Matching Items (39)

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Optimal Modeling of Knots in Wood

Description

A model has been developed to modify Euler-Bernoulli beam theory for wooden beams, using visible properties of wood knot-defects. Treating knots in a beam as a system of two ellipses

A model has been developed to modify Euler-Bernoulli beam theory for wooden beams, using visible properties of wood knot-defects. Treating knots in a beam as a system of two ellipses that change the local bending stiffness has been shown to improve the fit of a theoretical beam displacement function to edge-line deflection data extracted from digital imagery of experimentally loaded beams. In addition, an Ellipse Logistic Model (ELM) has been proposed, using L1-regularized logistic regression, to predict the impact of a knot on the displacement of a beam. By classifying a knot as severely positive or negative, vs. mildly positive or negative, ELM can classify knots that lead to large changes to beam deflection, while not over-emphasizing knots that may not be a problem. Using ELM with a regression-fit Young's Modulus on three-point bending of Douglass Fir, it is possible estimate the effects a knot will have on the shape of the resulting displacement curve.

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Created

Date Created
  • 2015-05

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Automatic Area Ruling of Aircraft Geometries

Description

This paper describes an aircraft design optimization tool for wave drag reduction. The tool synthesizes an aircraft wing and fuselage geometry using the Rhinoceros CAD program. It then implements an

This paper describes an aircraft design optimization tool for wave drag reduction. The tool synthesizes an aircraft wing and fuselage geometry using the Rhinoceros CAD program. It then implements an algorithm to perform area-ruling on the fuselage. The algorithm adjusts the cross-sectional area along the length of the fuselage, with the wing geometry fixed, to match a Sears-Haack distribution. Following the optimization of the area, the tool collects geometric data for analysis using legacy performance tools. This analysis revealed that performing the optimization yielded an average reduction in wave drag of 25% across a variety of Mach numbers on two different starting geometries. The goal of this project is to integrate this optimization tool into a larger trade study tool as it will allow for higher fidelity modeling as well as large improvements in transonic and supersonic drag performance.

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Created

Date Created
  • 2016-12

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Leading Edge Geometry Effects on Pressure Drag and Pressure Thrust for Various Wing Geometries

Description

The purpose of this paper is to discover what geometric characteristics of a wing and airfoil help to maximize leading edge suction through experimental testing. Three different stages of testing

The purpose of this paper is to discover what geometric characteristics of a wing and airfoil help to maximize leading edge suction through experimental testing. Three different stages of testing were conducted: a Proof of Concept, a Primary Experiment, and a Secondary Experiment. The Proof of Concept shows the effects of leading edge suction and the benefits it can posses. The Primary Experiment provided inconclusive data due to inaccuracies in the equipment. As a result, the Secondary Experiment was conducted in order to reduce the error effect as much as possible on the data. Unfortunately the Secondary Experiment provided inaccurate data as well. However, this paper does provide enough evidence to begin to question some of the long held beliefs regarding theoretical induced drag and whether it is true under all circumstances, or if it is only a good approximation for airfoils with full leading-edge suction effects.

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Created

Date Created
  • 2017-05

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Planing and The Effect of Bicycle Frame Stiffness on Rider Performance

Description

It is a common assumption in the bicycle industry that stiffer frames generally perform better than flexible frames, because they transfer power more efficiently and absorb less energy from the

It is a common assumption in the bicycle industry that stiffer frames generally perform better than flexible frames, because they transfer power more efficiently and absorb less energy from the rider's pedal stroke in the form of spring potential energy. However, in the last few years, Jan Heine of Bicycle Quarterly has developed an alternative theory, which he calls "planing", whereby a flexible frame can improve rider performance by not resisting the leg muscles as much, preventing premature muscle fatigue and allowing the rider to actually produce more consistent power, an effect which overwhelms any difference in power transfer between the different stiffness levels of frames. I performed several tests in which I measured the power input to the bicycle through the crankset and power output through a power-measuring trainer in the place of the rear hub. Heart rate data was collected along with most of these tests. Four bicycles were used with three distinct levels of stiffness. After performing several ANOVA tests to determine the effect of stiffness on the parameters of average power output during a sprint, maximum power output during a sprint, maximum heart rate during a sprint, difference between power-in and power-out during both sprints and longer efforts, and power quotient during a sprint, I found no effects of frame stiffness on any of these factors except power quotient. The finding for power quotient suggests a positive relationship between quotient and stiffness, which directly refutes the Planing Theory for the test riders and levels of stiffness represented in this test. Also, no statistically significant effect of stiffness on the difference between power-in and power-out was found, refuting the Power Transfer Theory for the riders and levels of stiffness represented in this test.

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Created

Date Created
  • 2016-12

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An Experimental Study of the Effect of Induction and Exhaust Systems on a Vehicle's Fuel Efficiency

Description

This thesis focuses on the effects of an engine's induction and exhaust systems on vehicle fuel efficiency, along with the challenges accompanying improvement of this parameter. The aim of the

This thesis focuses on the effects of an engine's induction and exhaust systems on vehicle fuel efficiency, along with the challenges accompanying improvement of this parameter. The aim of the project was to take an unconventional approach by investigating potential methods of increasing fuel economy via change of these systems outside the engine, as finding substantial gains via this method negates the need to alter engine architectures, potentially saving manufacturers research and development costs. The ultimate goal was to determine the feasibility of modifying induction and exhaust systems to increase fuel efficiency via reduction of engine pumping losses and increase in volumetric efficiency, with the hope that this research can aid others researching engine design in both educational and commercial settings. The first step toward achieving this goal was purchasing a test vehicle and performing experimental fuel efficiency testing on the unmodified, properly serviced specimen. A test route was devised to provide for a well-rounded fuel efficiency measurement for each trial. After stock vehicle trials were completed, the vehicle was to be taken out of service for a turbocharger system installation; unfortunately, challenges arose that could not be rectified within the project timeframe, and this portion of the project was aborted, to be investigated in the future. This decision was made after numerous fitment and construction issues with prefabricated turbo conversion parts were found, including induction and exhaust pipe size problems and misalignments, kit component packaging issues such as intercooler dimensions being too large, as well as manufacturing oversights, like failure to machine flanges flat for sealing and specification of incorrect flange sizes for mating components. After returning the vehicle to stock condition by removing the partially installed turbocharger system, the next step in the project was then installation of high-flow induction and exhaust systems on the test vehicle, followed by fuel efficiency testing using the same procedure as during the first portion of the experiment. After analysis of the quantitative and qualitative data collected during this thesis project, several conclusions were made. First, the replacement of stock intake and exhaust systems with high-flow variants did make for a statistically significant increase in fuel efficiency, ranging between 10 and 20 percent on a 95% confidence interval. Average fuel efficiency of the test vehicle rose from 21.66 to 24.90 MPG, an impressive increase considering the relative simplicity of the modifications. The tradeoff made was in noise produced by the vehicle; while the high-flow induction system only resulted in increased noise under very high-load circumstances, the high-flow exhaust system created additional noise under numerous load conditions, limiting the market applicability for this system. The most ideal vehicle type for this type of setup is sports/enthusiast cars, as increased noise is often considered a desirable addition to the driving experience; light trucks also represent an excellent application opportunity for these systems, as noise is not a primary concern in production of these vehicles. Finally, it was found that investing in high-flow induction and exhaust systems may not be a wise investment at the consumer level due to the lengthy payoff period, but for manufacturers, these systems represent a lucrative opportunity to increase fuel efficiency, potentially boosting sales and profits, as well as allowing the company to more easily meet federal CAFE standards in America. After completion of this project, there are several further research directions that could be taken to expand upon what was learned. The fuel efficiency improvements realized by installing high-flow induction and exhaust systems together on a vehicle were experimentally measured during testing; determining the individual effects of each of these systems installed on a vehicle would be the next logical research step within the same vein. Noise, vibration, and harshness increases after installing these systems were also noticed during experimental trials, so another future research direction could be an investigation into reducing these unwanted effects of high-flow systems. Finally, turbocharging to increase a vehicle's fuel efficiency, the original topic of this thesis, is another very important, contemporary issue in the world of improving vehicle fuel efficiency, and with manufacturers consistently moving toward turbocharged platform development, is a prime research topic in this area of study. In conclusion, the results from this thesis project exhibit that high-flow induction and exhaust systems can substantially improve a vehicle's fuel efficiency without modifying any internal engine components. This idea of improving a vehicle's fuel economy from outside the engine will ideally be further researched, such as by investigating turbocharger systems and their ability to improve fuel efficiency, as well as be developed and implemented by others in their educational projects and commercial products.

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Created

Date Created
  • 2016-12

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Investigation into the von Karman Vortex Street and the Relationship Between Reynolds and Strouhal Numbers

Description

This experiment used hotwire anemometry to examine the von Kármán vortex street and how different surface conditions affect the wake profile of circular airfoils, or bluff bodies. Specifically, this experiment

This experiment used hotwire anemometry to examine the von Kármán vortex street and how different surface conditions affect the wake profile of circular airfoils, or bluff bodies. Specifically, this experiment investigated how the various surface conditions affected the shedding frequency and Strouhal Number of the vortex street as Reynolds Number is increased. The cylinders tested varied diameter, surface finish, and wire wrapping. Larger diameters corresponded with lower shedding frequencies, rougher surfaces decreased Strouhal Number, and the addition of thick wires to the surface of the cylinder completely disrupted the vortex shedding to the point where there was almost no dominant shedding frequency. For the smallest diameter cylinder tested, secondary dominant frequencies were observed, suggesting harmonics.

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Created

Date Created
  • 2017-05

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Ionic Wind Propulsion

Description

This paper describes the research done to attempt to scale up thrusts produced by ionic wind thrusters, or "lifters" to magnitudes needed to power a 2 kg hobbyist remote-control airplane.

This paper describes the research done to attempt to scale up thrusts produced by ionic wind thrusters, or "lifters" to magnitudes needed to power a 2 kg hobbyist remote-control airplane. It includes background information on the Biefeld-Brown effect and the thrust it produces, an experiment that attempted to prove that thrust can be scaled up from smaller ionic wind thrusters to larger scales, and two models predicting thruster geometries and power sources needed to reach these thrusts. An ionic wind thruster could not be created that would power the hobbyist remote as a high-voltage power source with voltage and power high enough could not be obtained. Thrusters were created for the experiment using balsa wood, aluminum foil, and thin copper wire, and were powered using a 30 kV transformer. The thrusters attempted to test for correlations between thrust, electrode length, and current; electric field strength, and thrust; and thrust optimization through opening up air flow through the collector electrode. The experiment was inconclusive as all the thrusters failed to produce measurable thrust. Further experimentation suggests the chief failure mode is likely conduction from the collector electrode to the nearby large conductive surface of the scale.

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Created

Date Created
  • 2017-12

Dyanmics of Oversteer: Modelling Drift by Solving a System of Equations

Description

The dynamics of friction as they relate to automobile behavior have been heavily analyzed under conditions that are favorable and predictable in the realm of daily driving. The scope of

The dynamics of friction as they relate to automobile behavior have been heavily analyzed under conditions that are favorable and predictable in the realm of daily driving. The scope of this project is to investigate behavior of slip in unfavorable conditions and develop a mathematical solution that allows users to predict behavior of oversteer and excessive sideslip. I am fascinated by the topic as I have developed a background in the sport of drifting (controlled oversteer) and would like to contribute to the understanding of this lesser appreciated science. Highly valued components of the project such as velocities, forces, coefficients of friction, steering angles, slip angles, and multi-wheel analysis will all lead to a deeper understanding of relationships between aspects of a vehicle undergoing oversteer.

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Created

Date Created
  • 2020-05

DYNAMICS OF OVERSTEER: MODELLING DRIFT BY SOLVING A SYSTEM OF EQUATIONS

Description

The dynamics of friction as they relate to automobile behavior have been heavily analyzed under conditions that are favorable and predictable in the realm of daily driving. The scope of

The dynamics of friction as they relate to automobile behavior have been heavily analyzed under conditions that are favorable and predictable in the realm of daily driving. The scope of this project is to investigate behavior of slip in unfavorable conditions and develop a mathematical solution that allows users to predict behavior of oversteer and excessive sideslip. I am fascinated by the topic as I have developed a background in the sport of drifting (controlled oversteer) and would like to contribute to the understanding of this lesser appreciated science. Highly valued components of the project such as velocities, forces, coefficients of friction, steering angles, slip angles, and multi-wheel analysis will all lead to a deeper understanding of relationships between aspects of a vehicle undergoing oversteer.

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Agent

Created

Date Created
  • 2020-12

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Modeling Trajectories of Supersonic Projectiles

Description

The goal of this thesis project was to build an understanding of supersonic projectile dynamics through the creation of a trajectory model that incorporates several different aerodynamic concepts and builds

The goal of this thesis project was to build an understanding of supersonic projectile dynamics through the creation of a trajectory model that incorporates several different aerodynamic concepts and builds a criteria for the stability of a projectile. This was done iteratively where the model was built from a foundation of kinematics with various aerodynamic principles being added incrementally. The primary aerodynamic principle that influenced the trajectory of the projectile was in the coefficient of drag. The drag coefficient was split into three primary components: the form drag, skin friction drag, and base pressure drag. These together made up the core of the model, additional complexity served to increase the accuracy of the model and generalize to different projectile profiles.

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Created

Date Created
  • 2020-05