Mechanical Engineering Commons^™

Numerical Modeling Of The Dynamic Response Of A Multi-Bilinear-Spring Support System, Trey D. Gilliam

University of Kentucky Master's Theses

The Alpha Magnetic Spectrometer is an International Space Station Experiment that features a unique nonlinear support system with no previous flight heritage. The experiment consists of multiple straps with piecewise-linear stiffness curves that support a cryogenic magnet in three-dimensional space inside of a vacuum chamber. The stiffness curves for each strap are essentially bilinear and switch between two distinct slopes at a specified displacement. This highly nonlinear support system poses many questions in regards to feasible computational methods of analysis and possible response behavior. This thesis develops a numerical model for a multi-bilinear-spring support system motivated by the Alpha Magnetic …

Interfacial Thermal Conductivity Using Multiwall Carbon Nanotubes, Carissa Don Russell

University of Kentucky Master's Theses

Shrinking volume, coupled with higher performance, microprocessors and integrated circuits have led to serious heat dissipation issues. In an effort to mitigate the excessive amounts of waste heat and ensure electronic survivability, heat sinks and spreaders are incorporated into heat generating device structures. This inevitability creates a thermal pathway through an interface. Thermal interfaces can possess serious thermal resistances for heat conduction. The introduction of a thermal interface material (TIM) can drastically increase the thermal performance of the component. Exceptional thermal properties of multiwall carbon nanotubes (MWCNTs) have spurred interest in their use as TIMs. MWCNTs inherently grow in vertically-oriented, …

Characterization Of Ni-Rich Nitihf Based High Temperature Shape Memory Alloys, Gurdish S. Ded

University of Kentucky Master's Theses

Among the potential high temperature shape memory alloys, due to its low cost, medium ductility and high work output NiTiHf seems to be the most promising HTSMA for a wide range of applications in the 100-250ºC. A detailed investigation into the shape memory properties and transformation behavior for the Ni-rich HTSMA with the compositions of Ni_45.3Cu₅Ti_29.7Hf₂₀, Ni_50.3Ti_29.7Hf₂₀ and Ni_45.3Pd₅Ti_29.7Hf₂₀ was carried out. It is possible to form Ni-rich precipitates in Ni-rich NiTiHf alloys and tailor the TTs by heat treatments …

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

Nanofluid-Based Direct Absorption Solar Collector, Todd Otanicar, P. E. Phelan, R. S. Prasher, G. Rosengarten, R. A. Taylor

Mechanical Engineering Faculty Works

Solar energy is one of the best sources of renewable energy with minimal environmental impact. Direct absorption solar collectors have been proposed for a variety of applications such as water heating; however the efficiency of these collectors is limited by the absorption properties of the working fluid, which is very poor for typical fluids used in solar collectors. It has been shown that mixing nanoparticles in a liquid (nanofluid) has a dramatic effect on the liquid thermophysical properties such as thermal conductivity. Nanoparticles also offer the potential of improving the radiative properties of liquids, leading to an increase in the …

Nonparametric Estimation Of Derivatives With Applications, Benjamin Hall

University of Kentucky Doctoral Dissertations

We review several nonparametric regression techniques and discuss their various strengths and weaknesses with an emphasis on derivative estimation and confidence band creation. We develop a generalized C(p) criterion for tuning parameter selection when interest lies in estimating one or more derivatives and the estimator is both linear in the observed responses and self-consistent. We propose a method for constructing simultaneous confidence bands for the mean response and one or more derivatives, where simultaneous now refers both to values of the covariate and to all derivatives under consideration. In addition we generalize the simultaneous confidence bands to account for heteroscedastic …

An Mpi-Cuda Implementation For Massively Parallel Incompressible Flow Computations On Multi-Gpu Clusters, Dana A. Jacobsen, Julien C. Thibault, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Modern graphics processing units (GPUs) with many-core architectures have emerged as general-purpose parallel computing platforms that can accelerate simulation science applications tremendously. While multi-GPU workstations with several TeraFLOPS of peak computing power are available to accelerate computational problems, larger problems require even more resources. Conventional clusters of central processing units (CPU) are now being augmented with multiple GPUs in each compute-node to tackle large problems. The heterogeneous architecture of a multi-GPU cluster with a deep memory hierarchy creates unique challenges in developing scalable and efficient simulation codes. In this study, we pursue mixed MPI-CUDA implementations and investigate three strategies to …

Development Of A Multi-Material Stereolithography System, Ho-Chan Kim, Jae-Won Choi, Ryan B. Wicker

Mechanical Engineering Faculty Research

Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats …

High School Bridge Program: A Multidisciplinary Stem Research Program, Jiang Zhe, Dennis Doverspike, Julie Zhao, Paul C. Lam, Craig C. Menzemer

Mechanical Engineering Faculty Research

A Science, Technology, Engineering and Math (STEM) summer Bridge Program was developed for high school students. The program was designed to encourage students to consider choosing an engineering major in college and to explore STEM as a future career. This was accomplished through a 10-week program involving multidisciplinary research activities. The participants in the program included 33 high school students. Among former participants in position to make a choice in terms of attending college, 100% had chosen to continue on in college, and 86% had chosen to major in a STEM area. The results indicated that that the program had …

Formula Sae Impact Attenuator Testing, Chad Abrahamson, Bill Bruns, Joseph Hammond, Josh Lutter

The Journal of Undergraduate Research

The purpose of this paper is to validate the impact attenuator designed by SDSU Formula SAE team according to 2010 Formula SAE rules. The impact attenuator is made of Plascore PCGA-XR1-5.2-1/4-P-3003 aluminum honeycomb that is pre-crushed to 245 psi. The test was dynamically performed using a 661 lb mass dropped 8.3 ft onto the material sample at 23 ft/sec, and data was measured with an Olympus i-SPEED 3 high speed camera. The impact attenuator must have an average deceleration equal to or less than 20 G’s and a peak deceleration equal to or less than 40 G’s. Two specimens were …

Skewed Bridge Behaviors: Experimental, Analytical, And Numerical Analysis, Bang-Jo Chun

Wayne State University Dissertations

In the US, nearly 33.5% of highway bridges are skewed. In the past, these skewed bridges have been analyzed as straight bridges. Nevertheless, there exists an extensive literature indicating the mechanical behavior of skewed bridges being quite different from their straight counterparts. In this thesis, to better understand the behavior of skewed bridges, experimental, numerical, and analytical researches have been conducted. The analytical method proposed here is the first of its kind in the skewed bridge research, and is expected to aid the bridge engineers with their design.

First, a three dimensional finite element analysis (FEA) model was developed and …

A Novel Image Processing Platform Development For Preprocessing Images With Two-Phase Microstructures Containing Isolated Particles, Yuxiu Zhang

Wayne State University Theses

A novel image processing platform is developed in this thesis for pre-processing the images of two-phase microstructures containing isolated particles based on Matlab®. The two phases in this work represent martensite particles and ferrite matrix in Dual Phase steels that are developed for lightweight automotive body structures. An automated image processing tool is useful for obtaining statistical microstructure characteristics, important for better understanding material's deformation and fracture behavior. However, a generalized commercial software can not automatically realize the microstructural features of special interest, and a user-specified pre-processing tool is needed.

This platform utilizes the Matlab® GUI technique, Matlab image processing …

Effect Of Alternative Fuels On Aftertreatment Device, Bunpreet Singh

Wayne State University Theses

EFFECT OF ALTERNATIVE FUELS ON THE AFTERTREATMENT DEVICE.

by

BUNPREET SINGH

Dec 2010

Advisor: Dr. Dinu Taraza

Major: Mechanical Engineering

Degree: Master of Science

There is no doubt that globally, alternative fuels have attained the center of attention in order to reduce the dependency on fossil fuels. A lot of research has been conducted on the alternative fuels in the automotive industry pertaining to the sustainability, engine performance and the emission characteristics.

The focus of this study is to investigate the effect of alternative fuels (JP8, Soy-based B20, and S8) on the aftertreatment device. Different fuel properties (both physical and …

Adhesion And Wear Behavior Of Nanostructured Titanium Oxide Thin Films

A.S. Md Abdul Haseeb

No abstract provided.

Investigations On Tio2 And Ag Based Single And Multilayer Films For Window Glazings

A.S. Md Abdul Haseeb

In this investigation, TiO2 and Ag based single and multilayer-films were deposited on microscope glass slides with varying individual layer thicknesses by radio-frequency reactive magnetron sputtering. Prior to multilayer development, single layers of Ag and TiO2 were deposited and characterized. All the films were prepared at an elevated pressure of 3 Pa at room temperature. It was found that single layer of TiO2 showed anatase polycrystalline structure. It also exhibited high visible transmittance of above 80% and higher refractive index of 2.31 at a wavelength of 550 nm. The indirect optical band gap of the TiO2 films was estimated as …

Influence Of Substrate Temperatures On Structural, Morphological And Optical Properties Of Rf-Sputtered Anatase Tio 2 Films

A.S. Md Abdul Haseeb

In this investigation, TiO 2 thin films were deposited on glass substrates at varying substrate temperatures from room temperature to 300 °C by radio-frequency (RF) magnetron sputtering at an elevated sputtering pressure of 3 Pa. As-deposited TiO 2 films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), field emission Auger electron microscopy (FEAES), and UV-visible-NIR spectrophotometry. The XRD results reveal that all the as-deposited films possessing the anatase structure and crystallinity of TiO 2 films appears to deteriorate slightly at higher substrate temperatures. The crystallite size of the as-deposited films at different substrate temperatures …

Selective Area Rare-Earth Doping Of Planar Glass Samples For Monolithic Integration Of Optically Passive And Active Waveguides

A.S. Md Abdul Haseeb

Successful demonstration of selective area doping of planar glass samples for monolithic integration of optically passive and active devices on a single chip is presented. Salt solution of erbium was delivered onto pre-sintered germano-silicate samples via a syringe. The samples were then consolidated to form dense glass layers containing regions doped with rare earth. Erbium tri-chloride solution, 0.1 M, was used during the solution doping phase, with the resulting erbium atomic percentage ranging from more than 0.1-0.4%, increasing linearly with the number of drips applied. © 2008 Elsevier GmbH. All rights reserved.

Fractionation And Characterization Of Oil Palm (Elaeis Guineensis) As Treated By Supercritical Water, Mahendra Varman Munusamy M.Varman, H. Miyafuji, S. Saka

Mahendra Varman Munusamy (M. Varman)

In order to investigate the potential for efficient utilization of oil palm (Elaeis guineensis), supercritical water treatment (at 380°C and 100 MPa for 8 s) was applied to fractionate extractives-free samples into water-soluble portion and water-insoluble portion. The water-insoluble portion was further fractionated into methanol-soluble portion and methanol-insoluble residue. Samples were prepared from various parts of oil palm, i.e., trunks, fronds, mesocarp fibers, shells, empty fruit bunches, and kernel cake. These fractionated products were then characterized analytically. The water-soluble and methanol-soluble portions were determined to be mainly composed of carbohydrate-derived products and lignin-derived products, respectively. The methanol-insoluble residue was mainly …

Lai - Introduction To Continuum Mechanics نسخه اصلی کتاب مکانیک محیط پیوسته ویرایش چهارم, Dr Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.