Mechanical Engineering Commons^™

Dynamics Of Asymmetrical Configurations Of Catamaran Hull Forms, Vaibhav Aribenchi

Theses and Dissertations

It is important to understand asymmetrical catamarans motions since it influences the loads which increases stress on structures while causing discomfort to passengers and crew members. Researchers so far have been mainly focused on motions characteristics of the conventional catamaran hull forms. There is scant literature or research work in the public domain on asymmetrical catamaran hull form, with regards to its seakeeping performance. This thesis undertakes a comparative analysis of the motion characteristics between newly developed alternative catamaran hull forms of different asymmetrical configurations. The asymmetrical catamarans developed from the original NPL round bilge catamaran hull forms have a …

Discrete Element Analysis Of Scb Variability: Asphalt Mixtures, David Saul Renteria

Theses and Dissertations

The Semi-Circular Bending (SCB) test was modeled using the Discrete Element Method (DEM) implemented in numerical software Particle Flow Code (PFC). The fracture analysis of the SCB was studied using two mixtures gradation, Superpave and Coarse Matrix High Binder. The aggregate phase in the model was achieved by using two-dimensional aggregate images with different angularity indexes. The study of the variability of the SCB extends to the random generation of aggregate particles and air voids in the model, in addition to changing the properties at the interface between the aggregate and mastic phases. Results indicate the strong influence of the …

An Empirical Examination Of Cognitive Chunking And Information Generation In Freehand Sketches During Design Ideation, Omar Magdy Ibrahim Zaki Mohammed Galil

Theses and Dissertations

This thesis proposes a method to measure information content of freehand sketches during design ideation based on the cognitive chunk formation. The research is broken down into two phases. The first is a protocol study to explore chunk formation in freehand sketches by novice designers while generating solutions for a novel design problem. The second is the identification of entities and functional relations explicitly expressed in the designers’ output. Next, a form neutral (F-ER) representation model is formulated, and information metrics are applied to measure the information content. This work is motivated by the notion that engineering design can be …

Casimir And Van Der Waals Effects On Electrostatically Actuated Nems Resonator Sensors, Christian Reyes

Theses and Dissertations

The behavior of nano and micro-electromechanical systems (N/MEMS) cantilever beams under electrostatic actuation is studied. The cantilever system is actuated by soft AC voltage that is set to a frequency of near half natural and near natural frequency of the beam. These actuating frequencies result in primary and parametric resonances, respectively. Two methods are used to analytically model the behavior of the cantilever. The first method is Method of Multiple Scales (MMS), which is a perturbation method that works for small parameters. The second method is the Reduced Order Method (ROM), which is a Galerkin method that works for large …

Design And Implementation Of A Pid Controller For The Low-Speed Wind Tunnel, Carlos F. Vasquez

Theses and Dissertations

The purpose of this research is to investigate the implementation of an external PID controller on an existing variable frequency motor drive (VFD) while using MODBUS communication to read/write data from a LabVIEW station. LabVIEW is the chosen user interface and programming language. It allows human-machine interfacing for the collecting, displaying of information, and automation of the system. The main objective was to develop a new controller to facilitate the operation of the wind tunnel. The current setup makes the operator set the motor frequency manually which then correlates to a test section wind velocity. This involved a calibration period …

Cfd Analysis Of Resistance Characteristics Of High-Speed Displacement Hull Forms Fitted With Hull Vane®, Venkata Karthik Avala

Theses and Dissertations

Improving the performance and resistance of a high-speed monohull forms has been of interest to Naval Architects for several decades. A considerable amount of research has been carried out in this area by using stern flaps and other appendages. This research thesis investigates the resistance characteristics of high-speed round bilge hull forms fitted with a Hull Vane® in the stern region of the vessel. The Hull Vane® is a fixed foil located below the waterline at the aft of the stern of the vessel. The Hull Vane® reduces the generation of waves at the aft and improves the vessel's motions. …

Dynamic Anchoring In Soft Regolith For Celestial Exploration, Tom Ebert

Theses and Dissertations

Recent exploration missions to celestial bodies have shown an increasing demand for surface based landers and rovers designed to perform experiments on the ground, rather than relying purely on traditional orbiting observatories. Many of the scientifically interesting locations have proven hazardous and difficult to reach and traverse, driving the need for different methods of locomotion. Some of these locations lie in deep, permanently shadowed craters or in rocky, highly uneven landscapes. Various wheeled, flying, jumping and legged rovers have been proposed, some of which have been implemented with success and problems alike. Even though the Curiosity rover has the largest …

Design Optimization And Motion Planning For Pneumatically-Actuated Manipulators, Daniel Mark Bodily

Theses and Dissertations

Soft robotic systems are becoming increasingly popular as they are generally safer, lighter, and easier to manufacture than their more rigid, traditional counterparts. These advantages allow an increased sense of freedom in both the design and operation of these platforms. In this work, we seek methods of leveraging this freedom to both design and plan motions for two different serial-chain, pneumatically actuated manipulators developed by Pneubotics, a small startup company based in San Francisco. In doing so, we focus primarily on two related endeavors: (1) the optimal kinematic design of these and other similar robots (i.e., choosing link lengths, base …

Assessing The Hydrodynamic And Economic Impacts Of Biofouling On The Hull Of Surface Vessels Using Numerical Methods, Letchi Evrard Quentin Anoman

Theses and Dissertations

Marine fouling on the hull of surface vessels is a topic of increasing importance in the maritime field for its environmental and financial impacts. Recent research developments have introduced mathematical models dealing with the frictional resistance associated with fouling, thus enabling to single out their impact on ship hydrodynamics. Herein, two implementations of these models are presented. The first implementation used Computational Fluid Dynamics to assess the additional drag induced by fouling for a specific ship model. With the software STAR CCM+, Reynolds Averaged Navier-Stokes equations have been used to model turbulence, wall laws parameters have been adapted to suit …

Non-Dimensional Modeling Of The Effects Of Weld Parameters On Peak Temperature And Cooling Rate In Friction Stir Welding, Bryan Jay Stringham

Theses and Dissertations

Methods for predicting weld properties based on welding parameters are needed in friction stir welding (FSW). FSW is a joining process in which the resulting properties depend on the thermal cycle of the weld. Buckingham's Pi theorem and heat transfer analysis was used to identify dimensionless parameters relevant to the FSW process. Experimental data from Al 7075 and HSLA-65 on five different backing plate materials and a wide range of travel speeds and weld powers was used to create a dimensionless, empirical model relating critical weld parameters to the peak temperature rise and cooling rate of the weld. The models …

Selecting Surrogate Folds For Use In Origami-Based Mechanisms And Products, Jason Tyler Allen

Theses and Dissertations

Origami-based design is increasing in popularity as its benefits and advantages become better understood and explored. However, many opportunities still exist for the application of origami principles to engineered designs, especially in the use of non-paper, thick sheet materials. One specific area utilizing thick sheet materials that is especially promising is origami-based mechanisms that require electrical power transfer applications. Many of these opportunities can be met by the use of surrogate folds. This thesis provides methods and frameworks that can be used by engineers to efficiently select and design surrogate folds for use in origami-based mechanisms and products. Surrogate folds …

Estimating Short-Term Human Intent For Physical Human-Robot Co-Manipulation, Eric Christopher Townsend

Theses and Dissertations

Robots are increasingly becoming safer and more capable. In the past, the main applications for robots have been in manufacturing, where they perform repetitive, highly accurate tasks with physical barriers that separate them from people. They have also been used in space exploration where people are not around. Due to improvements in sensors, algorithms, and design, robots are beginning to be used in other applications like materials handling, healthcare, and agriculture and will one day be ubiquitous. For this to be possible, they will need to be able to function safely in unmodelled and dynamic environments. This is especially true …

Experimental And Computational Analysis Of An Axial Turbine Driven By Pulsing Flow, Mark H. Fernelius

Theses and Dissertations

Pressure gain combustion is a form of combustion that uses pressure waves to transfer energy and generate a rise in total pressure during the combustion process. Pressure gain combustion shows potential to increase the cycle efficiency of conventional gas turbine engines if used in place of the steady combustor. However, one of the challenges of integrating pressure gain combustion into a gas turbine engine is that a turbine driven by pulsing flow experiences a decrease in efficiency. The interaction of pressure pulses with a turbine was investigated to gain physical insights and to provide guidelines for designing turbines to be …

A Physical And Computational Comparison Of Floating Breakwater Design Efficiencies For Habitat Restoration In The Indian River Lagoon, Abigail Lynn Stehno

Theses and Dissertations

This study examines the design and implementation of floating breakwaters (FB) in the Indian River Lagoon (IRL) to support and protect living shoreline restoration projects from damaging wave climates. The design significant wave climate of the IRL in a 0.6 m water depth had an incident significant wave height of 0.20 m with a wave period of 1.6 s. Based on previous studies, it has been found that habitat restoration will be successful if the wave height is reduced from 0.20 m to 0.10 m with the use of a FB structure. FB structures attenuate wave energies and are transportable, …

Empirical Study Of In-Plane Shrinkage And Bulging Of Circular Cylinders Fabricated With The Fused Deposition Modeling Additive Manufacturing Method, Kirill Martusevich

Theses and Dissertations

This thesis presents a set of empirical studies, leading to three Design for Additive Manufacturing (DfAM) tools for estimating diametric shrinkage and the longitudinal variation of diameter in circular cylinders produced by the Fused-Deposition Modeling (FDM) method. First, four experiments are conducted by additively printing 50 cylinders and taking 1900 measurements in order to study the variation of diametric shrinkage along the cylinder axis and the variation of shrinkage as functions of four parameters of the cylinder: top and bottom thicknesses, diameter, height, and shell thickness. These four subjects of study are addressed as five research questions and are answered …

Balancing Technical And User Objectives In The Design Of Improved Biomass Cookstoves For Developing Regions Of The World, Kendall Steven Thacker

Theses and Dissertations

Over the past decade a large amount of research has been dedicated in academic literature to improving the technical capabilities of improved cookstoves; primarily the performance efficiency and reduction of emissions. Unfortunately, as published literature has highlighted, the trade-offs that result from placing such a concentrated emphasis on these technical objectives is that improved cookstoves lack the same level of usability as traditional cookstoves. Thus, users often return to using their traditional stoves and the potential impact of the improved cookstoves is never fully realized. In order for improved cookstoves to have greater impact, there must be better balance between …

Hybrid State-Transactional Database For Product Lifecycle Management Features In Multi-Engineer Synchronous Heterogeneous Computer-Aided Design, Devin James Shumway

Theses and Dissertations

There are many different programs that can perform Computer Aided Design (CAD). In order for these programs to share data, file translations need to occur. These translations have typically been done by IGES and STEP files. With the work done at the BYU CAD Lab to create a multi-engineer synchronous heterogeneous CAD environment, these translation processes have become synchronous by using a server and a database to manage the data. However, this system stores part data in a database. The data in the database cannot be used in traditional Product Lifecycle Management systems. In order to remedy this, a new …

Principles And Insights For Design For The Developing World, Amy Eleanor Wood

Theses and Dissertations

This dissertation collects principles and insights from various sources related to design for the developing world. These principles and insights form part of the foundation that can guide other engineers working in this area. The sources are the published literature, practitioners, non-governmental organizations, and our own field studies. From the engineering literature, we identified nine principles to guide engineers as they design poverty alleviating products for developing communities. Each principle is articulated, supporting literature is described, an in-depth example from the literature is given, followed by suggestions for how the principle can be applied to day-to-day engineering activities. Next, the …

An Analytical Model To Predict The Length Of Oxygen-Assisted, Swirled, Coal And Biomass Flames, David Arthur Ashworth

Theses and Dissertations

Government regulations to reduce pollutants and increasing environmental awareness in the power generation industry have encouraged coal power plants to begin firing biomass in their boilers. Biomass generally consists of larger particles which produce longer flames than coal for a given burner. The length of the flame is important in fixed-volume boilers because of its influence on heat transfer, corrosion, deposition, and pollutant formation. Many pulverized fuel burners employ a series of co-annular tubes with various flows of fuel and air to produce a stabilized flame. A variable swirl burner with three co-annular tubes, each of variable diameter, has been …

Design Of A 3d Printable Mechanical Time Simulating Solar System Model For Use In Stem Education, Mark Bedford Moffett

Theses and Dissertations

The use of designed tools to assist with relating abstract ideas to reality is now a possibility with the use of the modern manufacturing method of 3D printing. The inner four planets’ natural orbital periods with respect to Earth were modeled in SolidWorks and then fabricated using 3D printing. A 3D printable mechanical time simulating solar system model used in science, technology, engineering, and mathematics (STEM) could assist with the user’s understanding of the history of science, planetary orbital mechanics, gearing ratios, 3D printing, and systematically constructing a project using instructions. This paper describes the design of a 3D printable …

The Development Of A Vertical-Axis Wind Turbine Wake Model For Use In Wind Farm Layout Optimization With Noise Level Constraints, Eric Blaine Tingey

Theses and Dissertations

This thesis focuses on providing the means to use vertical-axis wind turbines (VAWTs) in wind farms as an alternative form of harnessing wind energy in offshore and urban environments where both wake and acoustic effects of turbines are important considerations. In order for VAWTs to be used in wind farm layout analysis and optimization, a reduced-order wake model is needed to calculate velocities around a turbine quickly and accurately. However, a VAWT wake model has not been available to accomplish this task. Using vorticity data from computational fluid dynamic (CFD) simulations of VAWTs and cross-validated Gaussian distribution and polynomial surface …

Hydrodynamic Resistance Of A Surfboard: An Analytical, Empirical, And Statistical Analysis, Andrew Leonard Kledzik

Theses and Dissertations

The objective of the present study defines a drag coefficient for a 9’0” surfboard. The hydrodynamic drag of a surfboard is derived from theory outlining the mathematical foundation used. Analytical solutions provide values for boundary layer thickness, momentum flux width, shear stress, drag force and the drag coefficient. This study also examines maximum velocities attainable from in-situ observations of surfers paddling in a controlled environment. The theoretical predictions are compared with experimental observations of surfboard resistance; while simultaneously validating instrumentation and methods of measurement. A number of problems are highlighted, ranging from mathematical problems on turbulent flow analysis to impacts …

Development Of High Efficiency Dry Powder Inhalers For Use With Spray Dried Formulations, Dale Farkas

Theses and Dissertations

Dry powder inhalers (DPIs) are advantageous for delivering medication to the lungs for the treatment of respiratory diseases because of the stability of the powders, relative low cost, synchronization of inhalation and dose delivery, and many design options that can be used for optimization. However, currently marketed DPIs are very inefficient in delivering medications to the lungs. This study has developed multiple new high efficiency DPIs for use with spray dried excipient enhanced growth (EEG) powder formulations based on the following platforms: capsule-based for oral inhalation, high-dose for oral inhalation, inline with 3D rod array dispersion, and inline with capillary …

Computational Wave Field Modeling Using Sequential Mapping Of Poly-Crepitus Green’S Function In Anisotropic Media, Sajan Shrestha

Theses and Dissertations

In this thesis, a meshless semi-analytical computational method is presented to compute the ultrasonic wave field in the generalized anisotropic material while understanding the physics of wave propagation in detail. To understand the wave-damage interaction in an anisotropic material, it is neither feasible nor cost-effective to perform multiple experiments in the laboratory. Hence, recently the computational nondestructive evaluation (CNDE) received much attention to performing the NDE experiments in a virtual environment. In this thesis, a fundamental framework is constructed to perform the CNDE experiment of a thick composite specimen in a Pulse-Echo (PE) mode. To achieve the target, the following …

Instability In Nonequilibrium And Nonthermal Plasma Discharges, Rajib Mahamud

Theses and Dissertations

Microplasma, or plasma in micron scale interelectrode separation, is an effective way to attain nonthermal plasma operation at atmospheric and higher pressure. However, the small size causes the effect of other operating parameters to be crucial in stable operation and make the microplasma discharge system to be susceptible to instabilities. The two major instabilities that are commonly observed are the instability in the negative differential resistance (NDR) region and the Striations or the ionization waves. The physics and reaction kinetics of NDR instability for high pressure system is not well understood. This study pursues both experimental characterization and development of …

Progressive Failure Analysis Of Composite Materials Using The Puck Failure Criteria, Karan Kodagali

Theses and Dissertations

Fiber reinforced composites have been used in various engineering structures and applications especially in naval, automotive, aeronautical and sports industries. These composite materials generally exhibit brittle damage behavior. The anisotropy in the material and different kinds of failure mechanisms make it difficult to accurately characterize the behavior of composite materials. The present work aims to verify and apply the Puck Failure Criteria using the commercially available finite element package ABAQUS by writing a user-material subroutine in FORTRAN. The model is implemented with different post failure degradation schemes.

In the present work, the progressive failure on composite materials in analyzed using …

Fiber Optic Guided Wave Sensors For Structural Health Monitoring, Erik Frankforter

Theses and Dissertations

Risks and costs associated with aging infrastructure have been mounting, presenting a clear need for innovative damage monitoring solutions. One of the more powerful damage monitoring approaches involves using ultrasonic guided waves which propagate through a structure and carry damage-related information to permanently bonded sensors. Ultrasonic fiber-optic sensors are one of the most promising technologies for this application: they are immune to electromagnetic interference, present no ignition hazard, and transmit their data over tens of kilometers. However, before they can be widely employed, several limitations need to be overcome: poor sensitivity, unidirectional sensing, and loss of ultrasonic functionality due to …

Numerical Analysis Of Phase Change, Heat Transfer And Fluid Flow Within Miniature Heat Pipes, Mehdi Famouri

Theses and Dissertations

Heat pipes with broad applications in thermal systems have the ability to provide effective heat transport with minimal losses in over reasonable distances due to their passive nature. Their exceptional flexibility, simple fabrication, and easy control, not to mention, all without any external pumping power make them especially attractive in electronics cooling. Heat pipe development is motivated to overcome the need to presumably manage thermal dissipation in progressively compressed and higher-density microelectronic components, while preserving the components temperatures to specification.

Computation of flow and heat transfer in a heat pipe is complicated by the strong coupling among the velocity, pressure …

Behavioral Responses Of Sub-Adult Atlantic Sturgeon (Acipenser Oxyrinchus Oxyrinchus) To Electromagnetic And Magnetic Fields Under Laboratory Conditions, Andrew Mcintyre Iii

Theses and Dissertations

Electromagnetic fields (EMF) produced by high voltage (HV), submarine transmission cables leading from offshore wind energy generation facilities could affect foraging or migratory behaviors of electro-receptive fishes, including endangered Atlantic Sturgeon. However, no published studies have quantitatively evaluated the possible behavioral effects of EMF exposure on sturgeon during residence in coastal waters. This study evaluated behavioral responses by sub-adult Atlantic Sturgeon to electromagnetic and magnetic fields under controlled laboratory conditions. Fabricated EMF generators were used to emulate a range of field EMF conditions that migratory fishes could encounter in proximity to submarine HV sources. Sensor arrays and digital video recorders …

Promotional Effect Of Molten Carbonates On Proton Conductivity And Oxygen Reduction Reaction – An Experimental And Computational Study, Xiaolei Xiong

Theses and Dissertations

Recent research of Solid oxide fuel cells (SOFCs) is aimed to lower the operating temperature to an intermediate temperature (IT) range of 500 to 700^oC, while maintaining a proper performance. This Ph.D. research project investigates the promotional effects of alkaline carbonate eutectics on the proton conductivity of proton conducting electrolytes and cathodic ORR reactivity in SOFCs by both experimental and computational methods. The ionic conductivity of the MC-BZY composite above 500^oC increases with the higher loading of MC. The sample exhibited nearly a factor of two higher conductivity in H₂-containing atmosphere than in air. …