiency. the variable ratio of maximum to minimum in-cylinder volumes also …
Efficient Uncertainty Quantification In Multidisciplinary Analysis Of A Reusable Launch Vehicle,
2011
Missouri University of Science and Technology
Efficient Uncertainty Quantification In Multidisciplinary Analysis Of A Reusable Launch Vehicle, Benjamin R. Bettis, Serhat Hosder, Tyler Winter
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The objective of this study was to apply a recently developed uncertainty quantification framework to the multidisciplinary analysis of a reusable launch vehicle (RLV). This particular framework is capable of efficiently propagating mixed (inherent and epistemic) uncertainties through complex simulation codes. the goal of the analysis was to quantify uncertainty in various output parameters obtained from the RLV analysis, including the maximum dynamic pressure, cross-range, range, and vehicle takeoff gross weight. Three main uncertainty sources were treated in the simulations: (1) reentry angle of attack (inherent uncertainty), (2) altitude of the initial reentry point (inherent uncertainty), and (3) the Young's …
Vortex Tilting And The Enhancement Of Spanwise Flow In Flapping Wing Flight,
2011
University of Central Florida
Vortex Tilting And The Enhancement Of Spanwise Flow In Flapping Wing Flight, Spencer Frank
HIM 1990-2015
In summary the tilting mechanism helps to explain the overall flow structure and the stability of the leading edge vortex.; The leading edge vortex has been identified as the most critical flow structure for producing lift in flapping wing flight. Its stability depends on the transport of the entrained vorticity into the wake via spanwise flow. This study proposes a hypothesis for the generation and enhancement of spanwise flow based on the chordwise vorticity that results from the tilting of the leading edge vortex and trailing edge vortex. We investigate this phenomenon using dynamically scaled robotic model wings. Two different …
