Engineering Commons^™

Early Damage State Criterion From A Fault-Seeded Helicopter Gear Using Acoustic Emission And Neural Networks, Rudy L. Baum

Doctoral Dissertations and Master's Theses

In response to five failures since 2008 of the tail gearbox of multiple models of Sikorsky's H-60 helicopter, acoustic emission (AE) data collected from a rotating gearbox test stand at the Naval Air Station in Patuxtent River, MD, was used to monitor the initiation and propagation of a flaw from an electro-discharge machined (EDM) notch seeded on the face of a gear tooth. A period of testing was considered which spanned ~300,000 seconds or ~83 hours and culminates to a damage state such that a flaw has initiated on both ends of the EDM notch. AE data was analyzed for …

Curvature Induced Phase Stability Of An Intensely Heated Liquid, Kiran Sasikumar, Zhi Liang, David G. Cahill, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We Use Non-Equilibrium Molecular Dynamics Simulations to Study the Heat Transfer Around Intensely Heated Solid Nanoparticles Immersed in a Model Lennard-Jones Fluid. We Focus Our Studies on the Role of the Nanoparticle Curvature on the Liquid Phase Stability under Steady-State Heating. for Small Nanoparticles We Observe a Stable Liquid Phase Near the Nanoparticle Surface, Which Can Be at a Temperature Well above the Boiling Point. Furthermore, for Particles with Radius Smaller Than a Critical Radius of 2 Nm We Do Not Observe Formation of Vapor Even above the Critical Temperature. Instead, We Report the Existence of a Stable Fluid Region …

Non-Linear Optimization Applied To Angle-Of-Arrival Satellite-Based Geolocation, Stephen D. Hartzell

Theses and Dissertations

Geolocation is a common application for satellite systems. This involves estimating an object's location (herein called the subject) based on noisy satellite data. Many geolocation methods exist; however, none are tailored specifically for the unique problems faced by satellite systems. Some satellites are so far from the subject being localized that by the time the satellite receives a signal from the subject it might have moved appreciably. Furthermore, some satellites or terrestrial sensors may be much closer to the subject than others. Therefore, sensors may need to be weighted based upon their distance to the subject being localized. In addition, …

The Prospect Of Responsive Spacecraft Using Aeroassisted, Trans-Atmospheric Maneuvers, Robert A. Bettinger

Theses and Dissertations

Comprised of exo- and trans-atmospheric trajectory segments, atmospheric re-entry represents a complex dynamical event which traditionally signals the mission end-of-life for low-Earth orbit spacecraft. Transcending this paradigm, atmospheric re-entry can be employed as a means of operational maneuver whereby aerodynamic forces can be exploited to create an aeroassisted maneuver. Utilizing a notional trans-atmospheric, lifting re-entry vehicle with L/D =6, the first phase of research demonstrates the terrestrial reachability potential for skip entry aeroassisted maneuvers. By overflying a geographically diverse set of ground targets, comparative analysis indicates a significant savings in delta V expenditure for skip entry compared with exo-atmospheric maneuvers. …

Minimization Of The Effects Of Secondary Reactions On Turbine Film Cooling In A Fuel Rich Environment, Andrew T. Shewhart

Theses and Dissertations

The demand for increased thrust, higher engine efficiency, and reduced fuel consumption has increased the turbine inlet temperature and pressure in modern gas turbine engines. The outcome of these higher temperatures and pressures is the potential for unconsumed radical species to enter the turbine. Because modern cooling schemes for turbine blades involve injecting cool, oxygen rich air adjacent to the surface, the potential for reaction with radicals in the mainstream flow and augmented heat transfer to the blade arises. This study evaluated various configurations of multiple cylindrical rows of cooling holes in terms of both heat release and effective downstream …

The Differential Vector Phase-Locked Loop For Global Navigation Satellite System Signal Tracking, James J. Brewer

Theses and Dissertations

A novel differential vector phase-locked loop (DVPLL) is derived that takes GNSS code-phase and carrier-phase measurements from a base station and uses them to maintain an integer ambiguity resolved quality solution directly in the vector tracking loop of a rover receiver. The only state variables estimated and used to create the replica code and carrier signals from the base station measurements are three position and two clock states for a static test. Closing the individual loops solely through the navigation filter makes this a pure vector method. For short baselines, where differential atmospheric errors are small, the DVPLL can be …

Side-Stepping The Politics: Cooperative Programs, James Marshall, Garry Schnelzer

Space Dynamics Laboratory Publications

SDL Presentation on International Cooperative Programs

A Novel Asymptotic Expansion Homogenization Analysis For 3-D Composite With Relieved Periodicity In The Thickness Direction, Muhammad Ridlo Erdata Nasution, Naoyuki Watanabe, Atsushi Kondo, Arief Yudhanto

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A new asymptotic expansion homogenization analysis is proposed to analyze 3-D composite in which thermomechanical and finite thickness effects are considered. Finite thickness effect is captured by relieving periodic boundary condition at the top and bottom of unit-cell surfaces. The mathematical treatment yields that only 2-D periodicity (i.e. in in-plane directions) is taken into account. A unit-cell representing the whole thickness of 3-D composite is built to facilitate the present method. The equivalent in-plane thermomechanical properties of 3-D orthogonal interlock composites are calculated by present method, and the results are compared with those obtained by standard homogenization method (with 3-D …

"Cap" Cornish, Indiana Pilot: Navigating The Century Of Flight, Ruth Ann Ingraham

Purdue University Press Books

Clarence "Cap" Cornish was an Indiana pilot whose life spanned all but five years of the Century of Flight. Born in Canada in 1898, Cornish grew up in Fort Wayne, Indiana. He began flying at the age of nineteen, piloting a "Jenny" aircraft during World War I, and continued to fly for the next seventy-eight years. In 1995, at the age of ninety-seven, he was recognized by Guinness World Records as the world's oldest actively flying pilot. The mid-1920s to the mid-1950s were Cornish's most active years in aviation. During that period, sod runways gave way to asphalt and concrete; …

Space Shuttle Case Studies: Challenger And Columbia, Scott L. Post

Publications

The two Space Shuttle tragedies, Challenger and Columbia, have led to many papers on case studies on engineering ethics. The Challenger disaster in particular is often discussed due to the infamous teleconference that took place the night before the launch in which some engineers tried to postpone the launch. However, the space shuttle program itself is worthy of study as it relates to the engineering design process, and the details of the Challenger and Columbia disasters are worthy of discussion as they relate to a variety of sub-disciplines, including material science, thermodynamics, fluid mechanics, and heat transfer. This paper summarizes …

Model-Based 3d Sar Reconstruction, Chad Knight, Jake Gunther, Todd Moon

Space Dynamics Laboratory Publications

Three dimensional scene reconstruction with synthetic aperture radar (SAR) is desirable for target recognition and improved scene interpretability. The vertical aperture, which is critical to reconstruct 3D SAR scenes, is almost always sparsely sampled due to practical limitations, which creates an underdetermined problem. This papers explores 3D scene reconstruction using a convex model-based approach. The approach developed is demonstrated on 3D scenes, but can be extended to SAR reconstruction of sparsely sampled signals in the spatial and, or, frequency domains. The model-based approach enables knowledge-aided image formation (KAIF) by incorporating spatial, aspect, and sparsity magnitude terms into the image reconstruction. …

Numerical Investigation Of Pyrolysis Gas Blowing Pattern And Thermal Response Using Orthotropic Charring Ablative Material, Haoyue Weng, Alexandre Martin

Mechanical Engineering Faculty Publications

An orthotropic material model is implemented in a three-dimensional material response code, and numerically studied for charring ablative material. Model comparison is performed using an iso-Q sample geometry. The comparison is presented using pyrolysis gas streamlines and time series of temperature at selected virtual thermocouples. Results show that orthotropic permeability affects both pyrolysis gas flow and thermal response, but orthotropic thermal conductivity essentially changes the thermal performance of the material. The effect of orthotropic properties may have practical use such that the material performance can be manipulated by altering the angle of orthotropic orientation.

Numerical Study Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Davuluri, Alexandre Martin

Mechanical Engineering Faculty Publications

The spallation phenomenon might affect the aerodynamic heating rates of re-entry vehicles. To investigate spallation effects, a code is developed to compute the dynamics of spalled particles. The code uses a finite-rate chemistry model to study the chemical interactions of the particles with the flow field. The spallation code is one-way coupled to a CFD solver that models the hypersonic flow field around an ablative sample. Spalled particles behavior is numerically studied for argon and air flow field. The chemistry model is compared with that of Park's model which complies with oxidation and sublimation and shows disagreement for nitridation.

Influence Of Grain Size And Widmanstätten Colonies On Variability Of Tensile Properties Of Forged Ti-6al-4v, Blake T. Gaspar

Master's Theses

When testing forgings for specifications, it was found that some parts did not meet the requirements for mechanical properties. This triggered an investigation into two of the parts from the lot that did not meet specification. The ultimate reason for failure was due to lower than necessary yield strength and ultimate tensile strength values, as well as unwanted variability between regions of the part. Therefore, samples of the regions were tensile tested to determine the differences that existed in yield strength, ultimate tensile strength, and elongation. After tensile testing, quantitative metallography and fractography were conducted to identify aspects of the …

An Investigation Into The Properties And Fabrication Methods Of Thermoplastic Composites, Ann E. Livingston-Peters

Master's Theses

As applications for thermoplastic composites increase, the understanding of their properties become more important. Fabrication methods for thermoplastic composites continually improve to match designs specifications. These advanced thermoplastics have begun to show an improvement in mechanical properties over those found in thermoset composites commonly used in industry. Polyaryletherketones (PEK) have high service temperatures, good mechanical properties, and improved processing capabilities compared to thermoplastics used in the past making them important to the aerospace industry. The wide range of types of PEK make them suitable for a variety of applications, but selection of specific chemistries, processing parameters, and composite stack-ups determine …

A Study On The Vibrational Performance Characteristics Of An E22 Isolator After Outgassing And Bake-Out, Alma Melendez

Master's Theses

The launch environment experiences many vibration, shock, and acoustic loads. A great concern is the high random vibration levels that can damage components and spacecraft structures, which can cause a mission failure. An effective method of reducing high frequency energy is using isolators. Overall, the need for vibration isolation has been increasing because there has been an increase in the use of mechanisms in which vibrations are prevalent. In addition, there has not been extensive research on the effects of isolators that are outgassed and cured. Therefore, it is important to investigate and understand the vibrational effects on isolators. It …

Localization And System Identification Of A Quadcopter Uav, Kenneth Befus

Masters Theses

The research conducted explores the comparison of several trilateration algorithms as they apply to the localization of a quadcopter micro air vehicle (MAV). A localization system is developed employing a network of combined ultrasonic/radio frequency sensors used to wirelessly provide range (distance) measurements defining the location of the quadcopter in 3-dimensional space. A Monte Carlo simulation is conducted using the extrinsic parameters of the localization system to evaluate the adequacy of each trilateration method as it applies to this specific quadcopter application. The optimal position calculation method is determined.

Furthermore, flight testing is performed in which real range measurement data …

Flight Testing Small Uavs For Aerodynamic Parameter Estimation, Adam Thomas Chase

Master's Theses

A flight data acquisition system was developed to aid unmanned vehicle designers in verifying the vehicle's design performance. The system is reconfigurable and allows the designer to choose the correct combination of complexity, risk, and cost for a given flight test. The designer can also reconfigure the system to meet packaging and integration requirements. System functionality, repeatbility, and accuracy was validated by collecting data during multiple flights of a radio-controlled aircraft. Future work includes sensor fusion, thrust prediction methods, stability and control derivative estimation, and growing Cal Poly's small-scale component aerodynamic database.

Reduced-Order Reference Models For Adaptive Control Of Space Structures, Alexander I. Scherling

Master's Theses

In addition to serving as a brief overview of aspects relevant to reduced-order modeling (in particular balanced-state and modal techniques) as applied to structural finite element models, this work produced tools for visualizing the relationship between the modes of a model and the states of its balanced representation.

Specifically, error contour and mean error plots were developed that provide a designer with frequency response information absent from a typical analysis of a balanced model via its Hankel singular values. The plots were then used to analyze the controllability and observability aspects of finite element models of an illustrative system from …

Lightweight Uav Launcher, Ben Miller, Christian Valoria, Corinne Warnock, Jake Coutlee

Mechanical Engineering

This report discusses the design, construction, and testing of a lightweight, portable UAV launcher. There is a current need for a small team of soldiers to launch a US Marine Tier II UAV in a remote location without transport. Research was conducted into existing UAV launcher designs and the pros and cons of each were recorded. This research served as a basis for concept generation during the initial design development stage. It was required that the design weigh less than 110 lbs, occupy a smaller volume than 48" x 24" 18" in its collapsed state, be portable by a single …

A Comparative Study Of The Low Speed Performance Of Two Fixed Planforms Versus A Variable Geometry Planform For A Supersonic Business Jet, Aaron C. Smelsky

Doctoral Dissertations and Master's Theses

A numerical investigation of the effects of high lift devices on the low-speed performance of a generic swept wing and a delta wing was conducted. The two fixed planforms were initially sized to achieve the same high speed performance as the baseline variable geometry wing. Following a review of high lift devices a detailed analysis of their use was conducted with the aid of vortex lattice method and empirical formulations. The slat and Fowler flap combination proved to be the best mechanical solution. In comparison with the initially sized delta planform, the final delta planform required a 26% increase in …

Modification Of The Cal Poly Spacecraft Simulator System For Robust Control Law Verification, Tomoyuki Kato

Master's Theses

The Cal Poly Spacecraft Dynamics Simulator, also known as the Pyramidal Reaction Wheel Platform (PRWP), is an air-bearing four reaction wheel spacecraft simulator designed to simulate the low-gravity, frictionless condition of the space environment and to test and validate spacecraft attitude control hardware and control laws through real-time motion tests. The PRWP system was modified to the new Mk.III configuration, which adopted the MATLAB xPC kernel for better real-time hardware control. Also the Litton LN-200 IMU was integrated onto the PRWP and replaced the previous attitude sensor. Through the comparison of various control laws through motion tests the Mk.III configuration …

Dual High-Voltage Power Supply For Use On Board A Cubesat, Nicholas Weiser

Master's Theses

Since their conception in 1999, CubeSats have come and gone a long way. The first few that went into space were more of a “proof of concept,” and were more focused on sending simple data and photographs back to Earth. Since then, vast improvements have been made by over 40 universities and private firms, and now CubeSats are beginning to look towards interplanetary travel. These small satellites could provide a cost effective means of exploring the galaxy, using off the shelf components and piggy-backing on other launch vehicles with more expensive payloads. However, CubeSats are traditionally launched into Low Earth …

Addition Of A Stanton Gauge To The Boundary Layer Data System, Brittany Reanne Kinkade

Master's Theses

The Stanton gauge technique provides an indirect method for measurement of skin friction on a smooth aerodynamic surface in which a pressure tap is available. This thesis presents the design and evaluation of a new type of skin friction measurement gauge based on the Stanton gauge concept but not requiring a surface pressure tap. This new skin friction measurement gauge, called a "Flow Tab", can therefore be used on an aerodynamic model or aircraft surface without alteration of the surface. The Flow Tab is thus particularly well-suited to use with Cal Poly's Boundary Layer Data System (BLDS), a small, self-contained …

Analysis Of Environmentally Friendly Marking Ink For Military Equipment And Electronics, Liang Li

Master's Theses

Recent advancements in corrosion-resistance coating technology has reduce the use of environmentally harmful compounds such as Hexavalent Chromium by replacing Hexavalent Chromium in primers and topcoat. However, marking inks were neglected in the process. Products such as Enthone 50 series are still widely used, which contain compounds such as lead, hexavalent chromium, bisphenol A (BPA), Cadmium Sulfide, and more. Excluding catalyst compositions in Enthone, the chemicals in the ink alone contained three reproductive toxicant and numerous carcinogens. Therefore, it was essential to search and validate the performance of potential marking ink that would meet the standards in military applications.

Eleven …

Making Every Gram Count - Big Measurements From Tiny Platforms, C. S. Fish, C. M. Swenson, S. Bailey, R. Bevilacqua, T. Neilsen, A. Marchant, C. Frazier, E. Stromberg, C. Weston, M. Jeppesen, J. Sojka

Space Dynamics Laboratory Publications

Significant advances in Earth, solar, and space physics over the next decades will originate from new, system-level observational techniques. The most promising technique to still be fully developed and exploited requires conducting multi-point or distributed constellation-based observations. This system-level observational approach is required to understand the “big picture” coupling between disparate regions such as the solar-wind, magnetosphere, ionosphere, upper atmosphere, land, and ocean. However, the costs to date of these and other similar proposed constellations have been prohibitive given the traditional “large satellite” architectures and the multiple launch vehicles required for implementing the constellations.

Financially sustainable development and deployment of …

Effect Of 406 Mhz Elts And Cospas-Sarsat Cessation Of 121.5 Mhz Elt Monitoring On Search And Rescue Duration For General Aviation Aircraft Accidents In The Contiguous United States, Ryan J. Wallace, Todd P. Hubbard

International Journal of Aviation, Aeronautics, and Aerospace

Emergency Locator Transmitters (ELTs) are credited with saving hundreds of lives every year in the United States. Following an aircraft accident, these devices transmit an emergency beacon signal to the COSPAS-SARSAT satellite network, directing search and rescue forces to the crash site. In recent years, this constellation has been plagued by ELT false alarms, propagating a technology transition to new 406 MHz ELT systems. In 2009, the group ceased monitoring of 121.5 MHz ELTs, degrading search and rescue capability for legacy ELTs. The Federal Communications Commission twice attempted to enact regulations to mandate industry-wide transition to 406 MHz ELTs, however, …

The Role Of Unmanned Aircraft Systems (Uas) In Disaster Response And Recovery Efforts: Historical, Current And Future, Dennis Vincenzi, David C. Ison, Brent A. Terwilliger

Publications

A wide range of legislation has been proposed or put into place that restricts the use of unmanned systems. These actions by legislators and regulators will stifle the growth of this technology and the associated surrounding industry. The largest obstacle to the proliferation of UAS in the U.S. is the FAA. The FAA has designated the location of six test sites that are anticipated to allow for less restrictive and formative research to assess the technologies that the FAA has claimed need to exist in order to integrate UAS into the NAS. Further complicating the adoption of UAS for beneficent …

Space Environment, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Space Environment" from May 12, 2014.

Context & Overview, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Context & Overview" from May 12, 2014.