Mechanical Engineering Commons^™

Harvesting Magnetic Energy Using Extensional Vibration Of Laminated Magnetoelectric Plates, C. L. Zhang, J. S Yang, W. Q. Chen

Department of Engineering Mechanics: Faculty Publications

Magnetically forced extensional vibrations of laminated plates with piezoelectric and piezomagnetic layers are analyzed theoretically. It is shown that such a structure can be used to harvest magnetic energy and convert it to electric energy. The output power and the energy conversion efficiency are calculated. The load dependence of the magnetoelectric coupling coefficient is also obtained.

Real-Time Depth Sectioning: Isolating The Effect Of Stress On Structure Development In Pressure-Driven Flow, Lucia Fernandez-Ballester, Derek W. Thurman, Julia A Kornfield

Department of Engineering Mechanics: Faculty Publications

Transient structure development at a specific distance from the channel wall in a pressure-driven flow is obtained from a set of real-time measurements that integrate contributions throughout the thickness of a rectangular channel. This “depth sectioning method” retains the advantages of pressure-driven flow while revealing flow-induced structures as a function of stress. The method is illustrated by applying it to isothermal shear-induced crystallization of an isotactic polypropylene using both synchrotron x-ray scattering and optical retardance. Real-time, depth-resolved information about the development of oriented precursors reveals features that cannot be extracted from ex-situ observation of the final morphology and that are …

Convergence, Adaptive Refinement, And Scaling In 1d Peridynamics, Florin Bobaru Ph.D., Mijia Yabg Ph.D., Leonardo F. Alves M.S., Stewart A. Silling Ph.D., Ebrahim Askari Ph.D., Jifeng Xu Ph.D.

Department of Engineering Mechanics: Faculty Publications

We introduce here adaptive refinement algorithms for the non-local method peridynamics, which was proposed (in J. Mech. Phys. Solids 2000; 48:175–209) as a reformulation of classical elasticity for discontinuities and long-range forces. We use scaling of the micromodulus and horizon and discuss the particular features of adaptivity in peridynamics for which multiscale modeling and grid refinement are closely connected. We discuss three types of numerical convergence for peridynamics and obtain uniform convergence to the classical solutions of static and dynamic elasticity problems in 1D in the limit of the horizon going to zero. Continuous micromoduli lead to optimal rates of …

Evaporation Induced Two-Dimensional Buckling Within Liquid Droplet, Ziguang Chen, Maozi Liu, Gang-Yu Liu, Li Tan

Department of Engineering Mechanics: Faculty Publications

Evaporation of a liquid droplet containing a thin layer of surfactants atop could generate two-dimensional buckling on surfaces. Herringbone features were produced via embedded nanoparticle beds. We assign transient surface tension as the driving force for such a phenomenon. Considering the surfactant layer as a thin elastic film, a continuum model is employed to calculate the mechanical properties of the layer. Particularly, we estimated an elastic modulus of 4 GPa for the surfactant layer, indicating rather strong mechanical properties of these small molecules when they are close packed to form supramolecules via noncovalent binding.

Comparison Of Fuzzy Clustering Methods And Their Applications To Geophysics Data, David J. Miller, Carl A. Nelson, Molly Boeka Cannon, Kenneth P. Cannon

Department of Mechanical and Materials Engineering: Faculty Publications

Fuzzy clustering algorithms are helpful when there exists a dataset with subgroupings of points having indistinct boundaries and overlap between the clusters. Traditional methods have been extensively studied and used on real-world data, but require users to have some knowledge of the outcome a priori in order to determine howmany clusters to look for. Additionally, iterative algorithms choose the optimal number of clusters based on one of several performance measures. In this study, the authors compare the performance of three algorithms (fuzzy c-means, Gustafson-Kessel, and an iterative version of Gustafson-Kessel) when clustering a traditional data set as well as real-world …

Experimental Investigation Of A Novel Blast Wave Mitigation Device, Zhenbi Su, Wen Peng, Zhaoyan Zhang, George Gogos, Reed Skaggs, Bryan Cheeseman, Chian Fong Yen

Department of Mechanical and Materials Engineering: Faculty Publications

A novel blast wave mitigation device was investigated experimentally in this paper. The device consists of a pistoncylinder assembly. A shock wave is induced within the cylinder when a blast wave impacts on the piston. The shock wave propagates inside the device and is reflected repeatedly. The shock wave propagation process inside the device lengthens the duration of the force on the base of the device to several orders of magnitude of the duration of the blast wave, while it decreases the maximum pressure over an order of magnitude. Two types of experiments were carried out to study the blast …

Inhomogeneous Degradation Of Polymer Electrolyte Membrane In Pem Fuel Cells, Xinyu Huang, Wonseok Yoon

Faculty Publications

Membrane durability is one of the technical barriers for the commercialization of polymer electrolyte membrane (PEM) fuel cells. Membrane embrittlement (a form of mechanical weakening) can lead to the frequently observed “sudden death” behavior of PEM fuel cells. It is the objective of this study to explore the fundamental mechanisms of the mechanical weakening of perfluorosulfonic acid (PFSA) based electrolyte membranes during the accelerated degradation test.

Design Of Sea Water Heat Exchanger For Miniature Vapor Compression Cycle, James Hughes

Electronic Theses and Dissertations

Recent advances in the development of miniature vapor compression cycle components have created unique opportunities for heating and cooling applications, specifically to human physiological requirements that arise in extreme environments. Diving in very cold water between 1.7 and 5°C requires active heating because passive thermal insulation has proven inadequate for long durations. To maintain diver mobility and cognitive performance, it is desirable to provide 250 to 300 W of heat from an untethered power source. The use of a miniature vapor compression cycle reduces the amount of power (batteries or fuel cell) that the diver must carry by 2.5 times …

Droplet Flows In Microchannels Using Lattice Boltzmann Method, Amit Gupta

Electronic Theses and Dissertations

Microelectromechanical systems (MEMS) have widespread applications in medical, electronical and mechanical devices. These devices are characterized by the smallest dimension which is at least one micrometer and utmost one millimeter. Rapid progress in the manufacture and utilization of these microdevices has been achieved in the last decade. Current manufacturing techniques of such devices and channels include surface silicon micromachining; bulk silicon micromachining; lithography; electrodeposition and plastic molding; and electrodischarge machining (EDM). In recent years, electrostatic, magnetic, electromagnetic and thermal actuators, valves, gears and diaphragms of dimensions of hundred microns or less have been fabricated successfully. Sensors have been manufactured that …

Study Of The Effects Of Sodium And Absorber Microstructure For The Development Of Cuin1-Xgaxse2-Ysy Thin Film Solar Cell Using An Alternative Selenium Precursor, Vinaykumar Hadagali

Electronic Theses and Dissertations

Thin film solar cells have the potential to be an important contributor to the world energy demand in the 21st century. CuInGaSe2 thin film solar cells have achieved the highest efficiency among all the thin film technologies. A steady progress has been made in the research and development of CuInSe2 based thin film solar cells. However, there are many issues that need to be addressed for the development of CuInSe2 based thin films solar cells. High price of PV modules has been a biggest factor impeding the growth of photovoltaic modules for terrestrial application. This thesis tries to address the …

A Direct Compensator Profile Optimization Approach For Intensity Modulated Radiation Treatment Planning, Kevin Erhart

Electronic Theses and Dissertations

Radiation therapy accounts for treatment of over one million cancer patients each year in the United States alone, and its use will continue to grow rapidly in the coming years. Recently, many important advancements have been developed that greatly improve the outcomes and effectiveness of this treatment technique, the most notable being Intensity Modulated Radiation Therapy (IMRT). IMRT is a sophisticated treatment technique where the radiation dose is conformed to the tumor volume, thereby sparing nearby healthy tissue from excessive radiation dose. While IMRT is a valuable tool in the planning of radiation treatments, it is not without its difficulties. …

Singular Superposition/Boundary Element Method For Reconstruction Of Multi-Dimensional Heat Flux Distributions With Application To Film Cooling Holes, Mahmood Silieti, Eduardo Divo, Alain J. Kassab

Publications

A hybrid singularity superposition/boundary element-based inverse problem method for the reconstruction of multi-dimensional heat flux distributions is developed. Cauchy conditions are imposed at exposed surfaces that are readily reached for measurements while convective boundary conditions are unknown at surfaces that are not amenable to measurements such as the walls of the cooling holes. The purpose of the inverse analysis is to determine the heat flux distribution along cooling hole surfaces. This is accomplished in an iterative process by distributing a set of singularities (sinks) inside the physical boundaries of the cooling hole (usually along cooling hole centerline) with a given …

Fracture Toughness, Crack-Growth-Rate And Creep Studies Of Alloy 276, Joydepp Pal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Austenitic nickel-base Alloy 276 had been proposed to be a candidate structural material within the purview of the nuclear hydrogen initiative program. A mechanistic understanding of high temperature tensile deformation of this alloy has already been presented in an earlier investigation. The current investigation has been focused on the evaluation of crack-growth behavior, fracture toughness, stress-corrosion-cracking and creep deformation of this alloy as functions of different metallurgical and mechanical variables. The results of crack-growth study under cyclic loading indicate that this alloy exhibited greater cracking tendency with increasing temperature at a constant load ratio (R). However, the effect of temperature …

Research On The Transport And Deposition Of Nanoparticles In A Rotating Curved Pipe, Jianzhong Lin, Peifeng Lin, Huajun Chen

Mechanical Engineering Faculty Research

A finite-volume code and the SIMPLE scheme are used to study the transport and deposition of nanoparticles in a rotating curved pipe for different angular velocities, Dean numbers, and Schmidt numbers. The results show that when the Schmidt number is small, the nanoparticle distributions are mostly determined by the axial velocity. When the Schmidt number is many orders of magnitude larger than 1, the secondary flow will dominate the nanoparticle distribution. When the pipe corotates, the distribution of nanoparticle mass fraction is similar to that for the stationary case. There is a “hot spot” deposition region near the outside edge …

An H-Adaptive Finite-Element Technique For Constructing 3d Wind Fields, Darrell Pepper, Xiuling Wang

Mechanical Engineering Faculty Research

An h-adaptive, mass-consistent finite-element model (FEM) has been developed for constructing 3D wind fields over irregular terrain utilizing sparse meteorological tower data. The element size in the computational domain is dynamically controlled by an a posteriori error estimator based on the L2 norm. In the h-adaptive FEM algorithm, large element sizes are typically associated with smooth flow regions and small errors; small element sizes are attributed to fast-changing flow regions and large errors. The adaptive procedure employed in this model uses mesh refinement–unrefinement to satisfy error criteria. Results are presented for wind fields using sparse data obtained from two regions …

Harvesting Human Exercise Power At The Cal Poly Rec Center: Exercise Bike Power Generator Ii, Jared Rounsevell, Claire M. Shubert, Matthew Snitowsky, Andrew Wong

Mechanical Engineering

The overall goal of this project is to create a workable system to harvest the power generated on exercise bikes at the Cal Poly Rec Center so that the electricity produced can eventually be sent to the power grid. Our part of the project will focus on the mechanical harvesting of this power with the goal of using the product to run the Morningstar ProStar 12V 30 amp charge controller available from the 2007 project. Eventually, the power produced could be fed to the grid in the appropriate form. The finished result of this project should be marketable to exercise …

Transient Refrigerant Migration And Oil Distribution Of An R134a Automotive A/C System, Steffen Peuker, P. S. Hrnjak

Mechanical Engineering

Automotive fixed orifice tube (FOT) systems are especially prone to cycling losses due to their clutch cycling operation. Therefore, it is important to better understand the dynamics of the refrigerant and oil migration during transient events such as cycling and start-up. To measure the refrigerant mass and oil distribution of an automotive R134a FOT breadboard system, two ball valves around each component are added. By simultaneously closing the valves, the refrigerant and oil is trapped in different sections of the system and can be measured. The transient refrigerant migration during a stop-start transient as well as the refrigerant mass distribution …

A Novel Capacitance Sensor For Fireside Corrosion Measurement, Heng Ban, Zuoping Li

Mechanical and Aerospace Engineering Faculty Publications

Fireside corrosion in coal-fired power plants is a leading mechanism for boiler tube failures. Online monitoring of fireside corrosion can provide timely data to plant operators for mitigation implementation. This paper presents a novel sensor concept for measuring metal loss based on electrical capacitance. Laboratory-scale experiments demonstrated the feasibility of design, fabrication, and operation of the sensor. The fabrication of the prototype sensor involved sputtering deposition of a thin metal coating with varying thickness on a ceramic substrate. Corrosion metal loss resulted in a proportional decrease in electrical capacitance of the sensor. Laboratory experiments using a muffle furnace with an …

Vapor Generation In A Nanoparticle Liquid Suspension Using A Focused, Continuous Laser, R. A. Taylor, P. E. Phelan, Todd Otanicar, R. J. Adrian, P. S. Prasher

Mechanical Engineering Faculty Works

This letter discusses experimentation with optically induced phase change in nanoparticle liquid suspensions-commonly termed nanofluids. Four different types of nanofluids at five concentrations were exposed to a similar to 120 mW, 532 nm laser beam to determine the minimum laser flux needed to create vapor. Laser irradiance was varied between 0-770 W cm(-2). While the experiments were simple, they involved many complex, interrelated physical phenomena, including: subcooled boiling, thermal driven particle/bubble motion, nanoparticle radiative absorption/scattering, and nanoparticle clumping. Such phenomena could enable novel solar collectors in which the working fluid directly absorbs energy and undergoes phase change in a single …

Computational And Experimental Investigation Of The Flow Structure And Vortex Dynamics In The Wake Of A Formula 1 Tire, John Axerio, Gianluca Iaccarino, Emin Issakhanian, Chris Elkins, John Eaton

Mechanical Engineering Faculty Works

The flowfield around a 60% scale stationary Formula 1 tire in contact with the ground in a closed wind tunnel was examined experimentally in order to assess the accuracy of different turbulence modeling techniques. The results of steady RANS and Large Eddy Simulation (LES) were compared with PIV data, which was obtained within the same project. The far wake structure behind the wheel was dominated by two strong counter-rotating vortices. The locations of the vortex cores, extracted from the LES and PIV data as well as computed using different RANS models, showed that the LES predictions are closest to the …

Me-Em 2009 Annual Report, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering Annual Reports

Table of Contents

• Energy Systems
• Health Systems
• Faculty & Staff
• Students
• Alumni
• Resources
• Graduates
• Publications
• ME-EM Community

Explicit Finite Element Modeling Of Knee Mechanics During Simulated Dynamic Activities, Mark A. Baldwin

Electronic Theses and Dissertations

The natural knee is one of the most commonly injured joints in the body due to relatively high loads and motions that can lead to debilitating degenerative diseases such as osteoarthritis. Total knee arthroplasty is a clinically successful method for eliminating pain in the osteoarthritic knee, but is subject to complications that can affect patient satisfaction and long-term implant performance. The work presented in this dissertation is a demonstration of how anatomic three-dimensional (3D) computational knee models can be an effective alternative for investigating knee mechanics when compared to the cost and time prohibitive nature of in-vivo and in-vitro methods. …

Meso-Scale Heating Predictions For Weak Impact Of Granular Energetic Solids, Rohan Panchadhara

LSU Doctoral Dissertations

An explicit, two-dimensional, Lagrangian finite and discrete element technique is formulated and used to computationally characterize meso-scale fluctuations in thermomechanical fields induced by low pressure deformation waves propagating through particulate energetic solids. Emphasis is placed on characterizing the relative importance of plastic and friction work as meso-scale heating mechanisms which may cause bulk ignition of these materials and their dependence on piston speed (vp ~ 50-500 m/s). The numerical technique combines conservation principles with a plane strain, thermoelastic-viscoplastic constitutive theory to describe deformation within the material meso-structure. An energy consistent, penalty based, distributed potential force method, coupled to a penalty …

Modeling And Simulation Of High Pressure Composite Cylinders For Hydrogen Storage, Jianbing Hu

Doctoral Dissertations

"Composite hydrogen cylinders provide an efficient means of storage of hydrogen gas for modern hydrogen vehicles. Safety issues arising from the high gas pressure, temperature variation, fire attack, and fracture failures are the main concerns. The focus of this study is to develop a Finite Element (FE) model to predict the performance of composite cylinders subjected to extreme mechanical/thermal loadings and provide guidance for design optimization"--Abstract, page iv.

Fundamentals Of Friction Stir Spot Welding, Harsha Badarinarayan

Doctoral Dissertations

"The recent spike in energy costs has been a major contributor to propel the use of light weight alloys in the transportation industry. In particular, the automotive industry sees benefit in using light weight alloys to increase fuel efficiency and enhance performance. In this context, light weight design by replacing steel with Al and/or Mg alloys have been considered as promising initiatives. The joining of structures made of light weight alloys is therefore very important and calls for more attention. Friction Stir Spot Welding (FSSW) is an evolving technique that offers several advantages over conventional joining processes.

The fundamentals aspects …

Information Archival And Reuse: Drawing Conclusions From The Past, Matt R. Bohm

Doctoral Dissertations

"Over the last few decades design researchers have put forward theories and proposed methodologies that increase the chance that a design team will reliably arrive at the optimal solution to a given design problem. Studies, however, bear out that theories and methodologies alone will not guarantee an optimal or even good design solution. Instead, a breadth of knowledge across multiple engineering domains and the time and tools to thoroughly evaluate the design space are as important as any prescriptive design method. This work presents a set of underlying engineering technologies to define, archive and reuse product design knowledge to provide …

Large Eddy Simulation Of Turbulent Premixed Combustion In Gas Turbines, Ashoke De

LSU Doctoral Dissertations

An artificially Thickened Flame (TF) approach based on LES framework is used to model the turbulent premixed combustion in gas turbine combustors. A number of variants of the Thickened Flame approach including a modified version of TF model have been studied in details. In the TF model, the flame front is artificially thickened to resolve on LES computational grid. With this approach, reaction rate modeling does not require any ad-hoc closure assumptions. However, suitable modifications have to be made to compensate for flame thickening. To verify the predictive capability of the models, a stoichiometric methane-air flame on Bunsen burner type …

Multiphase Flows In Polymer Microfluidic Systems, Namwon Kim

LSU Doctoral Dissertations

Continuous delivery of segmented reagents using pressure-driven multiphase flow in microchannels is a promising technology for high throughput microfluidic bioassays. Separation and encapsulation of the target reagents with another inert fluid provide many advantages over single phase flow in microfluidic applications of biotechnology. In order to achieve these advantages and control these multiphase flows, it is necessary to understand their generation and transport characteristics as influenced by geometrical miniaturization, channel wall properties, the effects of surfactants and operating conditions. For gas-liquid two-phase flow, dry air and deionized water were driven into hot embossed PMMA microchannels with 200 μm square test …

Providing Academic Leadership Through The Role Of Senior Lecturer 1 (Teaching) Using The Theme Of 'Sustainable Energy' As An Example, Jim Mcgovern

Articles

An academic leader should lead in their particular area and should love what they are doing. An example of leadership in the area of 'sustainable energy use' is presented that involves leading through identifying and participating in the development of emerging technologies. Excellent academic leadership can be provided by a Senior Lecturer through active research, incorporating the latest developments in student-centred learning in their work and providing example and encouragement for colleagues and learners.

The Effect Of Air Preheating In A Biomass Cfb Gasifier Using Aspen Plus Simulation, Wayne Doherty, Anthony Reynolds, David Kennedy

Articles

In the context of climate change, increasing efficiency and energy security, biomass gasification is likely to play an important role in energy production. Atmospheric circulating fluidised bed (CFB) technology was selected for the current study. The primary objective of this research is to develop a computer simulation model of a CFB biomass gasifier that can accurately predict gasifier performance under various operating conditions. An original model was developed using ASPEN Plus (Advanced System for Process ENgineering Plus). The model is based on Gibbs free energy minimisation. The restricted equilibrium method was used to calibrate the model against experimental data. This …