Mechanical Engineering Commons^™

On Stationary And Moving Interface Cracks With Frictionless Contact In Anisotropic Bimaterials, Xiaomin Deng

Faculty Publications

The asymptotic structure of near-tip fields around stationary and steadily growing interface cracks, with frictionless crack surface contact, and in anisotropic bimaterials, is analysed with the method of analytic continuation, and a complete representation of the asymptotic fields is obtained in terms of arbitrary entire functions. It is shown that when the symmetry, if any, and orientation of the anisotropic bimaterial is such that the in-plane and out-of-plane deformations can be separated from each other, the in-plane crack-tip fields will have a non-oscillatory, inverse-squared-root type stress singularity, with angular variations clearly resembling those for a classical mode II problem when …

Scaleable Stagnation-Flow Reactors For Uniform Materials Deposition: Application To Combustion Synthesis Of Diamond, K. F. Mccarty, E. Meeks, R. J. Kee, Andrew E. Lutz

All Faculty Articles - School of Engineering and Computer Science

We describe two inherently scaleable geometries for chemical-vapor- deposition and heat-transfer processes that are based on stagnation flows. The "coflow" and "trumpet-bell" designs result in radially uniform fluxes to surfaces and they optimize the use of reagents. Using a trumpet-bell burner, we have grown uniform films of diamond from a substrate-stabilized flat flame of C2H2/H2/O2.

Three Dimensional Stress Intensity Factor For Large Arrays Of Radial Internal Surface Cracks In A Cylindrical Pressure Vessel, Javier Pierola

FIU Electronic Theses and Dissertations

The objective of this study is to present the mode I stress intensity factor distribution (SIF) along the crack-front for a wide array of semicircular and semi-elliptical surface cracks inside of a pressurized thick-walled cylinder. A three-dimensional finite element package ANSYS is used to evaluate the SIF for multicracked cylinder with number of cracks from n=1 to 128, the ratio of crack-depth to the wall thickness a/t=0.05 to 0.6, the ellipticity of the crack (the crack-depth to the semi-crack length) a/c=0.2 to 1.5, the ratio of the outer to the inner radius r_o/ r_i=2. …

Performance Assessment Of Prosthetic Heart Valves Using Orifice Area Formulae And The Energy Index Method, Flavio Ballerini Souza Campos

FIU Electronic Theses and Dissertations

Valve function is commonly assessed by effective orifice area (EOA) estimates using equations derived from conservation of mass and energy. Errors have been found with the method due to difficulties in determining the valve’s coefficient of discharge (Cd). The Cd, a factor that corrects the EOA for losses in the valvular wake region, has been shown previously to vary with the Reynolds number and valve geometry. In this study, a Cardio-Vascular Duplicator (CVD) is used to determine the Cd for three types of mitral valves, operating in modes ranging from normal to severely stenotic. Since orifice area methods do not …

A Kinematically Intelligent Blackboard For Computer Aided Instruction, J. Keith Nisbett, D. Watkins, Clark R. Barker

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A CAI (computer-aided instruction) package is being developed to be used as a classroom tool for the instruction of undergraduate mechanical engineering students in an introductory kinematics of mechanisms course. This graphical environment allows the instructor to emulate on the projected graphics screen everything that is currently done on the blackboard for planar mechansims. Unlike the blackboard, the software will have the intelligence to interpret the drawings in a kinematic sense so that the drawing of the linkage will behave as a linkage. The software environment involves three principal components: (1) a sketching method for defining the linkage, (2) the …

Set-Up Saving Schemes For Printed Circuit Boards Assembly, Oded Z. Maimon, Ezey M. Dar-El, Tali F. Carmon

Industrial and Manufacturing Engineering

Focusing on a basic printed circuit board (PCB) assembly line configuration characterized by very long set-up times, we examine two scheduling methods that can significantly reduce the set-up. Both methods -the Grouped Set-Up (GSU) method that has been recently introduced in the literature and the Sequence Dependent Scheduling (SDS) method, which has not been studied in this context -are based on component commonality among PCB types. Using the typical traditional scheduling method as a benchmark, the GSU and the SDS methods are compared in terms of three performance measures: line throughput, average work-in-process (WIP) inventory level, and implementation complexity. Guidelines …

Minutes Of Tractor Test Museum Committee October 21, 1993, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Status of using tractor test building. Organizing Friends of the Tractor Test Museum

Notes From Museum Committee Meeting October, 1993, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

No abstract provided.

Integration Of Simulation Modeling And Computer Aided Production Management In Computer Integrated Enterprise, Emine Persentili, Sema E. Alptekin

Industrial and Manufacturing Engineering

Designing efficient and integrated manufacturing systems is the first step in attaining computer integrated enterprises (CIE). Integration of planning and implementation phases of manufacturing is essential for taking full advantage of the CIE. In order to design reliable and efficient manufacturing systems, the designers must consider the impacts of planning decisions made by computer aided production management (CAPM) modules on implementations held in manufacturing cells. This paper focuses on two issues. The first issue is importance and necessity of integrating CAPM modules with manufacturing cells. The second issue includes major features of the object-oriented approach and their relevance to our …

A Kalina Cycle Application For Power Generation, Mounir B. Ibrahim, Ronald M. Kovach

Mechanical Engineering Faculty Publications

A multi-component (NB₃/H₂O) Kalina-type cycle that utilizes the exhaust from a gas turbine is investigaed in this paper. The turbine-inlet pressure of 5.96 × 10⁶N/m² and temperature of 755.372 K were kept constant, as well as the working fluid temperature at the condenser outlet (at 290K). The HN₃ mass fraction at the turbine inlet was varied along with the seperator temperature and the effects on the cycle efficiency were studied. The relationships between turbine-inlet flow and the seperator-inlet. How are shown in addition to the upper and lower HN₃ mass-fraction bounds. …

Transient Flowmeter Calibration Facility, Paul J. Lefebvre, William W. Durgin

Office of the Provost Scholarship

An apparatus for defining the free surface of a moving column of a fluid in a vertical pipe to enhance the accuracy of measurements of transient rate of flow of the fluid using electromagnetic flowmeter is described. It provides a neutrally buoyant plug which stays in contact with the free surface of the column of the fluid at all times and thus defines the free surface of the fluid moving in the vertical pipe accurately and reduces the oscillations of the free surface of the fluid.

Advanced Aeronatics Design: Project Based Engineering Education At Wpi, D. J. Olinger, William W. Durgin, Andreas N. Alexandrou

Office of the Provost Scholarship

One element of WPI's project-based curriculum is its interdisciplinary Advanced Aeronautics Design Program. Students participating in the program are involved in the design, construction, and flight testing of non-traditional aircraft such as an ultralight solar-powered vehicle, microwave-powered long endurance aircraft, or a flying oblique wing. The WPI project philosophy and character are described and illustrated using examples from the AAD program.

Laboratory Testing Of The Reflectance Properties Of Roofing Materials, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Past simulation and test cell studies have shown potential reduction to building cooling loads from higher exterior surface solar reflectances (Givoni and Hoffman, 1968; Givoni, 1976; Chuan and Busching, 1983; Griggs and Shipp, 1988; Anderson, 1989; Akbari et al., 1990; Chandra and Moalla, 1991; Bansal et al., 1992). Furthermore, simulation analysis of macro-climatic effects have shown that light colored surfaces may reduce the magnitude of the urban heat island (Taha et al., 1988; Akbari et al, 1989; Akbari et al., 1992).

Figure 1 shows a graphic illustration of the potential influence of surface reflectance on roof solar heat gain. The …

Numerical Analysis Of The Pullout Problem Of A Fiber Embedded In A Matrix : Comparison With An Approximate Analytical Solution, Ivan Enrique Esparragoza

FIU Electronic Theses and Dissertations

The classical problem of pullout of a long elastic rectilinear round bar (fiber) embedded in an elastic half-space (matrix) is considered before and while local debonding occurs. An approximate analytical solution derived from the elasticity theory, the intuitive Saint Venant's principle, the idea of boundary layer in hydrodynamics, and invariant Γ-integrals is presented. The problem is analyzed numerically by means of the finite element method using the ANSYS program. The cases of loading before and after the initiation of the debonding are studied. Both approaches, analytical and numerical, are compared in order to establish the concidence between them. The discrepancy …

Exergetic Cost Analysis Of A Mechanical Exergy Recycle, Jim Mcgovern

Conference Papers

A mechanical plant that involves an exergy recycle is presented for analysis. It consists of gearboxes and a fluid coupling. There is one input of shaft power to the plant and there are three separate outputs of shaft power. An exergetic cost analysis approach is outlined and applied to the plant.

Variable Structure End Point Control Of A Flexible Manipulator, Shailaja Chenumalla, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

We treat the question of control and stabilization of the elastic multibody system developed in the Phillips Laboratory, Edwards Air Force Base, California. The controlled output is judiciously chosen such that the zero dynamics are stable or almost stable. A variable structure control (VSC) law is derived for the end point trajectory control. Although, the VSC law accomplishes precise end point tracking, elastic modes are excited during the maneuver of the arm. A Linear stabilizer is designed for the final capture of the terminal state.

A Vacuum Four-Ball Tribometer To Evaluate Liquid Lubricants For Space Applications, Masabumi Masuko, William R. Jones Jr, Ralph Jansen, Ben Ebihara, Stephen V. Pepper, Larry S. Helmick

Science and Mathematics Faculty Publications

The design and operation of a vacuum tribometer, based on the four-ball configuration, is described. This tribometer evaluates the tribological characteristics of liquid lubricants for space applications. Operating conditions include: room temperature, loads to approximately 1000N, speeds to approximately 500 rpm, and pressures of approximately 10(exp -6)Pa. Tests can also be run at atmospheric pressure with air or nitrogen. Some typical test results are included.

Optimization Of The Seating Position In A Human-Powered Vehicle, Y. Lei, Mohamed Trabia, D. Too

Mechanical Engineering Faculty Research

Until recently, most of the human-powered vehicles (HPV) were designed focusing solely on its aerodynamics characteristic. In many of these HPV designs, the rider seating position was arbitrarily chosen without consideration of its effect on the rider's comfort and cycling effectiveness. Also, there is no guarantee that the seating position is related to maximum power output. Too (1991) used an experimental approach to determine that the rider will produce the maximum anaerobic power when the seat tube angle of a bicycle is at 75° whereas Hull and Gonzalez (1990) used an engineering approach to optimize the cycling biomechanics. However several …

Measurement Of The Nonsteady Flow Field In The Opening Of A Resonating Cavity Excited By Grazing Flow, Hans R. Graf, William W. Durgin

Office of the Provost Scholarship

Flow past the opening of a cavity can excite acoustic resonance. The periodic velocity field in the region of the cavity opening has been measured for various flow conditions and the vorticity distribution has been computed from the measured data using numerical differentiation. The results indicate that the shear layer rolls up into discreet vortices, which travel across the cavity opening. Two resonances were found. The first is characterized by a single vortex being present and results in the greatest amplitude. The second is characterized by the presence of two vortices which excite a distinct but lesser amplitude resonance. As …

Minutes Tractor Test And Power Museum April 14th, 1993, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Use of tractor test building for museum.

Fred Chase Preliminary Outline For Tractor Test Museum, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

No abstract provided.

Formal Recognition Of Museum Committee 1993, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Recognition of Museum

Performance Analysis For The Ccn Collection Apparatus, Deborah K. Bircher

Opportunities for Undergraduate Research Experience Program (OURE)

This paper concerns the performance testing of a system to collect and chemically analyze cloud condensation nuclei (CCN). These are the atmospheric particles which nucleate cloud drops.

The air is humidified by passage through the "haze chamber", consisting of parallel vertical plates that are covered with cotton cloth and are kept wet by water supplied at the top edge. The plates are adiabatic , and should equilibrate in temperature at the wet bulb temperature of the incoming air. Measurements of the plate temperature with eighty thermocouples indicate behavior consistent with theory.

Another part of the system is called the CFD …

Motorized Throttle Plate, John D. Crawford

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of this project was to develop a throttle plate mechanism that can be used to simulate transient engine operation. This throttle plate was designed so as to regulate the quantity of air flow entering a Port Fuel Injected (PFI) spark ignition engine prior to the combustion of the fuel-air mixture. The throttle plate is linked to a data acquisition system in order to study the port fuel injection characteristics of the fuel-air mixture. This data acquisition system links the throttle plate angular position information to data obtained using a nonintrusive laser based diagnostic technique, therefore enabling the study …

Active Buckling Control Of Composite Plates, Bradley Wayne Gentelin

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of the research project is to investigate the feasibility of using the rapidly growing technology of smart materials in actively controlling the buckling of laminated composite plates. Advanced composite structures are susceptible to structural instabilities under compression loadings, and the proper control of such instabilities is essential to the effective performance of the structures. The focus of the research activity is to perform an experimental study of using embedded piezoelectric materials for enhancing the critical buckling loads of laminated composite plates. The forces induced by the piezoelectric actuators under the applied voltage fields will be used to counterbalance …

Two Methods For Attenuation Of Vibration In Structures, Kevin Mark Mcclendon

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this report is to discuss methods of suppressing vibration in space trusses. The discussion is centered on the approach, structural attributes, and effectiveness of each method. One approach uses structural active members which are actuated to produce “anti-vibration” to cancel vibrations in the truss. The other method is to implement passive and active damping devices at the base of the space truss, where it will absorb vibrations by fluctuating the stiffness of the structures foundation.

The Research, Design And Production Of Cortical Bone Pins And Screws For The Fixation Of Broken Bones In The Hand And Wrist, Ronald P. Holland

Opportunities for Undergraduate Research Experience Program (OURE)

Investigators at the University of Missouri at Rolla have entered into a joint venture with surgeons at Saint Louis University Hospital to develop a superior method of fixing broken bones of the human hand and wrist. This method involves the production of pins and screws from human cortical bone which will be used to fix broken bones for healing. The cortical bone fasteners will provide many advantages to the currently used metal fasteners. To date, prototype fasteners have been developed and are pending mechanical testing as a result of this undergraduate research project. Results of this project potentially include a …

Catalysis Of Charcoal Emissions, James M. Horak

Opportunities for Undergraduate Research Experience Program (OURE)

This paper is about the development of a system to reduce the emissions of charcoal kilns with the catalyst from automotive catalytic converters. This device, called the charcoal kiln emissions oxidizer (CKEO), was designed and fabricated to meet the goal of a cost effective means to reduce the carbon monoxide and hydrocarbon emissions from charcoal kilns. Testing of the CKEO was never carried out as a test site could not be secured by this writing. The need for the CKEO, the theory behind it, and a procedure to test it are presented.

Damage Assessment Of Composite Structures With Embedded Optical Fibers, Peter E. Hackett

Opportunities for Undergraduate Research Experience Program (OURE)

One of the important features of smart composite structures is their capability to observe their own performance for proper functioning and self-diagnostic purposes. The low velocity impact damage of composite structures (matrix cracking, fiber breakage, delamination, etc.) is often difficult to detect visually and can significantly reduce the strength of the structure. The objective of this research is to develop a technique for fabricating composite laminates that will facilitate the embedment of optical fibers. Composite test specimens will be fabricated in the composite material laboratory. The fabrication of composite laminates with a health monitoring and damage assessment system capable of …

Selecting Windows For South Florida Residences, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

To provide some guidance to the victims of hurricane Andrew in Dade County, we performed a study of various types of modern glazing systems that might be incorporated in windows for south Florida residences.

The dominant energy impact of residential windows in south Florida comes from the solar radiant heat gain entering these windows and the corresponding heat loads on cooling systems. Thus any extra dollars spent by homeowners to purchase improved replacement windows should be spent in lowering the solar gains of the windows purchased (by reducing glazing shading coefficients or by adding exterior shading devices or vegetation) rather …