Mechanical Engineering Commons^™

Piezoelectromagnetic Waves In A Ceramic Plate Between Two Ceramic Half-Spaces, S. N. Jiang, Q. Jiang, X. F. Li, S. H. Guo, H. G. Zhou, J. S. Chang

Department of Mechanical and Materials Engineering: Faculty Publications

We analyze the propagation of piezoelectromagnetic waves guided by a plate of polarized ceramics between two ceramic half-spaces. An exact dispersion relation is obtained, which reduces to a few known elastic, electromagnetic, and quasistatic piezoelectric wave solutions in the literature as special cases. Numerical solutions to the equation that determines the dispersion relation show the existence of guided waves. The results are useful for acoustic wave and microwave devices.

Modeling, Analysis, And Experimental Study Of In Vivo Wheeled Robotic Mobility, Mark E. Rentschler, Jason Dumpert, Stephen R. Platt, Karl Iagnemma, Dmitry Oleynikov, Shane M. Farritor

Department of Mechanical and Materials Engineering: Faculty Publications

Laparoscopy is abdominal surgery performed with long tools inserted through small incisions. The use of small incisions reduces patient trauma, but also eliminates the surgeon’s ability to view and touch the surgical environment directly. These limitations generally restrict the application of laparoscopy to procedures less complex than those performed during open surgery. This paper presents a theoretical and experimental analysis of miniature, wheeled, in vivo robots to support laparoscopy. The objective is to develop a wireless mobile imaging robot that can be placed inside the abdominal cavity during surgery. Such robots will allow the surgeon to view the surgical environment …

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) …

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 …

Antiplane Surface Acoustic Waves Propagating In Elastic Half-Space Coated With An Anisotropic Laminate, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Dispersion relation of antiplane surface acoustic waves (SAWs) propagating in elastic half-space coated with an anisotropic laminate was determined explicitly by means of Stroh's formalism within the subsonic range, where is no energy leakage into the substrate. During the procedure, the governing dynamic equation in each anisotropic layer and the displacement–traction continuity at interfaces were exactly satisfied by Stroh's functions. Explicit algebraic equation was derived for determining the dispersion relation. As an example, the wave number vs. phase velocity diagram for steel half-space coated with a graphite-fiber/epoxy laminate with a [± 45°/0°₂] lay-up was demonstrated. The given method …

Electrohydrodynamic Instability Of Thin Conductive Liquid Films, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

This paper considers the effect of surface charges on the surface instability of thin conductive liquid films. A characteristic relation is obtained for determining the wave number of the fastest growing mode as a function of surface tension, dispersive van der Waals force, and electrostatic tractions exerted by the film surface charges. Two natural length scales of the microsystem are further introduced to account for the coupling effects on the dewetting pattern development. The present results can be used for controlled surface pattern modulation in a spinodal-dewetting scenario via amplification of surface waves of selected modes.

Evolutionary Algorithm For The Placement Of Fluid Power Valves On A Valve Stand, Trichy M. Kethara Pasupathy, Ravi Teja Seethamraju, Robert G. Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

The choice of placement of fluid power valves on a valve stand and routing by pipes has an impact on operational costs. Choosing the right placement that provides optimum routing configuration or determining the optimum routing for a chosen placement are both computationally hard problems. An evolutionary algorithm (EA), to minimize operational costs while optimizing placement and routing of valves, is developed here. The best practices in the industry are abstracted and implemented in the EA. In this paper, the algorithm and its performance for examples with varying complexities are presented. Our results meet or exceed experienced designers’ solutions.

Experimental Determination Of Probabilistic Edge-Delamination Strength Of A Graphite–Fiber/Epoxy Composite, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Probabilistic edge-delamination strength of a thermosetting polymer composite was studied experimentally in this work. During the procedure, by means of edge-delamination tensile test, the graphite–fiber/epoxy laminate made of unidirectional Toray P7051S- 20Q-1000 prepregs with an optimized lay-up of [12₂/–12₂/0₂]_S was used for examining its probabilistic distributions of the edgedelamination onset stress and the ultimate tensile strength. Acoustic emission (AE) equipment and optical microscope were utilized to capture the edge-delamination initiation and characterize the failure modes during delaminating. Fractographical analysis based on scanning electron microscope (SEM) was conducted for the characterization of the microscopic …

Stability Of Transport And Rate Processes [Review], Yaşar Demirel

Papers in Thermal Mechanics

About fifty years ago, the Turing instability demonstrated that even simple reaction-diffusion systems might lead to spatial order and differentiation, while the Rayleigh-Bénard instability showed that the maintenance of nonequilibrium might be the source of order in fluids subjected to a thermodynamic force above a critical value. Therefore, distance from global equilibrium in the form of magnitude of a thermodynamic force emerges as another constraint of stability; some systems may enhance perturbations, and evolve to highly organized states called the dissipative structures after a critical distance on the thermodynamic branch. Although the kinetics and transport coefficients represent short-range interactions, chemical …

Finite Element Analysis Of Covered Microstents, Linxia Gu, Swadeshmukul Santra, Robert A. Mericle, Ashok V. Kumar

Department of Mechanical and Materials Engineering: Faculty Publications

Currently available neuroendovascular devices are inadequate for effective treatment of many wide-necked or fusiform intracranial aneurysms and intracranial carotid-cavernous fistulae (CCF). Placing a covered microstent across the intracranial aneurysm neck and CCF rent could restore normal vessel morphology by preventing blood flow into the aneurysm lumen or CCF rent. To fabricate covered microstents, our research group has developed highly flexible ultra thin (~150 μm) silicone coverings and elastomerically captured them onto commercially available metal stents without stitching. Preliminary in vivo studies were conducted by placing these covered microstents in the common carotid artery of rabbits. The feasibility of using covered …

Determination Of Dynamic Delamination Toughness Of A Graphite-Fiber/Epoxy Composite Using Hopkinson Pressure Bar, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Modified dynamic three-point-bending and compact shearing test configurations based on Hopkinson pressure bar (HPB) and crack detection gage (CDG) (Vishay Intertechnology, Inc) were used for the determination of the dynamic mode I and mode II delamination-initiation toughness of a unidirectional graphite-fiber/epoxy composite made of P7051S-20Q-1000 prepregs (Toray Composites America). The transient loading history was recorded precisely by the HPB installed with a highresolution digital oscilloscope, and the crack initiation and delay time were captured using the CDG. By means of dynamic finite-element analysis (FEA) of the impact processes with the loading history and crack initiation time as input, the critical …

Test 1852: Massey Ferguson 596 And 492 Diesel 12-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1855: John Deere 4720 Ehydro Diesel Hydrostatic, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1854: John Deere 4520 Ehydro Diesel Hydrostatic, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Nebraska Summary 571: Case-Ih Jx1085c Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1856: Mccormick Mtx 120 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1869: John Deere 5525 Diesel 12-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1866: John Deere 5225 Diesel 9-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Nebraska Summary 572: Case-Ih Jx1095c Diesel 12-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1860: Challenger Mt835b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Electronic Commerce Negotiation In A Supply Chain Via Constraint Evaluation, R. Wilhelm, B. Chu, R. Sun

Department of Mechanical and Materials Engineering: Faculty Publications

Negotiation is of critical importance in e-commerce applications where the supply chain is dynamic and reconfiguring. In this research supply chain negotiation problems are addressed as constraint-satisfaction problems. In general each negotiation is handled in the largest scope possible to avoid the suboptimality that can result from many local solutions. This global approach, however, must be balanced with time constraints that apply in e-commerce supply chain execution. In this paper, we describe a new approach for e-commerce supply chain negotiation via constraint evaluation. As well, results from prototype software, distributed across the internet, are discussed. Beyond the general formulation, we …

Test 1841: Kubota M120dt Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Tractor Test 1865: Massey Ferguson 481 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 2259: Case Ih Mxu125 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1858: Mccormick Mtx 150 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 2258: New Holland Ts125a Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Tests 2274 & 2275: Challenger Mt425b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Tests 2305 & 2306: Challenger Mt555b Autopower Iv Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 2335: Challenger Mt565b Techstar Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1859: Challenger Mt755b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.