Mechanical Engineering Commons^™

Detection And Classification Of Impact-Induced Damage In Composite Plates Using Neural Networks, Rohit Dua, Steve Eugene Watkins, Donald C. Wunsch, K. Chandrashekhara, Farhad Akhavan

Electrical and Computer Engineering Faculty Research & Creative Works

Artificial neutral networks (ANN) can be used as an online health monitoring systems (involving damage assessment, fatigue monitoring and delamination detection) for composite structures owing to their inherent fast computing speeds, parallel processing and ability to learn and adapt to the experimental data. The amount of impact-induced strain on a composite structure can be found using strain sensors attached to composite structures. Prior work has shown that strain-based ANN can characterize impact energy on composite plates and that strain signatures can be associated with damage types and severity. This paper reports the extension of this approach for damage classification using …

Task Specific Uncertainty In Coordinate Measurement, R. G. Wilhelm, R. Hocken, H. Schwenke

Department of Mechanical and Materials Engineering: Faculty Publications

Task specific uncertainty is the measurement uncertainty associated with the measurement of a specific feature using a specific measurement plan. This paper surveys techniques developed to model and estimate task specific uncertainty for coordinate measuring systems, primarily coordinate measuring machines using contacting probes. Sources of uncertainty are also reviewed.

On Modular Design Of Field Robotic Systems, Shane Farritor, Steven Dubowsky

Department of Mechanical and Materials Engineering: Faculty Publications

Robots are needed to perform important field tasks such as hazardous material clean-up, nuclear site inspection, and space exploration. Unfortunately their use is not widespread due to their long development times and high costs. To make them practical, a modular design approach is proposed. Prefabricated modules are rapidly assembled to give a low-cost system for a specific task. This paper described the modular design problem for field robots and the application of a hierarchical selection process to solve this problem. Theoretical analysis and an example case study are presented. The theoretical analysis of the modular design problem revealed the large …

Bicycle Braking System, Noel Brady

Patents

A bicycle braking system for permitting controlled rotation and continuous power to the wheels of a bicycle during braking of the bicycle to enhance control of the bicycle during braking includes a cylindrical brake pad that is spring loaded within angled slots in a casing. The brake pad is positioned proximate the rim of a wheel and a cable assembly is coupled to the brake pad for urging the brake pad towards an end of the angled slots and against the rim of the wheel to slow rotation of the wheel.

Using A Rapid Prototyping Machine In The Integrated Kinematics, Dynamics, And Machine Design Lab, Wieslaw M. Szydlowski

Department of Mechanical and Materials Engineering: Faculty Publications

According to a recent trend, two different labs - the Machine Design lab, and Kinematics, and Dynamics lab are combined into one integrated lab. The time students spend on their projects is halved. To save the quality of undergraduate education, an ew methodology has to be developed. The paper explains the methodology developed by the author while teaching the integrated Kinematics, Dynamics, and Machine Design Lab (MECH 488) at the Mechanical Engineering Department of the University of Nebraska-Lincoln.

The objective of the aforementioned lab is to teach the students, who have no design experience, how to select proper tools (firom …

Optimization Of A Multi-Aixs Electro-Mechanical Scanning System., Raul Urbina

Electronic Theses and Dissertations

This thesis presents efforts to enhance the system performance of an ultrasonic scanning machine. New developments in electronics are used to enhance the system performance. This work focuses on optimizing the system repeatability with a robust triggering system for the scanner. The robust triggering system applies new advances in programmable logic devices that make the replacement of complicated digital circuits possible. Modeling of wave propagation through anisotropic media is used to increase the system dynamic range. The model-based gain control compensates for variations in thickness and materials by controlling the excitation pulse amplitude. The automatic gain is implemented using integrated …

The Flexural Response Of Bolted Composite Panels At Elevated Temperature, Christopher Gary Malm

Electronic Theses and Dissertations

Carbon fiberlcyanate ester matrix composite panels with bolted connections to aluminum endplates were tested in four point bending at room and elevated temperatures. The specimens tested were subcomponents of the NASA X-38 Crew Return Vehicle. The X-38 is the proposed escape vehicle for the International Space Station, currently being constructed in Earth orbit. During reentry into the Earth's atmosphere, the composite aeroshell of the X-38 is expected to experience elevated temperatures, which makes accurate characterization of material properties at elevated temperature imperative to a sound design. Three varieties of specimens were tested: flat composite laminates, hat-stiffened composite laminates, and sandwich …

Mathematical Modeling For Fabricating A Microstructure With A Pre-Specified Geometry Using Laser -Induced Chemical Vapor Deposition, Chaoyang Zhang

Doctoral Dissertations

Laser-induced chemical vapor deposition (LCVD) is an emerging new technique with many practical applications. To optimize the system for fabricating a microstructure with a pre-specified geometry in pyrolytic LCVD, a three-dimensional mathematical model is developed for predicting temperature distributions and laser dwell times across the substrate scanned by the laser beam. A microstructure is fabricated layer by layer, and for each layer the laser beam moves from one pixel to the next. The complicated correlations among temperature distribution, deposit growth rate, and laser dwell time are investigated. A purely heterogeneous reaction is assumed and any gas-phase transport is ignored.

A …

Nebraska Summary 388: Fendt 918 Vario 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 …

Nebraska Summary 391: Fendt 926 Vario 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 1790: 9300 T 24 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1796: Case Ih Stx 275/New Holland Tj 275 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1797: Case Ih Stx 325/New Holland Tj 325 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Preparation Of Ordered Macroporous Sr0.5sm0.5coo3 As Cathode For Solid Oxide Fuel Cells, Fanglin Chen, Changrong Xia, Meilin Liu

Faculty Publications

Ordered macroporous Sr_0.5Sm_0.5CoO₃ structrures with an average pore size of 140 nm have been prepared using closepacked arrangement of monodispersed polystyrene spheres as templates. A fuel cell using ordered macroporous Sr_0.5Sm_0.5CoO₃ as the cathode, gadolinia-doped ceria (GDC) film as the electrolyte, and GDC–NiO as the anode generated maximum power densities of 150, 196 and 267 mW/cm² at 500, 550 and 600 °C, respectively.

Eddy Structures Induced Within A Wedge By A Honing Circular Arc, C. P. Hills

Articles

In this paper we outline an expeditious numerical procedure to calculate the Stokes flow in a corner due to the rotation of a scraping circular boundary. The method is also applicable to other wedge geometries. We employ a collocation technique utilising a basis of eddy (similarity) functions introduced by Moffatt (1964) that allows us to satisfy automatically the governing equations for the streamfunction and all the boundary conditions on the surface of the wedge. The circular honing problem thereby becomes one-dimensional requiring only the satisfaction of conditions on the circular boundary. The advantage of using the Moffatt eddy functions as …

Eddies Induced In Cylindrical Containers By A Rotating End Wall, Christopher Hills

Articles

The flow generated in a viscous liquid contained in a cylindrical geometry by a rotating end wall is considered. Recent numerical and experimental work has established several distinct phases of the motion when fluid inertia plays a significant role. The current paper, however, establishes the nature of the flow in the thus far neglected low Reynolds number regime. Explicitly, by employing biorthogonality relations appropriate to the current geometry, it is shown that a sequence of exponentially decaying eddies extends outward from the rotating end wall. The cellular structure is a manifestation of the dominance of complex eigensolutions to the homogeneous …

To Research, Analyse And Install An Optimised Maintenance Management System For A Medium Sized Manufacturing Company: A Textile Company Case Study, Christopher O'Donoghue

Theses

Modern manufacturing is continually striving to ensure that products are made to higher levels of quality with faster lead times and at the lowest possible costs. Manufacturing production has never been more reliant on machines and automated processes than it is today. This thesis investigates the management philosophies that are in existence, which cater specifically for maintenance and maintenance related issues. Management philosophies such as Reliability Centred Maintenance (RCM), Total Productive Maintenance (TPM), Profit Centred Maintenance (PCM), asset management (AM), Predictive Maintenance (PdM), Condition Based Maintenance (CBM) and World Class Maintenance (WCM) have increased company profits by drastically reducing maintenance …

The Role Of Mechanical Design In Mechatronics Education, John Gardner

Mechanical and Biomedical Engineering Faculty Publications and Presentations

A survey of Mechatronics course offerings around the United States shows a rich variety of approaches to this topic.[1] Indeed, it appears that a majority of Mechanical Engineering programs across the county offer some formal offering in this area and it seems clear that the vast majority of Mechatronics courses are offered through Mechanical Engineering departments. With the traditional emphasis on design skill in mechanical engineering, it would seem obvious that mechatronics courses would feature a major design component. Surprisingly, very few existing mechatronics courses (at least those reported in the literature) feature a strong emphasis on mechanical design. That …

Microstructure-Sensitive Design Of A Compliant Beam, Brent L. Adams, Alisa J. Millar Henrie, B. Henrie, M. Lyon, H. Garmestani, Surya R. Kalidindi

Faculty Publications

BA acknowledges financial support provided by the MRSEC Program of the National Science Foundation under Award Number DMR-9632556. SK acknowledges financial support from National Science Foundation under Award Number CMS-9732699. BA, SK and HG also acknowledge support from the NSF-CIRE program centered at Florida A&M University, facilitating collaborations. Support was also provided by the College of Engineering and Technology at BYU (AH, BH and ML). Computations were performed on the new SGI Origin 2000 supercomputer at Brigham Young University, donated by Ira Fulton. We show that mechanical design can be conducted where consideration of polycrystalline microstructure as a continuous design …

Finite Element Analysis And Active Control For Nonlinear Flutter Of Composite Panels Under Yawed Supersonic Flow, Khaled Abdel-Motagaly

Mechanical & Aerospace Engineering Theses & Dissertations

A coupled structural-electrical modal finite element formulation for composite panels with integrated piezoelectric sensors and actuators is presented for nonlinear panel flutter suppression under yawed supersonic flow. The first-order shear deformation theory for laminated composite plates, the von Karman nonlinear strain-displacement relations for large deflection response, the linear piezoelectricity constitutive relations, and the first-order piston theory of aerodynamics are employed. Nonlinear equations of motion are derived using the three-node triangular MIN3 plate element. Additional electrical degrees of freedom are introduced to model piezoelectric sensors and actuators. The system equations of motion are transformed and reduced to a set of nonlinear …

Radiative Interactions In Thermochemical Nonequilibrium Expanding Flows, Srikanth B. Pidugu

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical study is conducted to investigate radiative interactions in flows with thermal and chemical nonequilibrium. The two dimensional spatially elliptic Navier-Stokes equations have been used to numerically investigate different physical processes in the nozzle flow problem. The system of governing equations are solved using explicit, unsplit MacCormack predictor-corrector scheme. The chemistry source term is treated implicitly to alleviate stiffness associated with fast chemical reactions.

Different physical processes considered in this study are investigated in a systematic manner. Finite chemical processes in chemically reacting supersonic nozzle flows are studied. Five hydrogen-air combustion models have been employed to study the influence …