Open Access. Powered by Scholars. Published by Universities.®

Aerospace Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

2007

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 61 - 90 of 202

Full-Text Articles in Aerospace Engineering

Catalytic Partial Oxidation Reforming Of Jp8 And S8, Thomas G. Howell Jun 2007

Catalytic Partial Oxidation Reforming Of Jp8 And S8, Thomas G. Howell

Theses and Dissertations

Catalytic partial oxidation (CPOX) reforming experiments were performed using a 10 kW Aspen Products Group, Inc. fuel processing prototype utilizing military logistic fuels JP8 and S8. S8 is a sulfur-free Fisher-Tropsch fuel, while JP8 is a multi-fuel blend, which could impact reforming efficiency, product distribution and byproduct production. Sulfur contained within the JP8 will adversely affect the product distribution; therefore, desulfurization beds, capable of removing up to 1000 ppm sulfur, were incorporated into the system. The catalyst used in the prototype is noble metal dispersed on cordierite monolith. The goal of this experiment was to evaluate the efficiency and product …

Go to article

Effect Of Prior Aging On Fatigue Behavior Of Im7/Bmi 5250-4 Composite At 191°C, Christine G. Ladrido Jun 2007

Effect Of Prior Aging On Fatigue Behavior Of Im7/Bmi 5250-4 Composite At 191°C, Christine G. Ladrido

Theses and Dissertations

IM7/BMI 5250-4 with carbon fiber orientations [± 45] and [0/90] were aged in air at 191 °C for up to 1000 hours. The weight loss was analyzed during the aging process. Tension to failure tests were performed on both the unaged and aged specimens to establish a baseline for the Ultimate Tensile Strengths and Young's Modulus. Tension-tension cyclic load fatigue testing was conducted on the specimen to determine the effect of prior aging on the fatigue response of the composite. Cyclic strain accumulation was not influenced by prior aging, but it was influenced by the stress levels applied. [± 45] …

Go to article

High Temperature Degradation Of 5250-4 Polymer Resin, Patrick E. Link Jun 2007

High Temperature Degradation Of 5250-4 Polymer Resin, Patrick E. Link

Theses and Dissertations

5250-4 bismaleimide resin is used in high performance polymer matrix composites with high temperature aeronautical applications. This thesis investigated the thermal and oxidative degradation of 5250-4 neat resin powder in argon, air, and oxygen environments. The powder was aged at 163 deg. C, 177 deg. C, and 190 deg. C in all environments for at least 250 hours. Isothermal thermo-gravimetric analysis demonstrated that weight loss was negligible for aging in the argon environment, indicating weight loss is the result of an oxidative process at these temperatures. The 5250-4 powder exhibited an initial period of weight gain before eventually losing weight …

Go to article

The Effects Of Environment On The Interlaminar Shear Performance Of An Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Patrick D. Laffey Jun 2007

The Effects Of Environment On The Interlaminar Shear Performance Of An Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Patrick D. Laffey

Theses and Dissertations

This research investigated the interlaminar shear performance of an oxide/oxide ceramic matrix composite consisting of Nextel™ 720 fibers in a high purity, porous alumina (Al2O3) matrix. The interlaminar shear performance was observed in both tension and compression of double notched specimens (DNS) at 1200 °C. Interlaminar shear creep behavior was examined in both laboratory air and in steam environment at 1200 °C. In air, the creep stress was -6.5 MPa. In steam creep stresses included -4.0, -5.0, and -6.5 MPa. Primary and secondary creep regimes were observed in all air creep tests and the creep test …

Go to article

Compressive Creep Behavior Of Nextel™ 720/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, Neil R. Szymczak Jun 2007

Compressive Creep Behavior Of Nextel™ 720/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, Neil R. Szymczak

Theses and Dissertations

The aerospace community continues to push the envelope in engineering aircraft that fly higher, faster, and safer while operating with a greater degree of efficiency. To meet these operational requirements innovative aerospace components must be designed to operate in aggressive environments. This research will investigate the ultimate compressive strength and the compressive creep behavior of NextelTM 720/Alumina ceramic matrix composite at 1200 °C in air and 100% steam environments. The effects of creep loading history on the tensile and compressive material behavior will also be examined. The primary strengths of the N720/A composite are its oxide/oxide composition which inherently …

Go to article

A Small-Scale 3d Imaging Platform For Algorithm Performance Evaluation, Steven A. James Jun 2007

A Small-Scale 3d Imaging Platform For Algorithm Performance Evaluation, Steven A. James

Theses and Dissertations

In recent years, world events have expedited the need for the design and application of rapidly deployable airborne surveillance systems in urban environments. Fast and effective use of the surveillance images requires accurate modeling of the terrain being surveyed. The process of accurately modeling buildings, landmarks, or other items of interest on the surface of the earth, within a short lead time, has proven to be a challenging task. One approach of high importance for countering this challenge and accurately reconstructing 3D objects is through the employment of airborne 3D image acquisition platforms. While developments in this arena have significantly …

Go to article

Effects Of Prior Aging At 191°C On Creep Response Of Im7/Bmi 5250-4, Robert A. Salvia Jun 2007

Effects Of Prior Aging At 191°C On Creep Response Of Im7/Bmi 5250-4, Robert A. Salvia

Theses and Dissertations

The creep behavior of IM7/BMI 5250-4 with fiber orientations of [± 45] and [0/90] that were aged in air at 191 °C for up to 1000 hours was evaluated. The total weight loss during the aging process was also evaluated. Weight loss due to aging was 0.64% for the [0/90] fiber orientation and 0.72% for the [± 45] fiber orientation. Tensile tests to failure were conducted to establish tensile properties. The [0/90] specimens have a much higher stiffness and Ultimate Tensile Strength (UTS) values than the [± 45] specimens. The tensile tests of the aged specimens revealed that the Ultimate …

Go to article

Critical Life Prediction Research On Boron-Enhanced Ti-6al-4v, Kevin A. Schwendiman Jun 2007

Critical Life Prediction Research On Boron-Enhanced Ti-6al-4v, Kevin A. Schwendiman

Theses and Dissertations

Research on boron-enhanced Ti-6-4 has demonstrated the following improvements to the Ti-6-4 alloy: up to 40% increase in ultimate tensile strength, up to 30% increase in modulus/stiffness, while maintaining greater than 10% ductility at RT conditions. The increased properties are attributed to small additions of boron (-or= wt%), which refine the microstructure and result in a small volume fraction (~6 vol%) of fine TiB whiskers. Previous research indicates potential for substantial improvements in fatigue, fatigue crack growth, and fracture toughness. However, uncertainty regarding these second-tier mechanical properties is currently limiting implementation of this class of titanium alloys. This study of …

Go to article

Effects Of Prior Aging On The Creep Response Of Carbon Fiber Reinforced Pmr-15 Neat Resin At 288°C In An Air Environment, Christopher A. Back Jun 2007

Effects Of Prior Aging On The Creep Response Of Carbon Fiber Reinforced Pmr-15 Neat Resin At 288°C In An Air Environment, Christopher A. Back

Theses and Dissertations

The mechanical response of carbon fiber reinforced PMR-15 neat resin with a ± 45 fiber orientation was investigated at 288 °C. Mechanical testing was performed on unaged specimens and specimens that were aged up to 1000 hours in an air environment. Tensile tests were performed to determine Young's modulus of elasticity and Ultimate Tensile Strength. Creep tests were performed at creep stress levels of 30 and 60 MPa. Creep periods of at least 25 h in duration were followed by recovery at zero stress. Duration of the recovery period was at least twice the time of the creep period. Oxidation …

Go to article

Damage Considerations Of A Flexible Micro Air Vehicle Wing Using 3-D Laser Vibrometry, Leo L. Mendoza Jr. Jun 2007

Damage Considerations Of A Flexible Micro Air Vehicle Wing Using 3-D Laser Vibrometry, Leo L. Mendoza Jr.

Theses and Dissertations

In recent years there has been a major push towards a new class of unmanned aerial vehicles: micro air vehicles. A great amount of research has been done towards the aerodynamics, aeroelasticity, construction, and flight characteristics of flexible wing micro air vehicles. However, there has not been much research done regarding possible structural deficiencies of a flexible micro air vehicle wing. The focus of this research is to evaluate the effects of damage on a flexible micro air vehicle wing, particularly its natural frequencies and mode shapes, using three dimensional laser vibrometry. The flexible micro air vehicle wing studied was …

Go to article

Automated Carrier Landing Of An Unmanned Combat Aerial Vehicle Using Dynamic Inversion, Nicholas A. Denison Jun 2007

Automated Carrier Landing Of An Unmanned Combat Aerial Vehicle Using Dynamic Inversion, Nicholas A. Denison

Theses and Dissertations

Dynamic Inversion (DI) is a powerful nonlinear control technique which has been applied to several modern flight control systems. This research utilized concepts of DI in order to develop a controller to land an Unmanned Combat Aerial Vehicle (UCAV) on an aircraft carrier. The Joint Unmanned Combat Air System (J-UCAS) Equivalent Model was used as the test aircraft. An inner-loop DI controller was developed to control the pitch, roll, and yaw rate dynamics of the aircraft, while an outer-loop DI controller was developed to provide flight path commands to the inner-loop. The controller design and simulation were conducted in the …

Go to article

Cfd Investigation Of Effect Of Depth To Diameter Ratio On Dimple Flow // Computational Fluid Dynamics Investigation Of Effect Of Depth To Diameter Ratio On Dimple Flow Dynamics, Robert B. Etter Jun 2007

Cfd Investigation Of Effect Of Depth To Diameter Ratio On Dimple Flow // Computational Fluid Dynamics Investigation Of Effect Of Depth To Diameter Ratio On Dimple Flow Dynamics, Robert B. Etter

Theses and Dissertations

This study aimed to further the understanding of laminar flow through a dimple with the goal of mitigating flow separation. Dimples of various depth to diameter ratios (0.05, 0.15) were examined for three different dimple diameters and chordwise locations, corresponding to diameter based (ReD) and chordwise location based (Rex) Reynolds number combinations of ReD 20500\Rex 5000, ReD 20500 Rex 77000, and ReD 9000 Rex 21000. For the last combination, a dimple of depth to diameter ratio of 0.25 was also examined. The dimples were placed in a flat plate located in a diverging channel causing an adverse pressure gradient encouraging …

Go to article

Process Improvements For The Ah-64 Tail Rotor Vibration Analysis, Mark C. Newkirk Jun 2007

Process Improvements For The Ah-64 Tail Rotor Vibration Analysis, Mark C. Newkirk

Theses and Dissertations

The Apache was the first helicopter of its kind to fly with the tail rotor blade offset by 55 degrees as opposed to the traditional 90 degrees. Current balancing methods approximate the rotor system as a traditional 4 bladed, same plane system with different weight sensitivity coefficients for each set of blades. The Apache tail rotor computer model was built using the Rotorcraft Comprehensive Analysis System (RCAS) program. The objective was not to develop solutions for the sensitivity coefficients, but to identify predictive trends that result from the tail rotor blade location. Currently, sensitivity coefficients applied to the adjustment algorithms …

Go to article

A Comparison Of Film Cooling Techniques In A High Speed, True Scale, Fully Cooled Turbine Vane Ring, Michael J. Umholtz Jun 2007

A Comparison Of Film Cooling Techniques In A High Speed, True Scale, Fully Cooled Turbine Vane Ring, Michael J. Umholtz

Theses and Dissertations

An effort was undertaken to understand the impact of different film cooling configurations in a true scale turbine vane for three proprietary airfoil designs. The measurements for this study were taken at the United States Air Force Turbine Research Facility (TRF). The TRF enabled heat transfer data to be obtained on full scale turbine hardware under realistic engine conditions. The surface heat flux of the turbine blades was analyzed using the impulse response method. The overall effectiveness was compared between airfoil types at 60% span over varying streamwise locations on both suction and pressure surfaces. Using an approximated massflow, a …

Go to article

Development And Testing Of The Rigidizable Inflatable Get-Away-Special Experiment, Brady D. O'Neal Jun 2007

Development And Testing Of The Rigidizable Inflatable Get-Away-Special Experiment, Brady D. O'Neal

Theses and Dissertations

The purpose of this research project is to develop the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX) from a computer-based model into a space-qualified prototype. Past research projects have developed RIGEX's command and control, structural analysis, and integration with the orbiter. This thesis details the organization, assembly, and test planning for the RIGEX protoflight model. Strict requirements imposed by the National Aeronautics and Space Administration (NASA) must be fulfilled for any payload to travel into space. Based on the requirements set forth by NASA documentation, this thesis establishes appropriate assembly procedures for the construction of a space payload. Detailed design changes are …

Go to article

The Aerodynamic Performance Of The Houck Configuration Flow Guides, Dermot N. Killian Ii Jun 2007

The Aerodynamic Performance Of The Houck Configuration Flow Guides, Dermot N. Killian Ii

Theses and Dissertations

In an effort to explore efficient wing designs for UAV's, the Air Force is investigating the patented Houck Aircraft Configuration, which is a joined-wing aircraft with curved flow guides of varying camber connecting the upper and lower wingtips. Models were drawn in three-dimensions using Solidworks® with upper and lower wings drawn as identical NACA 2412 airfoil sections for all models. A variety of airfoil sections between the upper and lower wingtips were drawn and rotated to achieve a combination of cant and angle of attack variation. Subsequently, a solid part was lofted through these sections and merged with the upper …

Go to article

Final Development, Testing, And Flight Preparation Of The Rigidizable Get-Away-Special Experiment (Rigex), Zachary R. Miller Jun 2007

Final Development, Testing, And Flight Preparation Of The Rigidizable Get-Away-Special Experiment (Rigex), Zachary R. Miller

Theses and Dissertations

The purpose of this research is to support the final development of the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX). The RIGEX program is an experimental initial step in developing large-scale rigidizable inflatable structures, which can be utilized in space applications. The primary intent of RIGEX is to verify and validate ground testing of inflation and rigidization methods for inflatable space structures against a zero-gravity space environment. This is performed by designing a Canister for All Payload Ejections (CAPE) experiment to collect data on space rigidized structures for validation of ground testing methods. The results presented in this thesis provide documentation needed …

Go to article

Efficiency And Pressure Loss Characteristics Of An Ultra-Compact Combustor With Bulk Swirl, James T. Radtke Jun 2007

Efficiency And Pressure Loss Characteristics Of An Ultra-Compact Combustor With Bulk Swirl, James T. Radtke

Theses and Dissertations

Research was conducted on a novel combustor design using a highly centrifugal loaded circumferential cavity to enhance flame speeds and lower mixing time to lower overall combustion time achieving improved efficiency and stability. This Ultra-Compact Combustor (UCC) is fed air with a bulk swirl, resembling gas leaving a compressor without the final set of compressor guide vanes to straighten the flow, at higher than normal Mach numbers for a combustor. The larger Mach numbers in the combustor do not cause a total pressure loss in excess of what Rayleigh theory would dictate for the given heat addition taking place within …

Go to article

Using Student Space Assets For Atmospheric Science Research, Robert J. Twiggs May 2007

Using Student Space Assets For Atmospheric Science Research, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Using Student Space Assets For Atmospheric Science Research" from May 17, 2007.

Go to article

The Emerging Small Satellite Industry And Opportunities For Education, Robert J. Twiggs May 2007

The Emerging Small Satellite Industry And Opportunities For Education, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "The Emerging Small Satellite Industry and Opportunities for Education" from May 3, 2007.

Go to article

Autonomous And Cooperative Multi-Uav Guidance In Adversarial Environment, Ugur Zengin May 2007

Autonomous And Cooperative Multi-Uav Guidance In Adversarial Environment, Ugur Zengin

Mechanical and Aerospace Engineering Dissertations - Archive

The research presented in this dissertation is aimed at developing rule-based autonomous and cooperative guidance strategies for UAVs to perform missions such as path planning, target tracking and rendezvous while reducing their risk/threat exposure level, and avoiding threats and/or obstacles by utilizing measurement information provided by sensors. First, a mathematical formulation is developed to represent the area of operation that contains various types of threats, obstacles, restricted areas, in a single framework. Once constructed, there will be no need to distinguish between adversaries as the framework already contains the information on what needs to be avoided and the level of …

Go to article

Design, Analysis And Development Of A Morphable Wing Structure For Unmanned Aerial Vehicle Performance Augmentation, Abhijit Hiraman Supekar May 2007

Design, Analysis And Development Of A Morphable Wing Structure For Unmanned Aerial Vehicle Performance Augmentation, Abhijit Hiraman Supekar

Mechanical and Aerospace Engineering Theses - Archive

In this research, we propose mechanisms to continuously morph a wing from a lower aspect ratio to a higher and to further extremities of a gull and an inverted-gull configuration. The mechanism comprises of a linear actuator for the extension of the wing and the servo motors to obtain the gull and inverted gull configurations. The initial design and preliminary finite element representation using 3D-beams and plates in ANSYS Classic were the benchmarks to proceed for the detailed structural analysis of the complete wing in ANSYS Workbench. An elliptical pressure distribution at the quarter cord is assumed for the linear …

Go to article

Design And Implementation Of A Feedback Linearizing Controller And Kalman Filter For A Magnetic Levitation System, John Andrew Henley May 2007

Design And Implementation Of A Feedback Linearizing Controller And Kalman Filter For A Magnetic Levitation System, John Andrew Henley

Mechanical and Aerospace Engineering Theses - Archive

The principal investigation undertaken in this research is the development and subsequent implementation of a feedback linearizing nonlinear controller and extended Kalman filter for a laboratory-based Magnetic Levitation (Maglev) device. The Maglev hardware is both highly nonlinear and open-loop unstable in its dynamic response. The control and estimation scheme proposed in this work is first validated using an increasingly sophisticated level of simulations. The control and estimation algorithm had the sensor noise identified using hardware data. Then, the plant noise covariance is tuned using both on-line and off-line hardware data. Additionally, the output of the nonlinear controller is then mapped …

Go to article

A Generic Stability And Control Tool For Flight Vehicle Conceptual Design: Aeromech Software Development, Gary John Coleman May 2007

A Generic Stability And Control Tool For Flight Vehicle Conceptual Design: Aeromech Software Development, Gary John Coleman

Mechanical and Aerospace Engineering Theses - Archive

During the conceptual design (CD) phase, various solution concepts must, and should, be explored to select the best flight vehicle size and configuration in order to meet the mission requirements. As the aerospace industry advances novel aerospace flight vehicle configurations promising larger operational performance and overall efficiency, demanding integrated flight vehicles like the flying wing configuration (FWC) or blending wing body (BWB) are under investigation. Some of these novel configurations rely on novel control effectors (CE) and complex flight control systems in order to obtain the desired performance objectives. Clearly, stability and control plays an important roll in the design …

Go to article

An Evaluation Of Using Component Mode Synthesis For Structural Models, Richard Lynn Scott May 2007

An Evaluation Of Using Component Mode Synthesis For Structural Models, Richard Lynn Scott

Mechanical and Aerospace Engineering Theses - Archive

Structural analysts have used component mode synthesis (CMS), also known as substructuring, for decades to divide large structural models into smaller, more manageable models, and to reduce the size of the associated mathematical problem. Applying CMS can also reduce the front-end effort to build models, even models that are smaller than those for which CMS has typically been applied. This paper presents an evaluation of the accuracy of two smaller substructured models so that analysts might feel confident in applying CMS to gain the benefits. The evaluation starts with an introduction to CMS. Then, CMS is applied to a small, …

Go to article

Control And Simulation Of Relative Motion For Aerial Refueling In Racetrack Maneuver, Eunyoung Kim May 2007

Control And Simulation Of Relative Motion For Aerial Refueling In Racetrack Maneuver, Eunyoung Kim

Mechanical and Aerospace Engineering Theses - Archive

This thesis addresses the problem of controlling the receiver aircraft to achieve a successful aerial refueling. For the performance verification of the controller, a new set of nonlinear, 6-DOF, rigid body equations of motion for the receiver aircraft has been used. The equations are written in terms of state variables that are relative to the reference frame that is attached to, translates and rotates with the tanker aircraft. Furthermore, the nonlinear equations contain the wind effect terms and their time derivatives to represent the aerodynamic coupling involved between the two aircraft. These wind terms are obtained using an averaging technique …

Go to article

Optimization Of Zero Net-Mass Flow Actuators For Aero-Optics Applications, Moira L. Denatale, Jonathan M. Mihaly May 2007

Optimization Of Zero Net-Mass Flow Actuators For Aero-Optics Applications, Moira L. Denatale, Jonathan M. Mihaly

Renée Crown University Honors Thesis Projects - All

Using experimental methods, zero net-mass flow actuators were optimized to manipulate flow around an airborne laser turret in order to reduce destructive aero-optics effects. Synthetic jets are created by 50 mm and 27 mm piezoelectric disk actuators. Our optimization process involved identifying an actuator’s cavity size, driving frequency, and amplitude to achieve the strongest, most consistent jet possible. The effects of driving a single actuator versus driving two actuators in or out of phase with one another were also investigated. An initial cavity depth was determined using the Helmholtz resonator cavity approximation which estimates the ideal cavity depth for a …

Go to article

A Novel Cylindrical Punch Method To Characterize Interfacial Adhesion And Residual Stress Of A Thin Polymer Film, Bing Feng Ju, Kuo Kang Liu, Ming Fung Wong, Kai Tak Wan May 2007

A Novel Cylindrical Punch Method To Characterize Interfacial Adhesion And Residual Stress Of A Thin Polymer Film, Bing Feng Ju, Kuo Kang Liu, Ming Fung Wong, Kai Tak Wan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Adhesion of a pre-stressed silicone rubber film to a planar graphite surface was investigated by a new cylindrical punch method. a homemade apparatus was constructed to meet force and displacement resolutions of 0.1 μN and 10 nm. When the punch approached the intersurface force range across the punch-film gap, the film jumped into contact at "pull-in". Upon unloading, once the tensile load reached a threshold, a spontaneous delamination occurred at "pull-off" with a non-zero contact circle. a theoretical model was constructed based a simple energy balance. the new method can be used to characterize an adhesion interface between a pre-stressed …

Go to article

Optimization Of Zero Net-Mass Flow Actuators For Aero-Optics Applications, Moira L. Denatale, Jonathan M. Mihaly May 2007

Optimization Of Zero Net-Mass Flow Actuators For Aero-Optics Applications, Moira L. Denatale, Jonathan M. Mihaly

Renée Crown University Honors Thesis Projects - All

Using experimental methods, zero net-mass flow actuators were optimized to manipulate flow around an airborne laser turret in order to reduce destructive aero-optics effects. Synthetic jets are created by 50 mm and 27 mm piezoelectric disk actuators. Our optimization process involved identifying an actuator’s cavity size, driving frequency, and amplitude to achieve the strongest, most consistent jet possible. The effects of driving a single actuator versus driving two actuators in or out of phase with one another were also investigated. An initial cavity depth was determined using the Helmholtz resonator cavity approximation which estimates the ideal cavity depth for a …

Go to article

Analysis Of Tapered Laminated Composite Tubes Under Tension And Torsion, Chethana Shankara Rao May 2007

Analysis Of Tapered Laminated Composite Tubes Under Tension And Torsion, Chethana Shankara Rao

Mechanical and Aerospace Engineering Theses - Archive

Closed form expressions for determining the displacement and twisting angle of tapered composite tubes are developed. The analytical expressions are developed based on the modified laminated plate theory which includes the tubular wall curvature of the laminate. It is found that the axial deformation and the twisting angle calculated by the current method agree well with the results obtained from the finite element method. The effect of stacking sequence, taper angle and fiber orientations on the axial deformation and twisting angle are studied by using the developed method. It is found that the taper angle plays a significant role on …

Go to article

First Prev Next Last