Engineering Commons^™

The Thermal Characteristics Of Liquid-Heat-Spreader, Sang Muk Kwark

Mechanical and Aerospace Engineering Theses - Archive

The present study is an experimental research of a liquid-heat-spreader (LHS) with saturated water at ~2.29 psia. A LHS, indirect liquid cooling module, was successfully fabricated using thin copper blocks and copper tubes using solder. Three types of LHS, Flat-type, L-type, and T-type, were developed for different orientations and were compared with solid metal blocks such as aluminum and copper. The Flat-type LHS, 100 (W) × 254 (L) × 3 (T) mm3, was designed for vertical orientation. It showed a remarkable thermal performance by dissipating heat flux of 119 W/cm2 with below 100? chip temperature at the typical condition. The …

A Compliant Contact-Aided Revolute Joint, Jessie R. Cannon, Larry L. Howell

Faculty Publications

This paper presents the compliant contact-aided revolute (CCAR) joint, a planar mechanism capable of performing the functions of a bearing and a spring. The pseudo-rigid-body model is used to predict the behavior of the CCAR joint, and this model is validated through the use of finite element analysis and prototype testing. The CCAR joint is shown to have high maximum rotation and lateral stiffness. A case study is presented, and manufacturing considerations are discussed for the macro, meso, and micro scales.

Measurement Of Interfacial Shear Mechanical Properties In Thermal Barrier Coating Systems By A Barb Pullout Method, S. Q. Guo, D. R. Mumm, Anette M. Karlsson, Y. Kagawa

Mechanical Engineering Faculty Publications

A test technique has been developed to facilitate evaluation of the fracture characteristics of coatings and interfaces in thermal barrier coating (TBC) systems. The methodology has particular application in analyzing delamination crack growth, where crack propagation occurs under predominantly mode II loading. The technique has been demonstrated by quantitatively measuring the effective delamination fracture resistance of an electron-beam physical vapor deposition TBC.

Energy Efficient Transportation For Florida, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Nearly 30% of energy used in Florida is consumed by our 13 million personal automobiles. Annual gasoline consumption in Florida is about 7.5 billion gallons. Florida also has more registered cars per capita than any other state in the U.S. - nearly one car for each person. The average Florida automobile is driven over 10,000 miles a year burning about 550 gallons of gasoline and costing its owner about $1,500 in fuel costs alone (not to mention payments, insurance, service, repairs, tires, tags, license etc.). Based on a comprehensive analysis, total automobile operating costs average over $850 per month.

Evaluation Of Cost Effective Sensor Combinations For A Vehicle Precrash Detection System, John Carlin, Charles Birdsong, Peter Schuster, William Thompson, Daniel Kawano

Mechanical Engineering

The future of vehicle safety will benefit greatly from precrash detection -the ability of a motor vehicle to predict the occurrence of an accident before it occurs. There are many different sensor technologies currently available for pre-crash detection. However no single sensor technology has demonstrated enough information gathering capability within the cost constraints of vehicle manufacturers to be used as a stand alone device. A proposed solution consists of combining information from multiple sensors in an intelligent computer algorithm to determine accurate precrash information. In this paper, a list of sensors currently available on motor vehicles and those that show …

Elasticity Of Planar Fiber Networks, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

A micromechanics model is proposed for the elasticity of planar fiber networks (FNs). The FN is created by random deposition of linearly elastic straight rods within a region. The rods are bonded rigidly at contacts. Under external in-plane loading, the FN deformation consists of fiber bending, elongation, and contraction. An effective constitutive relation for fiber network is developed by averaging the strain energy dissipated by all possible fiber deformations in all directions. Numerical calculations are performed to analyze the effects of fiber aspect ratio and fiber concentration on the effective stiffness of the planar random FN. Finite element analysis (FEA) …

A Compliant Contact-Aided Revolute Joint, Jessie R. Cannon, Larry L. Howell

Faculty Publications

This paper presents the compliant contact-aided revolute (CCAR) joint, a planar mechanism capable of performing the functions of a bearing and a spring. The pseudo-rigid-body model is used to predict the behavior of the CCAR joint, and this model is validated through the use of finite element analysis and prototype testing. The CCAR joint is shown to have high maximum rotation and lateral stiffness. A case study is presented, and manufacturing considerations are discussed for the macro, meso, and micro scales.

High Temperature Heat Exchanger Project: Quarterly Progress Report July 1, 2005 Through September 30, 2005, Anthony Hechanova

Publications (NSTD)

Quarterly Collaboration Meeting. The University of California, Berkeley, hosted a UNLVRF HTHX Project quarterly meeting on September 12. The purpose of the meeting was to promote collaboration and communication among the UNLV Research Foundation partners. Collaborators discussed their research program plan and provided an update on their progress. The next meeting will be in December in Las Vegas, NV hosted by UNLV.

A Fe-Fd Hybrid Scheme For Solving Parabolic Two-Step Micro Heat Transport Equations In Irregularly Shaped Three Dimensional Double -Layered Thin Films Exposed To Ultrashort -Pulse Lasers, Brian R. Barron

Doctoral Dissertations

Multi-layer thin films are important components in many micro-electronic devices. These films are often used when a single film layer is insufficient to meet devices specifications. The continued reduction in component size has the side effect of increasing the thermal stress on these films and consequently the devices they comprise. Understanding the transfer of heat-energy at the micro-scale is important for thermal processing using a pulse-laser. Often, micro-voids may be found in processed devices. This is due to thermal expansion. Such defects may cause an amplification of neighboring defects resulting in severe damage and consequently the failure of the device. …

Association Between Lower Extremity Posture At Contact And Peak Knee Valgus Moment During Sidestepping: Implications For Acl Injury, Scott G. Mclean, Xuemei M. Huang, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Background. Knee valgus load during sports movement is viewed as an important predictor of non-contact anterior cruciate ligament injury risk, particularly in females. Formulating movement strategies that can reduce valgus loading during these movements therefore appears pertinent to reducing anterior cruciate ligament injury rates. With this in mind, the current study examined the relationship between peak valgus moment and lower extremity postures at impact during a sidestep cutting task.

Methods. Ten male and ten female NCAA athletes had initial contact three-dimensional hip, knee and ankle angles and subsequent knee valgus moment quantified during the execution of (n=10 trials) …

Letter To The Editor, Scott G. Mclean, Jack T. Andrish, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

No abstract provided.

High-Resolution Methods For Measuring The Thermal Expansion Coefficient Of Aerospace Materials, G. Wallace, W. Speer, J. Ogren, Omar S. Es-Said

Mechanical Engineering Faculty Works

Accurately predicting the coefficient of thermal expansion for many aerospace components is critical to ensure proper functionality on orbit where the temperature gradient across a spacecraft can vary from +300 degrees F to -450 degrees F. Under these conditions, the linear approximations generated by theoretical equations no longer hold true, and experimental methods are needed. Although several methods exist for measuring the coefficient of thermal expansion of materials, laser interferometry yields high-resolution results, and the technique is widely accepted in the scientific community.

2005 (Fall) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the fall of 2005.

Damage-Induced Modeling Of Asphalt Mixtures Through Computational Micromechanics And Cohesive Zone Fracture, Yong-Rak Kim, D. H. Allen, D. N. Little

Department of Engineering Mechanics: Faculty Publications

This paper presents a computational micromechanics modeling approach to predict damage-induced mechanical response of asphalt mixtures. Heterogeneous geometric characteristics and inelastic mechanical behavior were taken into account by introducing finite element modeling techniques and a viscoelastic material model. The modeling also includes interface fracture to represent crack growth and damage evolution. The interface fracture is modeled by using a micromechanical nonlinear viscoelastic cohesive-zone constitutive relation. Fundamental material properties and fracture characteristics were measured from simple laboratory tests and then incorporated into the model to predict rate-dependent viscoelastic damage behavior of the asphalt mixture. Simulation results demonstrate that each model parameter …

Design Of Multistep Aging Treatments Of 2099 (C458) Al-Li Alloy, M. Romios, R. Tiraschi, C. Parrish, H. W. Babel, J. Ogren, Omar S. Es-Said

Mechanical Engineering Faculty Works

Multistep artificial aging treatments coupled with various natural aging times for aluminum lithium 2099 alloy (previously called C458) are discussed to obtain mechanical tensile properties in the T6 condition that match those in the T861 condition, having a yield strength in the range of 414-490 MPa (60-71 ksi), an ultimate strength in the range of 496-538 MPa (72-78 ksi), and 10-13% elongation. Yield and ultimate tensile strengths from 90-100% of the strength of the as-received material (in the T861 condition) were obtained. The highest tensile strengths were consistently obtained with two-step, low-to-high temperature artificial aging treatments consisting of a first …

Repeatable Nanostructures In Dielectrics By Femtosecond Laser Pulse Trains, Lan Jiang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the plasma model recent developed by the authors, this study predicts the existence of a constant ablation-depth zone with respect to fluence in femtosecond laser ablation of dielectrics, which has also been observed experimentally. It is found that the value of the constant ablation depth is significantly decreased by the pulse train technology. Repeatable nanostructures can be achieved with the parameters in the constant ablation-depth zone of a femtosecond pulse train, even when the laser system is subject to fluctuations in fluences.

Validation Of Finite Element Beam Models, Pavan R. Madhineni

Mechanical & Aerospace Engineering Theses & Dissertations

Finite Element (FE) methods these days are becoming very popular to predict the responses of structures in industries, such as the aerospace and automobile industries. When there is a new design or modification of an existing design, the product must be tested to fulfill the criterion projected by the industry or external agencies before it can be launched. The product must be checked for each and every aspect, and every minute detail of each of the external forces. Hence, it becomes very important to carry out the model validation on the product.

This thesis describes validation of finite element (FE) …

Shape And Size Sensitivity Analysis Of Geometrically Nonlinear Laminated Composite Plates, Nitin R. Mane

Mechanical & Aerospace Engineering Theses & Dissertations

Since major applications of composite laminates involve large deformation, the nonlinear strain-displacement relation in the Von Karman sense has been incorporated here with the first order shear deformation to study bending analysis of composite laminated panels. The finite element model constructed here is an extension of the MIN3 element which is a displacement based element developed by Hughes and Tessler. The element avoids shear locking in the thin bending regime and achieves computational efficiency. The resultant nonlinear matrix equation is solved for analysis of composite panels by using the Newton-Raphson iterative method. Based upon the nonlinear matrix equation, the shape …

Complexity Measure Of A Product Or Process By Application Of Fuzzy Multi-Attribute Utility Theory, Shrikant Chandrakant Nagpure

Mechanical & Aerospace Engineering Theses & Dissertations

During the early phases of design, the development cost of complex products or systems is very difficult to obtain because of the uncertainties related to their work breakdown structures and the wide choice of manufacturing technologies with no historical data specific to these products. This thesis presents a method to derive a complexity index to capture the non-additive property and inherent uncertainty, i.e. fuzziness, of the technologies that could be used for complex objects. This complexity index can then be used as a cost index for comparing various candidate manufacturing processes.

Macros are written in Microsoft Excel to establish a …

Computational Analysis And Validation Of The Hans Head And Neck Support, Kapil Tyagi

Mechanical & Aerospace Engineering Theses & Dissertations

One of the major causes of racing fatalities is basilar skull fracture from excessive head motions and neck loading in a frontal impact. There are many head/neck restraints available in the market but HANS head and neck support has proved to be the most efficient one in sled testing. This paper evaluates and compares the performance of the HANS device in MAthematical DYnamic MOdel (MADYMO) software with the sled testing. The tests were conducted for the frontal impact motions, with a crash pulse of 45 G's.

The goal of the tests was to evaluate the performance of HANS without the …

Support For A Delivery Train Based Material Handling Mechanism, Sai P. Boyedapu

Electrical & Computer Engineering Theses & Dissertations

Modeling a delivery train system is more challenging than traditional forklift systems as the delivery train model consists of a tugger, cart and a controller that combine to deliver materials within a manufacturing plant. Also, the decision logic for selection of carts and tuggers, joining of loads to particular delivery trains is more complicated than forklift systems. Simulation software such as Arena, Automod and Flexsim do not provide direct support for modeling delivery train systems.

In this thesis, an object-oriented, platform and language independent model of a delivery train was designed. The model was then implemented as an extension to …

Gauss-Hermite Integration For Reliability Calculation And Sensitivity Analysis, Nilesh K. Borade

Mechanical & Aerospace Engineering Theses & Dissertations

In the real world, many applications are subjected to uncertainty. A simple illustration would be a structure like a bridge where magnitude and the speed of the loads acting on it are continuously changing. Therefore it becomes essential to study this stochastic or random nature. The thrust of this research is to develop an efficient reliability and sensitivity technique based on stochastic response surfaces (polynomial chaos expansions) constructed using Gauss-Hermite integration. The focus is on calculating the uncertainty propagation using less number of function evaluations since the stochastic response surface needs to be reconstructed at each design cycle. Using the …

An Analysis Of A Finite Element Human Brain In Low Speed Rear Impact Automobile Collision Comparison, Model Development And Study Using Tno Rear Impact Dummy, Mangesh S. Kadam

Mechanical & Aerospace Engineering Theses & Dissertations

According to the National Safety Council, rear-end collisions are the most common types of collisions with approximately two and a half million cases reported every year. Crash tests indicate a change of vehicle velocity of 4km/h (2.5 mph) may produce occupant symptoms. Vehicle damage may not occur until 14-15km/h (8.7 mph) (Davis CG, 1998). Occupants, in rear-end vehicle impacts sustain a motion associated with whiplash, where the head snaps backwards quickly, resulting in linear and/or angular acceleration forces acting on the brain. This angular motion tends to subject the brain to shear deformations from rapid rotation. This study is a …

Conjugate Gradient Method For Solving System Of Nonlinear Equations, Abhijit Prakash Honrao

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, the conjugate gradient method will be extended to solve symmetric and non-symmetric nonlinear equations. Several variations of the conjugate gradient method are introduced and investigated. To extend the conjugate gradient method for nonlinear problems, there are four methods discussed; the pre-conditioning conjugate gradient method, the pre-conditioning conjugate gradient method for better initial guess, the fixed point conjugate gradient method and the fixed point conjugate gradient method for better initial guess. The four methods are discussed in detail and tested on various numerical examples. The linear numerical examples include a two dimensional structural frame problem, a Hilbert matrix …

Programmable Multi-Dose Intransal Drug Delivery Device, Daniel Wermeling, Ryan Vallance, Aravind Balasubramanian, Bruce L. Walcott, John Alan Main, James E. Lumpp Jr.

Mechanical Engineering Faculty Patents

An apparatus and method for the self-administration of a plurality of doses of an intranasal liquid pharmaceutical composition, including opioid analgesics, that includes a drug delivery device containing a plurality of sealed vials, each vial containing a predetermined volume of the pharmaceutical composition, a pump assembly for conveying the liquid pharmaceutical composition from the interior of the vial and discharging it as a nasal spray in response to manual activation by the patient, and programmable means for sequentially advancing a vial to the ready position after passage of a prescribed time interval following the last activation of the delivery device.

Compliant Ortho-Planar Spring Behavior Under Complex Loads, Nathan Oliver Rasmussen

Theses and Dissertations

This thesis presents research on the feasibility of applying compliant-ortho-planar springs (COPS) to rotational applications. The primary motivation of this research is the application of COPS to a continuously variable transmission (CVT). The design space limitations, loading conditions, stresses, stress concentrations, and limitations of current design tools, such as pseudo-rigid-body models (PRBM) for COPS, are discussed. A new 3D PRBM is presented along with a discussion on the possible applications of such to a rotating COPS. Stress stiffening and lateral stability are two major phenomena occurring in a rotating COPS. Both phenomena are a direct result of the inertial loads …

A Study Of Non-Linear Vibrational Behavior Of Cracked Structures By The Finite Element Method, Tzuo-Liang Luo, James Shih-Shyn Wu, Jui-Pin Hung

Journal of Marine Science and Technology–Taiwan

Numerical and experimental investigations provide a link to the location and size of cracks caused by natural vibrations. Cracks may generally result in the variation of structural stiffness and hence enable structures to vibrate nonlinearly. In order to understand the vibrational behavior of crack structures accurately, the study proposes a general and efficient algorithm based on the finite element assumptions and the bilinear vibrational theory. All formulae are derived from the time domain properly and may apply to the overall non-linear motion cycle completely. The contact effect is also considered by introducing the degree of penetration on the cracked surface. …

Experimental Measurements Of Longitudinal Load Distributions On Friction Stir Weld Pin Tools, Aaron L. Stahl

Theses and Dissertations

The longitudinal forces generated from the Friction Stir Welding process are substantial. An understanding of these forces is critical to proper tool design. This study describes a technique to measure the longitudinal force distribution on a friction stir weld pin tool. Total longitudinal forces were recorded on a dynamometer while welding 6061 aluminum with non-threaded pins that varied in length and diameter. A model was developed that characterizes pin force as a function of pin length and diameter. Results suggest that force generally increases with pin length, while forces remain relatively constant with pin diameter. Unexpected force variation was found …

2005 Fall Engr333 Project Assignment, Matthew K. Heun

ENGR 333

In the Fall 2005 semester, I challenged the ENGR333 students to “develop realistic designs for the wellness center HVAC system and upgraded physical plant infrastructure.”

Customer

The customer for this project was Calvin’s VP for finance Henry DeVries.

Optimization Of The Fuzzy Logic Controller For An Autonomous Uav, Jon C. Ervin, Sema E. Alptekin, Dianne J. Deturris

Industrial and Manufacturing Engineering

In this paper, we describe the optimization of membership functions in an application employing a hierarchical Fuzzy Logic Controller. The size of the rule base is made manageable by using a unique formulation, known as Combs method, to help control the problem of ‘exponential rule expansion’. The optimization is performed using a steady state genetic algorithm with a dynamic fitness function. The controller being developed is designed to fly a small, autonomous parafoil, suitable for short-range reconnaissance and land survey applications. The optimization process is performed in the Matlab/Simulink software environment and incorporates fuzzy logic modules developed in the Matlab …