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Air Force Institute of Technology

Theses/Dissertations

2006

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Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington Dec 2006

Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington

Theses and Dissertations

This research outlines the development and simulation of a signal processing approach to real time wavefront curvature sensing in adaptive optics. The signal processing approach combines vectorized Charge Coupled Device (CCD) read out with a wavefront modal estimation technique. The wavefront sensing algorithm analyzes vector projections of image intensity data to provide an estimate of the wavefront phase as a combination of several low order Zernike polynomial modes. This wavefront sensor design expands on an existing idea for vector based tilt sensing by providing the ability to compensate for additional modes. Under the proposed wavefront sensing approach, the physical wavefront …

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Reconstructing Spectral Scenes Using Statistical Estimation To Enhance Space Situational Awareness, Travis F. Blake Dec 2006

Reconstructing Spectral Scenes Using Statistical Estimation To Enhance Space Situational Awareness, Travis F. Blake

Theses and Dissertations

A new sensor, the Advanced Electro-Optical System (AEOS) Spectral Imaging Sensor (ASIS) has been developed at the Maui Space Surveillance Complex (MSSC). ASIS is capable of collecting resolved imagery of space objects in 10's-100's of spectral bands while using an adaptive optics system. However, the stringent requirements of collecting ground-based images requires a sensor that induces spectral blurring. Post-processing algorithms to remove this blurring are required to fully exploit these spectral images. This research focuses on developing the reconstruction algorithms, based on proven estimation theories, required to spectrally deblur the images collected from ASIS. Additionally, the research will expand the …

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Branch Detonation Of A Pulse Detonation Engine With Flash Vaporized Jp-8, John David Slack Dec 2006

Branch Detonation Of A Pulse Detonation Engine With Flash Vaporized Jp-8, John David Slack

Theses and Dissertations

Pulse Detonation Engines (PDE) operating on liquid hydrocarbon fuels are limited to operating frequencies of 35 Hz due to long ignition times from a low energy ignition sources. This study shows ignition time of JP-8 can be nearly eliminated by igniting a thrust tube using a secondary detonation. A counter flow heat exchanger attached to a thrust tube utilized waste heat from the detonation process to heat JP-8 to supercritical conditions. The fuel flash vaporized when injected into the air stream of the engine. A detonation was produced by a spark in a 5 cm diameter, 1.37 m long tube. …

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Vacuum Chamber Construction And Contamination Study Of A Micro Pulsed Plasma Thruster, Jacob H. Debevec Dec 2006

Vacuum Chamber Construction And Contamination Study Of A Micro Pulsed Plasma Thruster, Jacob H. Debevec

Theses and Dissertations

The micro pulsed plasma thruster (micro-PPT) is a simple and versatile electric thruster capable of performing multiple missions, from precise attitude control on standard satellites to primary propulsion for nanosatellites. In order to fill this role as both industry and government move toward utilizing smaller satellites, micro-PPTs first need to be thoroughly tested on the ground. This study examines the deposition profile and rate of particle emission from the thruster so that satellite designers understand any potential contamination issues with sensitive instruments and solar panels. Employing a newly assembled vacuum chamber system, four tests were completed with the micro-PPTs, and …

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Robust Estimation Of Mahalanobis Distance In Hyperspectral Images, Eduardo C. Meidunas Dec 2006

Robust Estimation Of Mahalanobis Distance In Hyperspectral Images, Eduardo C. Meidunas

Theses and Dissertations

This dissertation develops new estimation methods that fit Johnson distributions and generalized Pareto distributions to hyperspectral Mahalanobis distances. The Johnson distribution fit is optimized using a new method which monitors the second derivative behavior of exceedance probability to mitigate potential outlier effects. This univariate distribution is then used to derive an elliptically contoured multivariate density model for the pixel data. The generalized Pareto distribution models are optimized by a new two-pass method that estimates the tail-index parameter. This method minimizes the mean squared fitting error by correcting parameter values using data distance information from an initial pass. A unique method …

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An Exploration Of Several Structural Measurement Techniques For Usage With Functionally Graded Materials, Robert A. Reuter Dec 2006

An Exploration Of Several Structural Measurement Techniques For Usage With Functionally Graded Materials, Robert A. Reuter

Theses and Dissertations

Titanium / titanium boride functionally graded 6"x 1"x1" beams were subjected to a four-point beam test in order to critique the value of several measurement techniques. Also, finite element analysis results were compared with experimental values and general observations about the experiment were recorded. Uniform 85% TiB /15% Ti and uniform commercially pure titanium specimens were also subjected to the same loading conditions as a control. Techniques used include digital image correlation, fiber optic strain gauging, strain gauging, and differential infrared thermography techniques. The strain data results were compared with one another and to linear finite element models. It was …

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Integrated Conceptual Design Of Joined-Wing Sensor Craft Using Response Surface Models, Josh E. Dittmar Dec 2006

Integrated Conceptual Design Of Joined-Wing Sensor Craft Using Response Surface Models, Josh E. Dittmar

Theses and Dissertations

A multidisciplinary conceptual design and analysis of Boeing's joined-wing SensorCraft has been conducted. This analysis was completed using geometrical optimization, aerodynamic analyses, and response surface methodology on a composite structural model. Phoenix Integration's Model Center was used to integrate the sizing and analysis codes found in Raymer's text, "Aircraft Design: A Conceptual Approach" as well as those from the NASA derived conceptual design tool AirCraft Synthesis (ACSYNT), and a modified Boeing Finite Element Model (FEM). This research demonstrated the utility of integrated low-order models for fast and inexpensive conceptual modeling of unconventional aircraft designs.

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Analysis Of Layered Social Networks, Jonathan T. Hamill Oct 2006

Analysis Of Layered Social Networks, Jonathan T. Hamill

Theses and Dissertations

Prevention of near-term terrorist attacks requires an understanding of current terrorist organizations to include their composition, the actors involved, and how they operate to achieve their objectives. To aid this understanding, operations research, sociological, and behavioral theory relevant to the study of social networks are applied, thereby providing theoretical foundations for new methodologies to analyze non-cooperative organizations, defined as those trying to hide their structure or are unwilling to provide information regarding their operations. Techniques applying information regarding multiple dimensions of interpersonal relationships, inferring from them the strengths of interpersonal ties, are explored. A layered network construct is offered that …

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Theory Of Effectiveness Measurement, Richard K. Bullock Sep 2006

Theory Of Effectiveness Measurement, Richard K. Bullock

Theses and Dissertations

Effectiveness measures provide decision makers feedback on the impact of deliberate actions and affect critical issues such as allocation of scarce resources, as well as whether to maintain or change existing strategy. Currently, however, there is no formal foundation for formulating effectiveness measures. This research presents a new framework for effectiveness measurement from both a theoretical and practical view. First, accepted effects-based principles, as well as fundamental measurement concepts are combined into a general, domain independent, effectiveness measurement methodology. This is accomplished by defining effectiveness measurement as the difference, or conceptual distance from a given system state to some reference …

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Investigating Barriers To Knowledge Management: A Case Study Of The Air Force Center Of Excellence For Knowledge Management, Edgar L. Myers Iv Sep 2006

Investigating Barriers To Knowledge Management: A Case Study Of The Air Force Center Of Excellence For Knowledge Management, Edgar L. Myers Iv

Theses and Dissertations

Knowledge is becoming recognized as an organization's most valuable and powerful resource. As a resource, knowledge is used to improve an organization's efficiency and effectiveness, to create innovative solutions, and to enhance decision making capabilities. Being such an important resource, it stands to reason that an organization's knowledge resources must be effectively managed. However, while an organization attempts to manage its knowledge, its efforts are constrained by a variety of influences acting as barriers. Using Holsapple and Joshi's (2000) "influences on the management of knowledge" framework, the purpose of this research is to identify those barriers which are acting as …

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An Adaptive Tabu Search Heuristic For The Location Routing Pickup And Delivery Problem With Time Windows With A Theater Distribution Application, Robert E. Burks Jr. Sep 2006

An Adaptive Tabu Search Heuristic For The Location Routing Pickup And Delivery Problem With Time Windows With A Theater Distribution Application, Robert E. Burks Jr.

Theses and Dissertations

The time constrained pickup and delivery problem (PDPTW) is a problem of finding a set of routes for a fleet of vehicles in order to satisfy a set of transportation requests. Each request represents a user-specified pickup and delivery location. The PDPTW may be used to model many problems in logistics and public transportation. The location routing problem (LRP) is an extension of the vehicle routing problem where the solution identifies the optimal location of the depots and provides the vehicle schedules and distribution routes. This dissertation seeks to blend the PDPTW and LRP areas of research and formulate a …

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Lightweight In-Plane Actuated Deformable Mirrors For Space Telescopes, Michael J. Shepherd Sep 2006

Lightweight In-Plane Actuated Deformable Mirrors For Space Telescopes, Michael J. Shepherd

Theses and Dissertations

This research focused on lightweight, in-plane actuated, deformable mirrors, with the ultimate goal of developing a 20- meter light gathering aperture for space telescopes. The 0.127 meter diameter deformable mirror small scale testbed was modelled infinite elements using MSC.Nastran software and then used as a basis for a quasi-static controller. Experimental tracking of Zernike tip, tilt, and defocus modes was accomplished. The analytical solutions to plate-membrane and beam-string ordinary differential equations were developed. A simplified approach to modelling the axisymmetric cases was also presented. A novel static control strategy, the Modal Transformation Method, was developed to form Zernike surfaces within …

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Dynamics And Control Of Tethered Satellite Formations For The Purpose Of Space-Based Remote Sensing, Kurt A. Vogel Sep 2006

Dynamics And Control Of Tethered Satellite Formations For The Purpose Of Space-Based Remote Sensing, Kurt A. Vogel

Theses and Dissertations

This dissertation assesses the utility of tethered satellite formations for the space-based remote sensing mission. Energy dissipation is found to have an adverse effect on foundational rigid body (Likins-Pringle) equilibria. It is shown that a continuously earth-facing equilibrium condition for a fixed-length tethered system does not exist since the spin rate required for the proper precession would not be high enough to maintain tether tension. The range of required spin rates for steady-spin motion is numerically defined here, but none of these conditions can meet the continuously earth-facing criteria. Of particular note is the discovery that applying certain rigid body …

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Statistical Approach To Background Subtraction For Production Of High-Quality Silhouettes For Human Gait Recognition, Jennifer J. Samler Sep 2006

Statistical Approach To Background Subtraction For Production Of High-Quality Silhouettes For Human Gait Recognition, Jennifer J. Samler

Theses and Dissertations

This thesis uses a background subtraction to produce high-quality silhouettes for use in human identification by human gait recognition, an identification method which does not require contact with an individual and which can be done from a distance. A statistical method which reduces the noise level is employed resulting in cleaner silhouettes which facilitate identification. The thesis starts with gathering video data of individuals walking normally across a background scene. From there the video is converted into a sequence of images that are stored as joint photographic experts group (jpeg) files. The background is subtracted from each image using a …

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Parameter Estimation Of A Tactical Missile Using Linear Regression, Kelly S. Powers Sep 2006

Parameter Estimation Of A Tactical Missile Using Linear Regression, Kelly S. Powers

Theses and Dissertations

This research presents the method of Linear Regression as a parameter identification method to determine the longitudinal dimensional stability derivatives of a tactical missile. Missile flight histories are characterized by rapid accelerations, rapidly changing mass property characteristics with often short flight times. These characteristics make accurate parameter estimation of the missile aerodynamics more challenging than for aircraft. The simulation used for this research was created in MATLAB/SIMULINK based on the missile trajectory program, TRAP. The aerodynamic data for the 6- DoF missile model was based on a supersonic, tail controlled missile similar to an AIM-9X missile. Two command input types …

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Development And Testing Of A High-Speed Real-Time Kinematic Precise Dgps Positioning System Between Two Aircraft, Christopher J. Spinelli Sep 2006

Development And Testing Of A High-Speed Real-Time Kinematic Precise Dgps Positioning System Between Two Aircraft, Christopher J. Spinelli

Theses and Dissertations

This research involves the design, implementation, and testing of a high-speed, real-time kinematic, precise differential GPS positioning system for use in airborne applications such as automated aerial-refueling and close formation flying. Although many of the current ambiguity resolution techniques use the residuals from the least squares position estimation to determine the true ambiguity set, this thesis presents a novel approach to the ambiguity resolution problem, called the minimum indicator. Instead of assuming the ambiguity set with the lowest residuals is the true set, other special characteristics of the residuals are examined. This increases the confidence that the algorithm has selected …

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Optimizing The Replication Of Multi-Quality Web Applications Using Aco And Wolf, Judson C. Dressler Sep 2006

Optimizing The Replication Of Multi-Quality Web Applications Using Aco And Wolf, Judson C. Dressler

Theses and Dissertations

This thesis presents the adaptation of Ant Colony Optimization to a new NP-hard problem involving the replication of multi-quality database-driven web applications (DAs) by a large application service provider (ASP). The ASP must assign DA replicas to its network of heterogeneous servers so that user demand is satisfied and replica update loads are minimized. The algorithm proposed, AntDA, for solving this problem is novel in several respects: ants traverse a bipartite graph in both directions as they construct solutions, pheromone is used for traversing from one side of the bipartite graph to the other and back again, heuristic edge values …

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An Investigation Of The Effects Of Boundary Avoidance On Pilot Tracking, Randy D. Warren Sep 2006

An Investigation Of The Effects Of Boundary Avoidance On Pilot Tracking, Randy D. Warren

Theses and Dissertations

Pilot-Involved Oscillations (PIOs) remain a significant issue in the design, testing and operations of aerospace vehicles. Traditional methods for predicting, describing, and analyzing these events have provided the community with improved methods for minimizing the occurrences of PIOs. However, these events continue to occur over a wide range of aerospace vehicle types and over a wide range of pilot acumen. The introduction of boundary avoidance tracking (BAT) by Mr. William Gray in 2004 added a missing piece to the PIO puzzle. This theory presented that PIOs may result from increasing pilot gain resulting not from maintaining a specified condition, but …

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Existence Of Large Solutions To Semilinear Elliptic Equations With Multiple Terms, David N. Smith Sep 2006

Existence Of Large Solutions To Semilinear Elliptic Equations With Multiple Terms, David N. Smith

Theses and Dissertations

We consider the semilinear elliptic equation Δu = p(x)uα + q(x)uβ on a domain Ω ⊆ Rn, n ≥ 3, where p and q are nonnegative continuous functions with the property that each of their zeroes is contained in a bounded domain Ωp or Ωq, respectively in Ω such that p is positive on the boundary of Ωp and q is positive on the boundary of Ωq. For Ω bounded, we show that there exists a nonnegative solution u such that u(x) → ∞ as x → ∂Ω if …

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Dual Fine Tracking Control Of A Satellite Laser Communication Uplink, Louis A. Noble Sep 2006

Dual Fine Tracking Control Of A Satellite Laser Communication Uplink, Louis A. Noble

Theses and Dissertations

A dual fine tracking control system (FTCS) is developed for a single aperture optical communication receiver to compensate for high frequency disturbances affecting tracking of two incident laser communication beams. The optical communication receiver resides within a payload module aboard a geosynchronous satellite, while each laser communication transmitter is housed within a module aboard a high altitude unmanned aerial vehicle (UAV). In addition to platform specific disturbances, the impact of atmospheric optical disturbances affecting tracking error are investigated. The system dynamics and FTCS are modeled and evaluated in MATLAB and SIMULINK. An optimal controller is developed to mitigate these disturbances …

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Scaling Flight Tests Of Unmanned Air Vehicles, Jeevani I. Abeygoonewardene Sep 2006

Scaling Flight Tests Of Unmanned Air Vehicles, Jeevani I. Abeygoonewardene

Theses and Dissertations

Increasing technological advances and research interest in unmanned air vehicles (UAVs), have led to the need for having safe, inexpensive and effective means of experimenting with their fight performance and surveillance capabilities. Work has previously been done in areas of controlling, analyzing, and predicting cooperative and autonomous operations of UAVs and other vehicles. In addition, there are well established guidelines for scaling experiments in fluid mechanics, where geometric, kinematic and dynamic similarity is obtained by formulating problems in terms of non dimensional variables using dimensional analysis. However, little or no work has been done in developing experiments or guidelines for …

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Effects Of Phase Difference Between Axial And Contact Loads On Fretting Fatigue Behavior Of Titanium Alloy, Mohammad Almajali Sep 2006

Effects Of Phase Difference Between Axial And Contact Loads On Fretting Fatigue Behavior Of Titanium Alloy, Mohammad Almajali

Theses and Dissertations

Fretting fatigue is the surface damage that occurs at the interface between two components that are undergoing a small amplitude oscillatory movements. It results in a reduction of the material life as compared to the plain fatigue. Most of the previous works were accomplished under a constant applied normal load and a little effort was done under a variable contact load, while none of these studies has considered the phase difference between the axial load and the contact load. The primary goal of this study is to investigate the effect of phase difference between axial and contact loads on fretting …

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Fault And Defect Tolerant Computer Architectures: Reliable Computing With Unreliable Devices, George R. Roelke Iv Sep 2006

Fault And Defect Tolerant Computer Architectures: Reliable Computing With Unreliable Devices, George R. Roelke Iv

Theses and Dissertations

This research addresses design of a reliable computer from unreliable device technologies. A system architecture is developed for a "fault and defect tolerant" (FDT) computer. Trade-offs between different techniques are studied and yield and hardware cost models are developed. Fault and defect tolerant designs are created for the processor and the cache memory. Simulation results for the content-addressable memory (CAM)-based cache show 90% yield with device failure probabilities of 3 x 10(-6), three orders of magnitude better than non fault tolerant caches of the same size. The entire processor achieves 70% yield with device failure probabilities exceeding 10(-6). The required …

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Factors And Interactions That Affect Air Force C-17 Aircraft Mission Capable Rates, Scotty A. Pendley Sep 2006

Factors And Interactions That Affect Air Force C-17 Aircraft Mission Capable Rates, Scotty A. Pendley

Theses and Dissertations

Given the high demand for mission capable airlift aircraft and considering increasing budget pressures, Air Mobility Command decision makers need a better understanding of mission capable (MC) rate-related factors and their interactions for mobility aircraft. This is needed to comprehend how issues such as airlift funding, current and future force reductions, and manning and experience levels may impact future MC rates for air mobility assets. Existing tools do not incorporate several key variables that the literature suggests are related to MC rates. Using a longitudinal approach, this thesis combines C-17 aircraft data with a structural equations modeling approach to evaluate …

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Navigation Using Signals Of Opportunity In The Am Transmission Band, Jonathan A. Mcellroy Sep 2006

Navigation Using Signals Of Opportunity In The Am Transmission Band, Jonathan A. Mcellroy

Theses and Dissertations

Maintaining a precision navigation solution both in a GPS hostile jamming environment and also in a GPS non-compatible terrain area is of great importance. To that end, this thesis evaluates the ability to navigate using signals from the AM band of the electromagnetic spectrum (520 to 1710 kHz). Navigation position estimates are done using multi-lateration techniques similar to GPS. However, pseudoranges are created using Time Difference of Arrival (TDOA) distances between a reference receiver and a mobile receiver, allowing the mobile receiver to obtain absolute position estimates over time. Four methods were developed for estimating the cross-correlation peak within a …

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Fast Scene Based Nonuniformity Correction With Minimal Temporal Latency, Christopher A. Rice Sep 2006

Fast Scene Based Nonuniformity Correction With Minimal Temporal Latency, Christopher A. Rice

Theses and Dissertations

The focus of this research was to derive a new algorithm for correction of gain nonuniformities in LIDAR focal plane arrays using as few frames as possible. Because of the current low production rate of LIDAR focal plane arrays there is a natural tendency for extreme nonuniformities to exist on a pixel by pixel basis as the manufacturing technique has not yet been perfected. Generally, nonuniformity correction techniques require a large number of frames and/or have obscure requirements on the translational shifts in the input image frames. This thesis presents a solution for finding multiplicative nonuniformities that exist in a …

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Laser Covariance Vibrometry For Unsymmetrical Mode Detection, Michael C. Kobold Sep 2006

Laser Covariance Vibrometry For Unsymmetrical Mode Detection, Michael C. Kobold

Theses and Dissertations

Simulated cross - spectral covariance (CSC) from optical return from simulated surface vibration indicates CW phase modulation may be an appropriate phenomenology for adequate classification of vehicles by structural mode. The nonlinear structural to optical relationship is close to unity, avoiding nulls and high values; optical return contains sufficient spectral ID information necessary for data clustering. The FE model has contact between the homogeneous rolled armor and vehicle hull, a simple multi - layer skin model typical of most vehicles. Most of the high frequency energy moved to lower frequencies. This nonlinearity segments contact vibration modes into two classes: symmetrical …

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Optimal Dynamic Soaring For Full Size Sailplanes, Randel J. Gordon Sep 2006

Optimal Dynamic Soaring For Full Size Sailplanes, Randel J. Gordon

Theses and Dissertations

Dynamic soaring is a unique flying technique designed to allow air vehicles to extract energy from horizontal wind shears. Dynamic soaring has been used by seabirds like the Albatross to fly hundreds of kilometers a day across the ocean. Small hobby radio controlled sailplanes have also used this technique to achieve sustained speeds of over 200 miles per hour from just a simple hand toss. Dynamic soaring, however, has never before been studied for use on full size aircraft. The primary goal of this research was to prove or disprove the viability of dynamic soaring for enhancing a full size …

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Effects Of Polishing Shot-Peened Surfaces On Fretting Fatigue Behavior Of Ti-6al-4v, Kasey S. Scheel Sep 2006

Effects Of Polishing Shot-Peened Surfaces On Fretting Fatigue Behavior Of Ti-6al-4v, Kasey S. Scheel

Theses and Dissertations

The research of this thesis was done to investigate the effects of polishing a shot-peened specimen of Ti-6Al-4V on the fretting fatigue life of that specimen. The shot-peening process, though one of the most beneficial techniques in prolonging fretting fatigue life, creates a textured surface that may lead to problems on the micro level. This research was done in an attempt to further improve the peening process by examining the effects of another surface treatment to be used in conjunction, surface polishing. The rough peened surface may contain abrupt changes in surface geometry that act as stress risers, which are …

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Natural Frequencies And Mode Shapes Of A Nonlinear, Uniform Cantilevered Beam, Daniel J. Marquez-Chisolm Sep 2006

Natural Frequencies And Mode Shapes Of A Nonlinear, Uniform Cantilevered Beam, Daniel J. Marquez-Chisolm

Theses and Dissertations

A series of experiments in 1975, referred to as the Princeton Beam Experiments, were performed to measure natural frequencies and create a nonlinear elastic deformation model to improve helicopter main beam designs. These experiments used a homogeneous 7075 aluminum beam and have been referenced as a baseline for the past thirty years to validate computer models and theories in an effort to build beams capable of withstanding aero-elastic, static, and dynamic loading. The purpose of this study is to measure the dynamic nonlinear bending and torsion response of a cantilever beam. The natural frequencies are measured in the flatwise and …

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