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Mechanical Engineering

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Brigham Young University

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2012

Articles 1 - 8 of 8

Full-Text Articles in Engineering

Spherical Lamina Emergent Mechanisms, Samuel E. Wilding, Larry L. Howell, Spencer P. Magleby Oct 2012

Spherical Lamina Emergent Mechanisms, Samuel E. Wilding, Larry L. Howell, Spencer P. Magleby

Faculty Publications

Lamina emergent mechanisms (LEMs) are compliant mechanisms that can be manufactured from planar materials and are capable of motion out of the plane of manufacture. Spherical LEMs combine the unique motion of spherical mechanisms with the compactness and simple topology of LEMs. The fundamentals of spherical LEMs are discussed in this work. It is found that 21 of the 33 possible spherical 4R types can be spherical LEMs. A classification based on these 21 possible types is developed. This classification is used to predict motion capabilities of spherical 6R, and Equintet mechanisms. It is also applied to arrays of spherical …

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Introduction Of Planar Compliant Joints Designed For Combined Bending And Axial Loading Conditions In Lamina Emergent Mechanisms, Samuel E. Wilding, Larry L. Howell, Spencer P. Magleby Oct 2012

Introduction Of Planar Compliant Joints Designed For Combined Bending And Axial Loading Conditions In Lamina Emergent Mechanisms, Samuel E. Wilding, Larry L. Howell, Spencer P. Magleby

Faculty Publications

This work introduces three joints to allow motion in lamina emergent mechanisms (LEMs) that were designed to have minimal parasitic motion under tension, compression, and a combination of tension and compression loading. Closed-form models of the joints were developed and combined with optimization algorithms for maximum flexibility in bending and then modeled using finite element analysis (FEA). The FEA results were used to predict the stiffness of the joints in bending, tension, and compression. As a baseline, lamina emergent torsional (LET) joints were designed to match the bending stiffness of each of the joints, so that the tensile-compressive performance could …

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Thermal And Mechanical Properties Of Nitrate Thermal Storage Salts In The Solid-Phase, Brian D. Iverson, Scott T. Broome, Alan M. Kruizenga, Joseph G. Cordaro Oct 2012

Thermal And Mechanical Properties Of Nitrate Thermal Storage Salts In The Solid-Phase, Brian D. Iverson, Scott T. Broome, Alan M. Kruizenga, Joseph G. Cordaro

Faculty Publications

Implementation of molten salt compounds as the heat transfer fluid and energy storage medium provides specific benefits to energy collection and conversion. Nitrate salts have been identified as a strong candidate for energy transfer and storage and have been demonstrated for use in these applications over time. As nitrate salts have solidification temperatures above ambient, concern for recovery from salt freezing events has instigated efforts to understand and predict this behavior. Accurate information of salt property behavior in the solid-phase is necessary for understanding recovery from a freeze event as well as for phase change thermal energy storage applications. Thermal …

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Relative Navigation And Control Of A Hexacopter, Timothy Mclain, Randal W. Beard, Robert C. Leishman, John Macdonald May 2012

Relative Navigation And Control Of A Hexacopter, Timothy Mclain, Randal W. Beard, Robert C. Leishman, John Macdonald

Faculty Publications

This paper discusses the progress made on developing a multi-rotor helicopter equipped with a vision-based ability to navigate through an a priori unknown, GPS-denied environment. We highlight the backbone of our system, the relative estimation and control. We depart from the common practice of using a globally referenced map, preferring instead to keep the position and yaw states in the EKF relative to the current map node. This relative navigation approach allows simple application of sensor updates, natural characterization of the transformation between map nodes, and the potential to generate a globally consistent map when desired. The EKF fuses view …

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Aircraft Route Optimization For Heterogeneous Formation Flight, Jia Xu, Andrew Ning, Geoffrey Bower, Ilan Kroo Apr 2012

Aircraft Route Optimization For Heterogeneous Formation Flight, Jia Xu, Andrew Ning, Geoffrey Bower, Ilan Kroo

Faculty Publications

We examine the value of extended formation flight in the context of airline operations. The study is based on a bi-level route optimization framework. The aircraft performance model includes the effects of rolled-up wakes, formation heterogeneity, and formation-induced compressibility effects. We incorporate airline economics to understand the trade-off between speed and drag savings in the context of formation flight. The application of formation flight to a representative South African Airlines (SAA) long-haul route network can reduce fuel burn by over 4.6% or reduce direct operating cost by 2.1%. The savings increase to 6.8% in fuel or 2.4% in cost when …

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Ballistic Imaging Of Sprays At Diesel Relevant Conditions, Jason M. Porter, S. P. Duran, T. E. Parker Jan 2012

Ballistic Imaging Of Sprays At Diesel Relevant Conditions, Jason M. Porter, S. P. Duran, T. E. Parker

Faculty Publications

Diesel engines are an important aspect of our transportation infrastructure, whose performance is greatly affected by the characteristics of the spray from their injectors. Characterization of the injector’s spray is therefore tantamount to clean-running efficient diesel motors. In this study, a ~15 ps pulsed Leopard D-10 laser is used along with an optical Kerr Cell to realize ballistic images of high-delivery-pressure dodecane sprays injected into a quiescent air environment at elevated temperature and pressure. Using CS2 as the Kerr switching media and by optimizing the overlap of the gate and imaging beams, an effective high speed shuttering effect is obtained. …

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Fluidic Assembly At The Microscale: Progress And Prospects, Nathan B. Crane, Onursal Onen, Jose Carballo, Qi Ni, Rasim Guldiken Jan 2012

Fluidic Assembly At The Microscale: Progress And Prospects, Nathan B. Crane, Onursal Onen, Jose Carballo, Qi Ni, Rasim Guldiken

Faculty Publications

Assembly permits the integration of different materials and manufacturing processes to increase system functionality. It is an essential step in the fabrication of useful systems across size scales from buildings to molecules. However, at the microscale, traditional “grasp and release” assembly methods and chemically inspired self-assembly processes are less effective due to many scaling effects. Many methods have been developed for improving microscale assembly. Often these methods include fluidic forces or the use a fluidic medium in order to enhance their performance. This paper reviews basic assembly theory and modeling methods. Three basic assembly strategies (tool-directed, process-directed, and part-directed) are …

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A Material System For Reliable Low Voltage Anodic Electrowetting, Mehdi Khodayari, Jose Carballo, Nathan B. Crane Jan 2012

A Material System For Reliable Low Voltage Anodic Electrowetting, Mehdi Khodayari, Jose Carballo, Nathan B. Crane

Faculty Publications

Electrowetting on dielectric is demonstrated with a thin spin-coated fluoropolymer over an aluminum electrode. Previous efforts to use thin spin-coated dielectric layers for electrowetting have shown limited success due to defects in the layers. However, when used with a citric acid electrolyte and anodic voltages, repeatable droplet actuation is achieved for 5000 cycles with an actuation of just 10 V. This offers the potential for low voltage electrowetting systems that can be manufactured with a simple low-cost process.

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