Engineering Commons^™

Trailer Mounted Bursting Energy Absorption System, John D. Reid, John R. Rohde, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A portable crash attenuation System having a trailer frame and an energy absorption mechanism attached thereto. The absorption mechanism has a first Stage pivotably connected to a Second Stage and the Second Stage is pivotably connected to the frame. By pivoting the Stages about hinges the attenuation System may be folded from an extended, deployed position or mode to a shortened transit mode for easy relocation of the entire attenuation System.

Enhanced Practical Photosynthetic Co₂ Mitigation, David J. Bayless, Morgan Lefay Vis-Chiasson, Gregory G. Kremer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This process is unique in photosynthetic carbon sequestration. An on-site biological sequestration system directly decreases the concentration of carbon-containing compounds in the emissions of fossil generation units. In this process, photosynthetic microbes are attached to a growth surface arranged in a containment chamber that is lit by solar photons. A harvesting system ensures maximum organism growth and rate of CO₂ uptake. Soluble carbon and nitrogen concentrations delivered to the cyanobacteria are enhanced, further increasing growth rate and carbon utilization.

Dec 2003, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Introductions Curator's Report Treasurer's Report

Processes For Nanomachining Using Carbon Nanotubes, Robert Ryan Vallance, Apparao M. Rao, M. Pinar Mengüç

Mechanical Engineering Faculty Patents

Novel methods and devices for nanomachining a desired pattern on a surface of a conductive workpiece are disclosed. In one aspect, the method comprises using an electron beam emitted from one or more nanotubes to evaporate nanoscale quantities of material from the workpiece surface. The surface of the workpiece to be machined may be excited to a threshold energy to reduce the amount of power required to be emitted by the nanotube. In another aspect, a device is described for nanomachining a desired pattern on a surface of a conductive workpiece, comprising a vessel capable of sustaining a vacuum, a …

Simulated Properties Of Kagomé And Tetragonal Truss Core Panels, S. Hyun, Anette M. Karlsson, S. Torquato, A. G. Evans

Mechanical Engineering Faculty Publications

The finite element method has been used to simulate the properties of panels with Kagomé and tetragonal cores under compressive and shear loading. The simulation has been performed for two different materials: a Cu-alloy with extensive strain hardening and an Al-alloy with minimal hardening. It is shown that the Kagomé core is more resistant to plastic buckling than the tetragonal core under both compression and shear. One consequence is that the Kagomé structure has the greater load capacity and a deferred susceptibility to softening. Another is that the Kagomé core is isotropic in shear: contrasting with the soft orientations exhibited …

Development And Validation Of A 3-D Model To Predict Knee Joint Loading During Dynamic Movement, Scott G. Mclean, Anne Su, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The purpose of this study was to develop a subject-specific 3-D model of the lower
extremity to predict neuromuscular control effects on 3-D knee joint loading during movements that can potentially cause injury to the anterior cruciate ligament (ACL) in the knee. The simulation consisted of a forward dynamic 3-D musculoskeletal model of the lower extremity, scaled to represent a specific subject. Inputs of the model were the initial position and velocity of the skeletal elements, and the muscle stimulation patterns. Outputs of the model were movement and ground reaction forces, as well as resultant 3-D forces and moments acting …

Multiple Uav Cooperative Search Under Collision Avoidance And Limited Range Communication Constraints, Randal W. Beard, Timothy W. Mclain

Faculty Publications

This paper focuses on the problem of cooperatively searching, using a team of unmanned air vehicles (UAVs), an area of interest that contains regions of opportunity and regions of potential hazard. The objective of the UAV team is to visit as many opportunities as possible, while avoiding as many hazards as possible. To enable cooperation, the UAVs are constrained to stay within communication range of one another. Collision avoidance is also required. Algorithms for team-optimal and individually-optimal/team-suboptimal solutions are developed and their computational complexity compared. Simulation results demonstrating the feasibility of the cooperative search algorithms are presented.

Dynamic Modeling Of Compliant Constant-Force Compression Mechanisms, Cameron Boyle, Larry L. Howell, Spencer P. Magleby, Mark S. Evans

Faculty Publications

A mathematical dynamic model is derived for compliant, constant-force compression-mechanisms, based on the pseudo-rigid-body model simplification of the device. The compliant constant-force compression mechanism (CFCM) is a slider mechanism incorporating large-deflection beams, which outputs near-constant-force across the range of its designed deflection. The equation of motion is successfully calibrated with empirical data from five separate mechanisms, comprising two basic configurations of CFCMs. The dynamic equation is derived from a generalized pseudo-rigid-body model. This allows every configuration to be represented by the same model, so a separate treatment is not required for each configuration. An unexpected dynamic trait of the constant-force …

Why Toyota And Honda Topped The 2002 J.D. Power Quality Study, Susan Lightle, Kenneth Yale Rosenzweig, John Talbott

Accounting Faculty Publications

Toyota again topped the annual J. D. Power and Associates quality study released in late May of 2002. Toyota scored the highest mark ever with l 07 defects per l 00 vehicles, while Honda came in second with 113 defects. The study was based on responses of approximately 65,000 new car owners queried during their first 90-days of ownership.

These results do not surprise us, as we have been fortunate to make numerous sojourns to the Toyota plant in Georgetown, Kentucky, and observe the manufacturing processes. These trips were normally facilitated by a former Japanese student of ours, Minako Yanke, …

The Distribution Of Internal Interfaces In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Paul Wynblatt

Faculty Publications

This work was supported by the MRSEC program of the National Science Foundation under Award Number DMR-0079996. Recent advances both in experimental instrumentation and computing power have made it possible to interrogate the distribution of internal interfaces in polycrystals and the three dimensional structure of the grain boundary network with an unprecedented level of detail. The purpose of this paper is to review techniques that can be used to study the mesoscopic crystallographic structure of grain boundary networks and to summarize current findings. Recent studies have shown that grain surfaces within dense polycrystals favor the same low energy planes that …

Robust Pi Controller Design Satisfying Sensitivity And Uncertainty Specifications, O. Yaniv, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

This paper presents a control design method for determining proportional-integral-type controllers satisfying specifications on gain margin, phase margin, and an upper bound on the (complementary) sensitivity for a finite set of plants. The approach can be applied to plants that are stable or unstable, plants given by a model or measured data, and plants of any order, including plants with delays. The algorithm is efficient and fast, and as such can be used in near real-time to determine controller parameters (for online modification of the plant model including its uncertainty and/or the specifications). The method gives an optimal controller for …

Thermodynamic Determination Of The Cation Distribution In Nixmn1-Γ-Xfe2+Γo4 Ferrites, Qiangmin Wei, Brian W. Robertson

Department of Mechanical and Materials Engineering: Faculty Publications

The cation distribution in the spinel ferrite system NixMn1-γ-xFe2+γO4 (x = 0, 0.25, 0.5, 0.75 and γ = 0.137) has been calculated analytically in complete form as a function of thermodynamic parameters. A generalized theoretical framework based on the O’Neill–Navrotsky model and Newton methods was used to solve a multicomponent system for up to 10 cation species. The relationship between the cation distribution and composition is given. The results are shown to agree with the available experimental results.

Disasters And Energy Security Management, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

In the past, natural disasters, such as hurricanes, floods, tornados, and earthquakes, were one of our major concern. Now, terrorist events are becoming more common and more destructive. Whether, natural or man made, a disaster can happen at any time, often with little or no advance warning. A disaster can leave many people without adequate medical services, potable water, electrical service and communications for long periods of time. They can be as destructive as Hurricane Mitch leaving several hundred-thousand people homeless or as minor as an afternoon thunderstorm knocking down local power lines to your home. Not only can lives …

Screw Dislocation Interacting With Twin Interfacial Edge Cracks Between Two Bonded Dissimilar Piezoelectric Strips, Xiangfa Wu, Yuris A. Dzenis, Tian-You Fan

Department of Engineering Mechanics: Faculty Publications

This paper is concerned with the electroelastic potentials and the fracture parameters of a twin-edge-cracked piezoelectric bimaterial strip with a screw dislocation. By means of conformal mapping technique and the known dislocation solution, the antiplane displacement and inplane electric potentials are obtained in closed-form. The intensity factors and the energy release rate are extracted explicitly. In some limiting cases, the present solutions cover those in the literature.

Complying With Florida's Green Land Development Standard: Case Studies And Lessons Learned, Florida Solar Energy Center, Robin Vieira

FSEC Energy Research Center®

The Florida Green Building Coalition, Inc. (FGBC), developed a standard for green land development. It is the first voluntary, non-government standard of its kind to target an entire state. Other groups have created development standards that apply to just a local Home Building Associations (HBA) or a local jurisdiction. The U.S. Green Building Council (USGBC) is beginning a Leadership in Energy & Environmental Design (LEEDTM) for neighborhoods. To comply with Florida's standard, a developer has to earn sufficient points among six categories:

1. Protect Ecosystems and Conserve Natural Resources: for example, surveys, conservation areas, wildlife corridors, wetland preservation and management
2. Circulation: …

The Benefits Of Using Window Shades, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

Windows play an important aesthetic role in our daily lives. At the same time, windows typically add significantly to the cost of heating and cooling buildings. After reviewing the physical principles by which windows add heat to buildings and the standard techniques employed to reduce unwanted heating, this paper focuses on one type of device which is readily available, inexpensive to purchase and operate, and capable of being adjusted to changing conditions on even an hourly basis. The device is the common window shade. This paper develops a simple, but realistic, model for computing the advantage of using reflective interior …

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic: Quarterly Progress Report (Aug. 01 – Oct. 31, 2003), Yingtao Jiang, Bingmei Fu

Transmutation Sciences Materials (TRP)

The experimental setup designed and manufactured in UNLV was shipped to LANL in early Aug. One student has been working in LANL to conduct the experiment since then. In the meantime, one new Ph. D. student has started to run the simulation for transport in oxygen mixing. In Oct., a professional has been hired to work in both experimental and the theoretical studies pertaining to the proposed work.

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements: Quarterly Progress Report (June 01 – August 31, 2003), Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV), the Idaho State University (ISU), and the Los Alamos National Laboratory (LANL) is to evaluate the feasibility of determining residual stresses in cold-worked, plastically-deformed (bent), and welded materials using a nondestructive method based on positron annihilation spectroscopy (PAS). This technique uses γ-rays from a small MeV electron Linac to generate positrons inside the sample via pair production. This method is known to have capabilities of characterizing defects in thick specimens that could not be accomplished by conventional positron technique or other nondestructive methods. The generated …

External And Intrinsic Anchoring In Nematic Liquid Crystals: A Monte Carlo Study, Nikolai V. Priezjev, G. Skacej, R. A. Pelcovits, S. Zumer

Mechanical and Materials Engineering Faculty Publications

We present a Monte Carlo study of external surface anchoring in nematic cells with partially disordered solid substrates, as well as of intrinsic anchoring at free nematic interfaces. The simulations are based on the simple hexagonal lattice model with a spatially anisotropic intermolecular potential. We estimate the corresponding extrapolation length b by imposing an elastic deformation in a hybrid cell-like nematic sample. Our estimates for b increase with increasing surface disorder and are essentially temperature independent. Experimental values of b are approached only when both the coupling of nematic molecules with the substrate and the anisotropy of nematic-nematic interactions are …

Oct 2003, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Farmall Donation Storage Space Funding Opportunities

Exotendons For Assistance Of Human Locomotion, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Background: Powered robotic exoskeletons for assistance of human locomotion are currently
under development for military and medical applications. The energy requirements for such devices are excessive, and this has become a major obstacle for practical applications. Legged locomotion in many animals, however, is very energy efficient. We propose that poly-articular elastic mechanisms are a major contributor to the economy of locomotion in such specialized animals. Consequently, it should be possible to design unpowered assistive devices that make effective use of similar mechanisms.

Methods: A passive assistive technology is presented, based on long elastic cords attached to an
exoskeleton and guided …

Predictive Joint Motion Limiting In Robotic Applications, Edward Red, Brian Fielding

Faculty Publications

Three joint space algorithms slow the Cartesian path motion when it appears that joint motion is approaching a joint, speed, or acceleration limit. All three algorithms use quadratic curve fitting to predict where the joint motion is heading, followed by a prediction as to how much time would elapse until a limit is reached.

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Iii Quarterly Report, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. The third phase concludes the experimental a fluid flow study and optimization study. The first quarter and second quarter of phase three also begins the experimental set-up of secondary emission studies from niobium in superconducting mode. This …

Method For Performing Accelerated Characterization Of Viscoelastic Constitutive Behavior Of Asphaltic Concrete, Curtis Berthelot, D. H. Allen, Chad Searcy

Department of Engineering Mechanics: Faculty Publications

Constitutive models based in continuum mechanics are formulated for modeling the time dependent mechanical re¬sponse of asphaltic concrete. The model chosen for the initial phase of study is linear viscoelastic, resulting in stress-strain re¬lations that are of the single integral Boltzmann type in time. Experimental equipment and testing protocols are described for obtaining material properties within the viscoelastic framework selected for characterization. A frequency sweep experimental technique is described for obtaining composite properties from short-term tests that can be used to predict long-term, time-depen¬dent material behavior. Mathematical techniques are described for converting experimentally obtained complex compliances to creep compliances and …

2003 (Fall) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the fall of 2003.

On The Mechanical Response In A Thermal Barrier System Due To Martensitic Phase Transformation In The Bond Coat, Anette M. Karlsson

Mechanical Engineering Faculty Publications

Recentstudies have shown that Pt-aluminide—a common bond coat material inthermal barrier coatings—undergoes martensitic transformations during thermal cycling. The transformationsare associated with both large transformation strain and a strainhysteresis, leading to accumulation of a mismatch strain. Thermal barriersystems based on Pt-aluminide bond coats are susceptible to interfacialmorphological instabilities. In this study, we investigate how the cyclicmartensitic transformation influences the morphology. Two key results are: (i)the morphological instabilities are highly sensitive to the thermo-mechanical propertiesof the substrate due to the martensitic transformation; (ii) thehysteresis associated with cyclic martensitic transformation cannot drive the morphologicalinstabilities; the strains associated with the formation of the thermallygrown …

A Texture Evolution Model In Cubic-Orthotropic Polycrystalline System, Brent L. Adams, H. Garmestani, D. S. Li

Faculty Publications

This work has been funded under the AFOSR Grant # F49620-03-1-0011 and Army Research Lab Contract # DAAD17-02-P-0398 and DAAD 19-01-1-0742. B.L. Adams acknowledges support of Army Research Office, Proposal No. 42566-MS. The authors express their sincere gratitude to Professor Surya Kalidindi, for helpful suggestions and correspondence for the derivation of the processing path functions. A new methodology based on a conservation principle in the orientation space is developed to simulate the texture evolution in a cubic-orthotropic polycrystalline system. A least squares error method was used to improve the accuracy of the simulation results obtained from the texture evolution function. …

Thermal Transport Eveluations Related To Waste Package Design -- Model Evaluations -- Task 19, Roald Akberov

Publications (YM)

The purpose of the “Thermal Transport Evaluations Related to Waste Package Design” Task # 19 of Cooperative Agreement Number DE-FC28-98NV12081 was to develop a new CFDHT model for heat transfer and fluid flow in the potential rsepository at the Yucca Mountain, Nevada and to study the effects of forced convection during the pre-closure period and natural convection during the postclosure period. The analysis was performed for the drift dimensions shown in Figure 4-1 below. The intended use of the model is to estimate the velocity and temperature distribution as well as the highest temperature in the drift during the pre-closure …

Sufficient Conditions For Admittance To Ensure Planar Force-Assembly In Multi-Point Frictionless Contact, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

An important issue in the development of force guidance assembly strategies is the specification of an appropriate admittance control law. This paper identifies procedures for selecting the appropriate admittance to achieve reliable planar force-guided assembly for multi-point contact cases. Conditions that restrict the admittance behavior for each of the various types of two-point contact are presented. These conditions ensure that the motion that results from contact reduces part misalignment for each case. We show that, for bounded misalignments, if the conditions are satisfied for a finite number of contact configurations, the conditions ensure that force guidance is achieved for all …

Efficient Contact State Graph Generation For Assembly Applications, Feng Pan, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

An important aspect in the design of many automated assembly strategies is the ability to automatically generate the set of contact states that may occur during an assembly task. In this paper, we present an efficient means of constructing the set of all geometrically feasible contact states that may occur within a bounded set of misalignments (bounds determined by robot inaccuracy). This set is stored as a graph, referred to as an Assembly Contact State Graph (ACSG), which indicates neighbor relationships between feasible states. An ACSG is constructed without user intervention in two stages. In the first stage, all hypothetical …