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Articles 421 - 450 of 1342

Full-Text Articles in Mechanical Engineering

Design And Manufacture Of Mesoscale Robot-Actuated Surgical Instruments, Clayton L. Grames Nov 2015

Design And Manufacture Of Mesoscale Robot-Actuated Surgical Instruments, Clayton L. Grames

Theses and Dissertations

Minimally Invasive Surgery (MIS) is a growing field including both laparoscopic androbotic operations. Surgeons and engineers are making continual efforts to reduce the negative effects of procedures on patients. Reducing the size of the surgical instruments is one effective method pursued in this effort. When the instruments approach 3 mm in diameter, they reach a threshold where the entry incisions can be small enough that no scar is left on the patient. Laparoscopic instruments on this scale exist but typically lack wrist articulation and only have 1 degree of freedom (DoF). Alternatively, robotic surgical instruments can achieve high levels of …

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Using Star-Ccm+ To Evaluate Multi-User Collaboration In Cfd, Kasey Johnson Webster Oct 2015

Using Star-Ccm+ To Evaluate Multi-User Collaboration In Cfd, Kasey Johnson Webster

Theses and Dissertations

The client-server architecture of STAR-CCM+ allows multiple users to collaborate on a simulation set-up. The effectiveness of collaboration with this architecture is tested and evaluated on five models. The testing of these models is a start to finish set-up of an entire simulation excluding computational time for generating mesh and solving the solution. The different models have distinct differences which test every operation that would be used in a general CFD simulation. These tests focus on reducing the time spent preparing the geometry to be meshed, including setting up for a conformal mesh between multiple regions in conjugate heat transfer …

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Design And Validation Of A Complex Loading Whole Spinal Segment Bioreactor, Amanda Marie Beatty Oct 2015

Design And Validation Of A Complex Loading Whole Spinal Segment Bioreactor, Amanda Marie Beatty

Theses and Dissertations

Intervertebral disc (IVD) degeneration is a prevalent health problem that is highly linked to back pain. To understand the disease and tissue response to therapies, ex-vivo whole IVD organ culture systems have recently been introduced. The goal of this study was to develop and validate a whole spinal segment culturing system that loads the disc in complex loading similar to the in-vivo condition, while preserving the adjacent endplates and vertebral bodies. The complex loading applied to the spinal segment was achieved with three pneumatic cylinders. The pneumatic cylinders were rigidly attached to two triangular alumni plates at each corner, comprising …

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Rigidly Foldable Origami Gadgets And Tessellations, Thomas A. Evans, Robert J. Lang, Spencer P. Magleby, Larry L. Howell Sep 2015

Rigidly Foldable Origami Gadgets And Tessellations, Thomas A. Evans, Robert J. Lang, Spencer P. Magleby, Larry L. Howell

Faculty Publications

Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented.

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An Approach For Designing Origami-Adapted Products With Aerospace Mechanism Examples, Jessica Morgan Sep 2015

An Approach For Designing Origami-Adapted Products With Aerospace Mechanism Examples, Jessica Morgan

Theses and Dissertations

The objective of this research is to develop a design process for origami-adapted products and demonstrate it using aerospace mechanism examples. Origami-adapted design is a type of origami-based design. Origami-based design ranges from abstract to concrete applications of origami to design and includes: origami-inspired design, origami-adapted design, and origami-applied design. Origami-adapted design adapts origami fold patterns into products while preserving functionality. Some of the desirable attributes of origami that are sought after in design include: 1) reduced number of parts, 2) stowability, 3) deployability, 4) transportability, 5) manufacturability from a flat sheet of material, 6) ease of miniaturization, 7) a …

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Neutral Parametric Canonical Form For 2d And 3d Wireframe Cad Geometry, Robert Steven Freeman Aug 2015

Neutral Parametric Canonical Form For 2d And 3d Wireframe Cad Geometry, Robert Steven Freeman

Theses and Dissertations

The challenge of interoperability is to retain model integrity when different software applications exchange and interpret model data. Transferring CAD data between heterogeneous CAD systems is a challenge because of differences in feature representation. A study by the National Institute for Standards and Technology (NIST) performed in 1999 made a conservative estimate that inadequate interoperability in the automotive industry costs them $1 billion per year. One critical part of eliminating the high costs due to poor interoperability is a neutral format between heterogeneous CAD systems. An effective neutral CAD format should include a current-state data store, be associative, include the …

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Improving The Suction Performance And Stability Of An Inducer With An Integrated Inlet Cover Bleed System Known As A Stability Control Device, Ryan K. Lundgreen Aug 2015

Improving The Suction Performance And Stability Of An Inducer With An Integrated Inlet Cover Bleed System Known As A Stability Control Device, Ryan K. Lundgreen

Theses and Dissertations

The performance of an inducer with the integration of an inlet cover bleed system known as a stability control device (SCD) is investigated using computational fluid dynamics. Inducers are the first stage of high suction performance pumps and are designed to operate under cavitating conditions. Improvements in design have allowed inducers to operate stably with low inlet head conditions, however, cavitation instabilities ultimately lead to pump failure. It has been shown that inducers that employ an SCD fully suppress cavitation instabilities.The performance of an inducer is explored at both on- and off-design flow coefficients, where the flow coefficient is a …

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Jet And Droplet Impingement On Superhydrophobic Surfaces, Jonathan Glenn Stoddard Aug 2015

Jet And Droplet Impingement On Superhydrophobic Surfaces, Jonathan Glenn Stoddard

Theses and Dissertations

The effect of superhydrophobicity on liquid water impingement on a flat horizontal surface was explored. The surfaces combined a hydrophobic surface chemistry with a patterned microstucture in order to produce high contact angles with water. Three sets of experiments were performed, one for jet impingement and two for droplet impingement, which advance previous work in characterizing the interaction of water and superhydrophobic surfaces.Jet impingement experiments were performed to characterize a transitional regime between an unsubmerged and a completely submerged superhydrophobic surface by varying an imposed downstream depth. For low downstream depths, the surface remained unsubmerged and displayed only break up …

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Composition Based Modaling Of Silicone Nano-Composite Strain Gauges, Daniel Alexander Baradoy Jul 2015

Composition Based Modaling Of Silicone Nano-Composite Strain Gauges, Daniel Alexander Baradoy

Theses and Dissertations

In this work a review of the technology surrounding high deflection strain sensing with an emphasis on that of a recently developed nickel nano-composite strain sensor is presented. A new base silicone material was identified for the nickel nano-composite strain sensor that improves its mechanical stiffness and conductive properties. A previously identified cyclic creep concern was mitigated through preconditioning and the use of adhered backing materials. Through a block design experiment the strain/resistance curves for the strain sensors were characterized over a wide range of nano-filler material compositions. An analytical model was developed based on observation that the resistance of …

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Transport Enhancement Of Rate-Limited Chemical Reactions Via Pt-Decorated, Carbon Nanotube Microarray Membranes, Kevin M. Marr Jul 2015

Transport Enhancement Of Rate-Limited Chemical Reactions Via Pt-Decorated, Carbon Nanotube Microarray Membranes, Kevin M. Marr

Theses and Dissertations

Rate limited chemical reactions can be enhanced by improving the mass transport of the suspended analyte to the catalytic (or electrocatalytic) surface. While many attempts have been made to enhance this mass transport, these approaches are limited to utilizing only two enhancement methods – increasing available catalytic surface area, and increasing the flow of analyte in solution. Flow through high aspect ratio microstructures, however, would provide additional mass transport enhancement via boundary layer confinement. Platinum functionalized carbon nanotube microarray membranes (Pt-CNT-MMs) offer enhanced mass transport via all three methods, and were fabricated for demonstration in a H2O2 sample system, for …

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Geometry And Material Properties Of Vocal Fold Models, Kimberly Ann Stevens Jul 2015

Geometry And Material Properties Of Vocal Fold Models, Kimberly Ann Stevens

Theses and Dissertations

Voiced communication plays a fundamental role in society. Voice research seeks to improve understanding of the fundamental physics governing voice production, with the eventual goal of improving methods to diagnose and treat voice disorders. For this thesis, three different aspects of voice production research were studied. First, porcine vocal fold medial surface geometry was determined, and the three-dimensional geometric distortion induced by freezing the larynx, especially in the region of the vocal folds, was quantified. It was found that porcine vocal folds are qualitatively geometrically similar to canine and human vocal folds, as well as commonly used models, and that …

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Temperature Measurement Using Infrared Spectral Band Emissions From H2o, Daniel Jared Ellis Jul 2015

Temperature Measurement Using Infrared Spectral Band Emissions From H2o, Daniel Jared Ellis

Theses and Dissertations

Currently there is no known method for accurately measuring the temperature of the gas phase of combustion products within a solid fuel flame. The industry standard is a suction pyrometer and thermocouple which is intrusive, both spatially and temporally averaging, and difficult to use. In this work a new method utilizing the spectral emission from water vapor is investigated through modeling and experimental measurements. This method was demonstrated along a 0.75m line of sight, averaged over 1 minute in the products of a natural gas flame but has the potential to produce a spatial resolution on the order of 5 …

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Effect Of Airfoil And Composite Layer Thicknesses On An Aerostructural Blade Optimization For Wind Turbines, Ryan Barrett, Ian Freeman, Andrew Ning Jul 2015

Effect Of Airfoil And Composite Layer Thicknesses On An Aerostructural Blade Optimization For Wind Turbines, Ryan Barrett, Ian Freeman, Andrew Ning

Faculty Publications

The purpose of this research is to enhance the performance of wind turbine blades by exploring the effect of adding airfoil and material layer thicknesses to the optimization design process. This is accomplished by performing an aerostructural blade optimization to minimize mass over annual energy production and thereby reduce the cost of energy. Changing airfoil thickness allows the airfoil shape to evolve as part of the optimization. The airfoil thicknesses are allowed to vary within two airfoil families, the TU-Delft and NACA 64-series, that are used in the NREL 5-MW reference turbine. Both experimental wind tunnel and computational data are …

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Wind Farm Layout Optimization Using Sound Pressure Level Constraints, Eric Tingey, Jared Thomas, Andrew Ning Jul 2015

Wind Farm Layout Optimization Using Sound Pressure Level Constraints, Eric Tingey, Jared Thomas, Andrew Ning

Faculty Publications

This project explored wind farm layout optimization using turbine acoustic and wake models. For two existing wind farms, the position of each wind turbine was optimized to maximize power output while constraining noise. Semi-empirical calculations were used for both the acoustic and wake models to predict how the turbine noise and wake disturbances propagated downstream. Turbine layout was optimized using a sequential quadratic programming optimizer called SNOPT. The optimization was able to constrain the noise level of the wind farms with a small impact on power output.

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Comparison Of Two Wake Models For Use In Gradient-Based Wind Farm Layout Optimization, Jared Thomas, Eric Tingey, Andrew Ning Jul 2015

Comparison Of Two Wake Models For Use In Gradient-Based Wind Farm Layout Optimization, Jared Thomas, Eric Tingey, Andrew Ning

Faculty Publications

Wind farm layout has a significant impact on the productivity of a wind farm. To ensure that the turbines are placed in the most advantageous arrangement, optimization algorithms are often used during the layout design process. Depending on the wake model used for the optimization, optimizing the layout can be time intensive or potentially inaccurate. In this paper we present a comparison of optimization results using two simple wake models, the FLORIS model and the Jensen model. Results highlight some of the key similarities and differences of layout optimization results when different wake models are used.

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Curved-Folding-Inspired Deployable Compliant Rolling-Contact Element (D-Core), Todd Nelson, Robert Lang, Spencer P. Magleby, Larry L. Howell Jun 2015

Curved-Folding-Inspired Deployable Compliant Rolling-Contact Element (D-Core), Todd Nelson, Robert Lang, Spencer P. Magleby, Larry L. Howell

Faculty Publications

This work describes a deployable compliant rolling-contact element joint (DCORE joint) that employs curved-folding origami techniques to enable transition from a flat to deployed state. These deployable joints can be manufactured from a single sheet of material. Two fundamental configurations of the D-CORE are presented. The first configuration allows for motion similar to that of a Jacob’s ladder when the joint is in a planar state while achieving the motion of a CORE when in the deployed state. The second configuration constrains all degrees of freedom to create a static structure when the joint is in the planar state and …

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Investigation Of Parameters Affecting The Nanoinjection Of Hela 229 Cancer Cells, Tyler E. Lewis Jun 2015

Investigation Of Parameters Affecting The Nanoinjection Of Hela 229 Cancer Cells, Tyler E. Lewis

Theses and Dissertations

The ability to deliver sequences of DNA and other molecular loads across the membrane of a cell and into its nucleus is an area of interest in the medical community. One of its many applications is that of gene therapy. In contrast to other forms of treatment, gene therapy seeks to treat diseases at the cellular level. The success of these treatments depends on the technologies for cell transfection that are available. Physical methods are sometimes able to overcome poor efficiencies of chemical methods and the safety concerns of viral methods, but are usually impractical due to the limited number …

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Temperature Control In Friction Stir Welding Using Model Predictive Control, Brandon Scott Taysom Jun 2015

Temperature Control In Friction Stir Welding Using Model Predictive Control, Brandon Scott Taysom

Theses and Dissertations

Temperature is a very important process parameter in Friction Stir Welding (FSW), but until lately active control of temperature has not been practiced. Recently, temperature control via a PID controller has proven to be effective. Model Predictive Control (MPC) is a control method that holds promise, but has not been attempted in FSW before. Two different model forms are developed for MPC and are evaluated. The first is a simple first-order plus dead time (FOPDT) model. The second is the Hybrid Heat Source model and is more complex; it combines the heat source method and a 1D discretized thermal model …

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On The Free Surface Skipping Characteristics Of Highly Deformable Elastic Spheres, Randy C. Hurd Jun 2015

On The Free Surface Skipping Characteristics Of Highly Deformable Elastic Spheres, Randy C. Hurd

Theses and Dissertations

When a highly deformable elastic sphere impacts a water surface at an oblique angle it can skip several times in a manner similar to a skipping stone. However, this sphere seems to skip more readily and with more ease than a traditional skipping stone. This thesis examines the improved skipping characteristics of highly deformable elastic spheres made from cured silicone rubber. The effect of impact velocity, impact angle, sphere diamter and material shear modulus on ricochet trajectory is experimentally examined using high speed photography and image processing techniques. Experimental evaluation shows that deformation is the primary contributor to an increased …

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Using The Offset Panel Technique To Develop Innovative Origami-Based Applications, Michael Robert Morgan Jun 2015

Using The Offset Panel Technique To Develop Innovative Origami-Based Applications, Michael Robert Morgan

Theses and Dissertations

Origami, the art of folding paper, was once only an art form. In recent years, it has collided with the world of engineering and is acting as a source of inspiration for solutions to various engineering problems. Paper, the typical material used in the art form, is thin and works well for origami, but is not often suitable for use in engineering. Researchers have developed a handful of methods for accommodating thick/rigid materials in origami design. Most of these preserve only the kinematics of the model or its range of motion. Not only does the offset panel technique (OPT) preserve …

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High Aspect Ratio, Carbon Nanotube Membranes Decorated With Pt Nanoparticle Urchins For Micro Underwater Vehicle Propulsion Via H2O2 Decomposition, Kevin M. Marr, Bolin Chen, Eric J. Mootz, Jason Geder, Marius Pruessner, Brian J. Melde, Richard R. Vanfleet, Igor L. Medintz, Brian D. Iverson, Jonathan C. Claussen Jun 2015

High Aspect Ratio, Carbon Nanotube Membranes Decorated With Pt Nanoparticle Urchins For Micro Underwater Vehicle Propulsion Via H2O2 Decomposition, Kevin M. Marr, Bolin Chen, Eric J. Mootz, Jason Geder, Marius Pruessner, Brian J. Melde, Richard R. Vanfleet, Igor L. Medintz, Brian D. Iverson, Jonathan C. Claussen

Faculty Publications

The utility of unmanned Micro Underwater Vehicles (MUVs) is paramount for exploring confined spaces, but their spatial agility is often impaired when maneuvers require burst-propulsion. herein we develop high-aspect ratio (150:1), multi-walled carbon nanotube microarray membranes (CNT-MMs) for propulsive, MUV thrust generation by the decomposition of hydrogen peroxide (H2O2). The CNT-MMs are grown via chemical vapor deposition with diamond shaped pores (nominal diagonal dimensions of 4.5 × 9.0 [µm]) and subsequently decorated with urchin-like, platinum (Pt) nanoparticles via a facile, electroless, chemical deposition process. The Pt-CNT-MMs display robust, high catalytic ability with an effective activation energy …

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Integrating Synchronous Collaborative Applications With Product Lifecycle Management Workflows, Jordan Lowell Johnson Jun 2015

Integrating Synchronous Collaborative Applications With Product Lifecycle Management Workflows, Jordan Lowell Johnson

Theses and Dissertations

Product Lifecycle Management (PLM) systems are used by thousands of engineering companies world wide. Improving these systems will have a drastic and global effect. One possible improvement is to integrate synchronous collaborative applications with PLM systems. These applications allow multiple people to work on a single digital object simultaneously. They have already been shown to reduce the time a task requires. Using these applications to complete a project will reduce the project time. However, simply including synchronous collaborative applications within a PLM system ignores powerful benefits that could provide further time-saving benefits. The integration must allow improved awareness at the …

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A Study Of Carbon Infiltrated Carbon Nanotubes Fabricated On Convex Cylindrical Substrates For The Creation Of A Coronary Stent, Warren Beecroft Robison Jun 2015

A Study Of Carbon Infiltrated Carbon Nanotubes Fabricated On Convex Cylindrical Substrates For The Creation Of A Coronary Stent, Warren Beecroft Robison

Theses and Dissertations

This research explores the minimizing of cracks in the fabrication of carbon-infiltrated carbon nanotube (CI-CNT) forests on cylindrical rods for the purposes of creating a CI-CNT coronary stent. It is a continuation of the work begun by Jones [1] and Skousen [2] whose work included the creation of a feasible CI-CNT coronary stent on a planar surface. The current research was performed in two parts: 1) growth on the whole circumference of the rod for ~20mm in length and 2) growth in lines and patterns. Experiments were done on either a 309 or 304 stainless steel rod ~3mm in diameter.The …

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A Collaborative Conceptual Aircraft Design Environment For The Design Of Small-Scale Uavs In A Multi-University Setting, Joseph Samuel Becar May 2015

A Collaborative Conceptual Aircraft Design Environment For The Design Of Small-Scale Uavs In A Multi-University Setting, Joseph Samuel Becar

Theses and Dissertations

In today's competitive global market, there is an ever-increasing demand for highly skilled engineers equipped to perform in teams dispersed over several time-zones by geography. Aerospace Partners for the Advancement of Collaborative Engineering (AerosPACE) is a senior design capstone program co-developed by academia and industry to help students develop the necessary skills to excel in the aerospace industry by challenging them to design, build, and fly an unique unmanned aerial vehicle (UAV). Students with little to no experience designing UAVs are put together in teams with their peers from geographically dispersed universities. This presents a significant challenge for the students …

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Ligament Model Fidelity In Finite Element Analysis Of The Human Lumbar Spine, Mitchell Scott Hortin May 2015

Ligament Model Fidelity In Finite Element Analysis Of The Human Lumbar Spine, Mitchell Scott Hortin

Theses and Dissertations

The purpose of this project is to quantify the effects of increasing spinal ligament fidelity on the mechanics of the human lumbar spine using finite element analysis (FEA). In support of this goal, a material characterization study was completed to provide anisotropic, nonlinear material parameters for the human anterior longitudinal ligament. (ALL). Cadaveric samples of the human ALL were tested using a punch test technique. Multi- axial force-deformation data were gathered and fit to a commonly used transversely isotropic material model using an FEA system identification routine. The resulting material parameters produced a curve that correlated well with the experimental …

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Globally Consistent Map Generation In Gps-Degraded Environments, Paul William Nyholm May 2015

Globally Consistent Map Generation In Gps-Degraded Environments, Paul William Nyholm

Theses and Dissertations

Heavy reliance on GPS is preventing unmanned air systems (UAS) from being fully inte- grated for many of their numerous applications. In the absence of GPS, GPS-reliant UAS have difficulty estimating vehicle states resulting in vehicle failures. Additionally, naively using erro- neous measurements when GPS is available can result in significant state inaccuracies. We present a simultaneous localization and mapping (SLAM) solution to GPS-degraded navigation that al- lows vehicle state estimation and control independent of global information. Optionally, a global map can be constructed from odometry measurements and can be updated with GPS measurements while maintaining robustness against outliers.We detail …

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Concurrent Engineering Through Parallelization Of The Design-Analysis Process, Eric Joseph Wardell May 2015

Concurrent Engineering Through Parallelization Of The Design-Analysis Process, Eric Joseph Wardell

Theses and Dissertations

The disconnect between the way CAD and analysis applications handle model geometry has long been a hindrance to engineering design. Current industry practices often utilize outdated forms of geometry transfer between these different engineering software applications such as neutral file formats and direct translations. Not only to these current practices slow the engineering design process but they also hinder the integration of design and analysis programs.This thesis proposes a new, multi-user, integrated design-analysis architecture which allows auxiliary functions such as analysis and computer-aided manufacturing to be better connected with the computer-aided design. It is hypothesized that this new architecture will …

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An Automated Method For Hot-To-Cold Geometry Mapping, Brandon Levi Doolin May 2015

An Automated Method For Hot-To-Cold Geometry Mapping, Brandon Levi Doolin

Theses and Dissertations

An Automated Method for Hot-to-Cold Geometry Mapping.

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An Investigation Of Off-Design Operation In High Suction Performance Inducers, Ryan Collins Cluff May 2015

An Investigation Of Off-Design Operation In High Suction Performance Inducers, Ryan Collins Cluff

Theses and Dissertations

Three-dimensional two-phase unsteady CFD simulations were run on three and four-blade inducers for the purpose of analyzing differences in cavitation stability at design and off-design flow rates. At design flow rates, there were very small differences between the breakdown curves for the three and four-bladed inducers. However, at lower cavitation numbers, the three-bladed inducer exhibited up to three times the rotor forces than the four-bladed inducer. When moving to off-design flow rates, both inducers experienced multiple modes of cavitation instabilities including rotating cavitation, alternate-blade cavitation, and cavitation surge. The four-bladed inducer began experiencing the formation of these modes of instability …

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A Multi-Objective Optimization Method For Maximizing The Value Of System Evolvability Under Uncertainty, Jason Daniel Watson May 2015

A Multi-Objective Optimization Method For Maximizing The Value Of System Evolvability Under Uncertainty, Jason Daniel Watson

Theses and Dissertations

System evolvability is vital to the longevity of large-scale complex engineered systems. The need for evolvability in complex systems is a result of their long service lives, rapid advances to their integrated technologies, unforeseen operating conditions, and emerging system requirements. In recent years, quantifiable metrics have been introduced for measuring the evolvability of complex systems based on the amount of excess capability in the system. These metrics have opened opportunities for optimization of systems with evolvability as an objective. However, there are several aspects of such an optimization that require further consideration. For example, there is a trade-off between the …

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