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2000

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Articles 1 - 30 of 162

Full-Text Articles in Mechanical Engineering

Numerical Studies Of Newtonian And Viscoelastic Fluids, Felix J. Alcocer Dec 2000

Numerical Studies Of Newtonian And Viscoelastic Fluids, Felix J. Alcocer

Dissertations

The direct numerical simulation (DNS) approach is used to understand the flow behavior of Newtonian and viscoelastic fluids in porous materials, four-to-one contraction and the flow of a Newtonian fluid past an airfoil.

In simulations the viscoelastic fluid is modeled by the finitely extensible nonlinear elastic (FENE) dumbbell and Oldroyd-B models. The finite element method (FEM) is used to discretize the flow domain. The DNS results show that the permeability of a periodic porous medium depends on the wavelength used for arranging particles in the direction of flow. Specifically, it is shown that for a given particle size and porosity ...


Electro-Magnetic Control Of Cylinder Wake, Zhihua Chen Dec 2000

Electro-Magnetic Control Of Cylinder Wake, Zhihua Chen

Dissertations

The objective of this dissertation is to develop open and closed-loop control algorithms for manipulating wake flows past a solid cylinder in an electrically low-conducting fluid (e.g. seawater). The intent is to avoid both vortex shedding and flow separation from the body. It is desired to reduce the mean drag significantly and prevent the lift from becoming non-zero at all times. This is achieved through the introduction of a Lorentz force in the azimuthal direction generated by an array of permanent magnets and electrodes located on the solid structure. The array of actuators offers the advantage of making the ...


Kinematic Synthesis Of Adjustable Spatial Four And Five-Bar Mechanisms For Finite And Multiply Separated Positions, Kevin Russell Dec 2000

Kinematic Synthesis Of Adjustable Spatial Four And Five-Bar Mechanisms For Finite And Multiply Separated Positions, Kevin Russell

Dissertations

Although spatial mechanisms are more general in structure than planar mechanisms, their applications are few due to the limited number of practical design tools and the complexity of those available. It is in fact the task of the future to develop effective, but practical design tools for spatial mechanisms.

This research presents several new methods for synthesizing adjustable spatial mechanisms. The first method involves the kinematic synthesis of spatial mechanisms for multiphase motion generation. Using this method, spatial four and five-bar mechanisms can be synthesized to achieve different phases of prescribed rigid body positions. The theory of this approach has ...


Numerical Modeling And Optimization Of Waterjet Based Surface Decontamination, Konstantin Babets Dec 2000

Numerical Modeling And Optimization Of Waterjet Based Surface Decontamination, Konstantin Babets

Dissertations

The mission of this study is to investigate the high-pressure waterjet based surface decontamination. Our specific objective is to develop a practical procedure for selection of process conditions at given constraints and available knowledge. This investigation is expected to improve information processing in the course of material decontamination and assist in the implementation of the waterjet decontamination technology into practice. The development of a realistic procedure for processing of a chaotic and non-accurate information constitutes the main accomplishment of this study.

The research involved acquisition of representative information about removal of brittle, elastic and viscous deposits. As a result an ...


Numerical Stimulation Of Stress-Induced Crystallization Of Injection Molded Semicrystalline Thermoplastics, Jianxin Guo Dec 2000

Numerical Stimulation Of Stress-Induced Crystallization Of Injection Molded Semicrystalline Thermoplastics, Jianxin Guo

Dissertations

Injection molded semicrystalline plastic products exhibit variable morphology along their thickness directions. The processing conditions have a significant effect on the crystallinity distribution in the final parts. However, because of the lack of sound theoretical models for stress-induced crystallization kinetics in thermoplastics, simulations of the injection molding process of semicrystalline plastics with the consideration of stress-induced crystallization have been scarce.

A stress-induced crystallization model for semicrystalline plastics is proposed based on the theory that stress induced orientation of polymer chains increase the melting temperature of the plastics, and hence, the supercooling which is the driving force for crystallization. By assuming ...


An Experimental Study Of Low Speed Open Cavity Flows, Abraham J. Meganathan Dec 2000

An Experimental Study Of Low Speed Open Cavity Flows, Abraham J. Meganathan

Masters Theses

The experimental work is part of an ongoing study aimed at understanding and controlling of cavity instabilities by passive or active steady or unsteady fluid injection. An experimental setup has been designed to quantitatively visualize the flow-field inside the cavity for varying relative dimensions (L/D ratios of 2.0, 2.67, 3.5 and 4.5, W/D of 3.33) at low subsonic speeds ranging from 55 ft/sec to 214 ft/sec using Particle Image Velocimetry (PIV).

The results showed that PIV could provide instantaneous velocity and other flow field data inside and above the cavity. The ...


Multi-Diameter Vise Clamp And Collet Jaw, Lloyd D. Snell Nov 2000

Multi-Diameter Vise Clamp And Collet Jaw, Lloyd D. Snell

Lloyd D Snell

A machine vise has incorporated into it a pair of collet jaws that allows for the machining of top surfaces and ends of a held part. The collet jaws are secured to each of the clamping blocks on the machine vise. The collet jaws include at least one collet pocket shaped into the inside surface of each collet jaw. The collet pockets are designed to receive collet pads which are shaped to hold a generally cylindrical part with varying diameters. By having more than one collet pocket within each collet jaw, several different sizes of collet pads can be utilized ...


A Growth Mixture Theory For Cartilage, Stephen M. Klisch, Robert L. Sah, Anne Hoger Nov 2000

A Growth Mixture Theory For Cartilage, Stephen M. Klisch, Robert L. Sah, Anne Hoger

Mechanical Engineering

In this paper we present a model of growth for cartilaginous tissues in which there exists a saturated solid matrix composed of multiple constituents that may grow and remodel independently of each other. Klisch and Hoger recently developed a general theory of volumetric growth for a mixture of ν-1 growing elastic materials and an inviscid fluid, which included a treatment of two special types of internal constraints that are relevant to cartilage. Here, that theory is specialized to construct a cartilage growth model. This theory allows the constituents of the solid matrix to grow independently of each other, and can ...


A Comparison Of Two Actuators For A Semi-Active Helmholtz Resonator, Charles Birdsong, Clark J. Radcliffe Nov 2000

A Comparison Of Two Actuators For A Semi-Active Helmholtz Resonator, Charles Birdsong, Clark J. Radcliffe

Mechanical Engineering

Two electro-mechanical actuators are examined for a semi-active Helmholtz resonator acoustic device. The device is used to reflect narrow band noise back to the source in an acoustic duct. The controller and actuator are used to tune the system on-line allowing optimum performance over a range of operating conditions. Actuator. dynamics play an important role in the controller design and the operation of the device. Two variations of an electro-mechanical actuator are considered here. The first uses a dual voice coil speaker with local feedback compensation and the second uses the same speaker without the compensation. It is shown that ...


Tibiocalcaneal Kinematics Of Barefoot Versus Shod Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg Nov 2000

Tibiocalcaneal Kinematics Of Barefoot Versus Shod Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg

Mechanical Engineering Faculty Publications

Barefoot running kinematics has been described to vary considerably from shod running. However, previous investigations were typically based on externally mounted shoe and/or skin markers, which have been shown to overestimate skeletal movements. Thus, the purpose of this study was to compare calcaneal and tibial movements of barefoot versus shod running using skeletal markers. Intracortical bone pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The subjects ran barefoot, with a normal shoe, with three shoe soles and two orthotic modifications. The three-dimensional tibiocalcaneal rotations were determined ...


Contributions Of Proximal And Distal Moments To Axial Tibial Rotation During Walking And Running, T. L. Bellchamber, Antonie J. Van Den Bogert Nov 2000

Contributions Of Proximal And Distal Moments To Axial Tibial Rotation During Walking And Running, T. L. Bellchamber, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The purpose of this study was to determine the cause and effect relationship between tibial internal rotation and pronation of the foot during walking and heel–toe running. This would allow predictions of orthotic effectiveness in reducing knee pain related to excessive internal tibial rotation. Kinematic and force plate data were collected from twenty subjects performing ten running and ten walking trials across a force plate. Using a least-squares algorithm, attitude matrices for each segment in each frame were obtained and the angular velocity vector of the tibia was calculated. The intersegmental moment at the ankle was calculated from ground ...


Fish Cage Physical Scale Modeling, Michael J. Palczynski Oct 2000

Fish Cage Physical Scale Modeling, Michael J. Palczynski

Master's Theses and Capstones

Scale model tests were completed in the University of New Hampshire (UNH) Wave/Tow tank to determine the movements and forces on two different fish cage models. The results of the testing were used to validate a finite element analysis and also were scaled up to that of a full sized, deployed fish cage used for aquaculture purposes.

The first model was a “skeleton” cage (without nets) rectangular in shape. This model was moored submerged in front of a viewing window and subjected to various regular waves. The motions were then recorded nonintrusively by means of an optical system acting ...


Oct 2000, Tractor Museum Oct 2000

Oct 2000, Tractor Museum

Museum Planning and Development Documents

Open House Pedestrian Door Installed Collection of Hand Tools


Preparation Of Mesoporous Sno2-Sio2 Composite As Electrodes For Lithium Batteries, Fanglin Chen, Zhong Shi, Meilin Liu Oct 2000

Preparation Of Mesoporous Sno2-Sio2 Composite As Electrodes For Lithium Batteries, Fanglin Chen, Zhong Shi, Meilin Liu

Faculty Publications

Mesoporous SnO2–SiO2 composite stable up to 600 °C with a BET surface area of 350 m2 g-1 and an average pore size of 3.4 nm is successfully prepared, which exhibits promising cycling properties as anodes for lithium batteries


Preparation Of Mesoporous Yttria-Stabilized Zirconia (Ysz) And Ysz-Nio Using A Triblock Copolymer As Surfactant, Fanglin Chen, Meilin Liu Oct 2000

Preparation Of Mesoporous Yttria-Stabilized Zirconia (Ysz) And Ysz-Nio Using A Triblock Copolymer As Surfactant, Fanglin Chen, Meilin Liu

Faculty Publications

Mesoporous yttria-stabilized zirconia (YSZ) and YSZ-NiO have been prepared for the first time using Pluronic P103 as a structure-directing agent and inorganic chlorides as precursors in a nonaqueous medium. After being fired at 500°C for 2 h, mesostructured YSZ has a BET surface area of about 146 m2 g-1, with an average pore size of 3.8 nm, while mesostructured YSZ-NiO has a BET surface area of about 108 m2 g-1, with an average pore size of 4.5 nm.


Plastic Solder Paste Stencil For Surface Mount Technology, Christopher K. Wong, Daniel Waldorf Oct 2000

Plastic Solder Paste Stencil For Surface Mount Technology, Christopher K. Wong, Daniel Waldorf

Industrial and Manufacturing Engineering

Solder paste masks or stencils are an integral part of the manufacturing process for surface mount PCBs. This study examines the feasibility of a process for rapid creation of a solder paste stencil using thermoplastic material. CNC laser cutting of the stencil geometry is replacing traditional use of chemical etching on metal sheets to produce stencils. Laser cutting has been used to improve process speed, accuracy, and cost. This research attempts to continue to simplify and reduce costs in the stencil making process by proposing as the stencil material a common thermoplastic that can be cut easily and quickly using ...


Global Projects Prepare Wpi Students For The 21st Century, William W. Durgin, Donald N. Zwiep Oct 2000

Global Projects Prepare Wpi Students For The 21st Century, William W. Durgin, Donald N. Zwiep

Office of the Provost and Vice President of Academic Affairs Scholarship

The WPI project based curriculum, which emphasizes discovery based learning are an alternative to the traditional information transfer process, has proved successful in delivering global engineering education. More than 25% of the learning process of the students is integrated into two formal projects, the Major Qualifying Project (MQP) which is designed as a capstone for professional technical competence and the Interactive Qualifying Project (IQP) which relates science and technology to societal concerns and student needs. Both the MQP and IQP may be completed on- or off-campus. Currently, over 50% of the graduating class will have completed one of the projects ...


Statistical Representation Of A Spray As A Point Process, Shankar Subramaniam Oct 2000

Statistical Representation Of A Spray As A Point Process, Shankar Subramaniam

Shankar Subramaniam

The statistical representation of a spray as a finite point process is investigated. One objective is to develop a better understanding of how single-point statistical information contained in descriptions such as the droplet distribution function ~ddf!, relates to the probability density functions ~pdfs! associated with the droplets themselves. Single-point statistical information contained in the droplet distribution function ~ddf! is shown to be related to a sequence of single surrogate-droplet pdfs, which are in general different from the physical single-droplet pdfs. It is shown that the ddf contains less information than the fundamental single-point statistical representation of the spray, which is ...


The Effects Of Patch Properties On The Debonding Behavior Of Patched Beam-Plates, Anette M. Karlsson Oct 2000

The Effects Of Patch Properties On The Debonding Behavior Of Patched Beam-Plates, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The debonding characteristics of patched structures are investigated in this study by means of an analytical model. In particular, the effects the lay-up sequence and edge tapering of a carbon-reinforced epoxy patch, as well as the beveling of an aluminum patch, have on the initiation, stability, and extent of the debonding are considered. The results presented show that both the degree of edge-tapering and the patch properties must be carefully selected in order to optimize the patched structure. It is also shown that when designing a patched system, it is important to model the correct boundary and load conditions to ...


The Influence Of Orthotic Devices And Vastus Medialis Strength And Timing On Patellofemoral Loads During Running, R. R. Neptune, I. C. Wright, Antonie J. Van Den Bogert Oct 2000

The Influence Of Orthotic Devices And Vastus Medialis Strength And Timing On Patellofemoral Loads During Running, R. R. Neptune, I. C. Wright, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Objective. To use a musculoskeletal model and simulation of running to examine: (1) the influence of two commonly prescribed treatments for patellofemoral pain (vastus medialis oblique strengthening and orthoses) and (2) the functional significance of timing differences between vastus medialis oblique and vastus lateralis on lateral patellofemoral joint loads.

Design. A three-dimensional musculoskeletal model of the lower extremity was used to simulate running at 4 m/s.

Background. Repetitive and excessive joint loading is often associated with overuse injuries that require clinical treatments to reduce pain and restore function. Affecting one in four runners, patellofemoral pain is one of the ...


Damper For Brake Noise Reduction (Brake Drums), Jonathan A. Wickert, Adnan Akay Sep 2000

Damper For Brake Noise Reduction (Brake Drums), Jonathan A. Wickert, Adnan Akay

Jonathan A. Wickert

An apparatus of reducing unwanted brake noise has a ring damper affixed around a periphery of brake drum in a drum brake system in a manner that permits relative motion and slippage between the ring damper and the brake drum when the brake drum vibrates during braking. In a preferred embodiment, the ring damper is an almost circular ring that is inserted in a groove formed in the periphery of the brake drum. The ring damper is held in place by the groove itself and by the interference pre-load or pre-tension between the ring damper and the brake drum.


Tribological Behaviour Of Quenched And Tempered, And Austempered Ductile Iron At The Same Hardness Level Sep 2000

Tribological Behaviour Of Quenched And Tempered, And Austempered Ductile Iron At The Same Hardness Level

A.S. Md Abdul Haseeb

The tribological behaviour of ductile iron heat-treated by two different procedures viz. quenching and tempering, and austempering to an identical matrix hardness of 445 KHN is compared. Wear tests were carried out using a pin-on-disc type apparatus under dry sliding conditions at a linear speed of 1.18 m s -1. Applied load and sliding distance in the range of 7.5-30 N and 2x10 4-6x10 4 m, respectively, were used. It was observed that under all test conditions, austempered ductile iron exhibits a better wear resistance than quenched and tempered ductile iron, although both have an identical chemical composition ...


A Dynamic Optimal Trajectory Generator For Cartesian Path Following, Edward Red Sep 2000

A Dynamic Optimal Trajectory Generator For Cartesian Path Following, Edward Red

Faculty Publications

This paper considers a dynamic and adaptive trajectory generator for negotiating paths using S-curves. Applying constant jerk transitions between the constant acceleration and deceleration periods of the trajectory, the trajectory will optimally transition to the desired speed setting. Optimal is defined to be the minimum time to transition from the current speed to the set speed for the move segment when jerk and acceleration are limited. The S-curve equations will adapt to instantaneous changes in speed setting and path length. An integrated motion planner will determine allowable speeds and transitional profiles based on the remaining move distance.


A New Autonomous Underwater Vehicle For Imaging Research, C. Roman, O. Pizarro, R. Eustice, H. Singh Aug 2000

A New Autonomous Underwater Vehicle For Imaging Research, C. Roman, O. Pizarro, R. Eustice, H. Singh

Christopher N. Roman

Currently, unmanned underwater vehicles either tend to be cumbersome and complex to run, or operationally simple, but not quite suitable platforms for deep water imaging. This paper presents an alternative design in the form of a new low cost and easier to use autonomous underwater vehicle (AUV) for imaging research. The objective of the vehicle is to serve as a readily available and operationally simple tool that allows rapid testing of imaging algorithms in areas such as photomosaicking, 3D image reconstruction from a single camera, image based navigation, and multi-sensor fusion of bathymetry and optical data. These are all current ...


Axisymetric Vibrations Of Homogeneous And Sandwich Spherical Shells With A Hole At The Center, Wai-Kwong Wong Aug 2000

Axisymetric Vibrations Of Homogeneous And Sandwich Spherical Shells With A Hole At The Center, Wai-Kwong Wong

Dissertations

Based on Hamilton's principle and the theory of elasticity, both linear and nonlinear governing equations of motion are derived for elastic spherical shells. Most of the analysis is focused on the free axisymmetric vibrations of homogeneous and sandwich shallow spherical shells. The nonlinear behavior, which allows for small deflections, is also discussed.

The linear vibrations of homogeneous and sandwich shallow spherical shells with a hole at the center are investigated with emphasis placed on the effect of thickness-shear deformation and rotatory inertia. The effects of curvature and the size of the central hole are studied for free axisymmetric motions ...


On Thermal Buckling Of Patched Beam-Plates, Anette M. Karlsson, W. J. Bottega Aug 2000

On Thermal Buckling Of Patched Beam-Plates, Anette M. Karlsson, W. J. Bottega

Mechanical Engineering Faculty Publications

The behavior of uniformly heated plates is considered for the situation where a patch is adhered over a region of the structure. A variational formulation results in a self-consistent set of equations and conditions, which governs the response of the system. The nonlinear problems are solved analytically, yielding exact results within the context of the mathematical model employed. A stability criterion is established for the class of problems considered, based on the second variation of the potential energy of the composite structure, and issues of stability are assessed in this context. Three non-dimensional parameters that characterize the response of the ...


Stability And Heat Transfer Characteristics Of Condensate Fluid Layers In Reduced Gravity, James C. Hermanson, Andreas N. Alexandrou, William W. Durgin, Peder C. Pedersen, Jeffrey S. Allen Aug 2000

Stability And Heat Transfer Characteristics Of Condensate Fluid Layers In Reduced Gravity, James C. Hermanson, Andreas N. Alexandrou, William W. Durgin, Peder C. Pedersen, Jeffrey S. Allen

Office of the Provost and Vice President of Academic Affairs Scholarship

The focus of this ground-based program is the study of film condensation phenomena under variable, reduced-gravity conditions. Experimental tests, combined with numerical modeling, are employed to gain an improved understanding of the fundamental fluid physics responsible for condensate film growth, film instability and the resulting interfacial motion under variable gravity, and the corresponding implications for heat transfer. There has been relatively little research on the mechanisms operative at the film interface between condensed liquid and its vapor under reduced gravity conditions. Of particular interest are the stability characteristics of the condensate layer, and how they differ from those of films ...


Fuel Saving Strategies For Separated Spacecraft Interferometry, Timothy Mclain, Randal W. Beard, Christopher A. Bailey Aug 2000

Fuel Saving Strategies For Separated Spacecraft Interferometry, Timothy Mclain, Randal W. Beard, Christopher A. Bailey

Faculty Publications

Separated spacecraft interferometry missions will require spacecraft to move in a coordinated fashion to ensure minimal and balanced consumption of fuel. This paper develops strategies for determining interferometry mission plans that result in significant fuel savings over standard approaches. Simulation results demonstrate that valuable reductions in fuel consumption can be realized by combining the retargeting and imaging maneuvers required to image multiple stellar sources. Fuel-optimal imaging strategies have been developed for two-spacecraft interferometry missions similar to the proposed Space Technology 3 mission using chained local optimization methods. Based on these strategies, sampling pattern guidelines for space-borne interferometry missions have been ...


Trajectory Planning For Coordinated Rendezvous Of Unmanned Air Vehicles, Timothy W. Mclain, Randal W. Beard Aug 2000

Trajectory Planning For Coordinated Rendezvous Of Unmanned Air Vehicles, Timothy W. Mclain, Randal W. Beard

Faculty Publications

A trajectory generation strategy that facilitates the coordination of multiple unmanned air vehicles is developed. Of particular interest is the planning of threat-avoiding trajectories that result in the simultaneous arrival of multiple UAVs at their targets. In this approach, paths to the target are modeled using the physical analogy of a chain. A unique strength of the planning approach is the ability to specify or alter the path length by adding or subtracting links from the chain. Desirable paths to the target are obtained by simulating the dynamics of the chain where threats apply repulsive forces to the chain and ...


Jul 2000, Tractor Museum Jul 2000

Jul 2000, Tractor Museum

Museum Planning and Development Documents

Midwest Tool Collectors Annual Meeting Camp Creek Thresher's Event North Door Replaced