Engineering Commons^™

Investigating The Relationship Between Material Property Axes And Strain Orientations In Cebus Apella Crania, Christine M. Dzialo

Masters Theses 1911 - February 2014

Probabilistic finite element analysis was used to determine whether there is a statistically significant relationship between maximum principal strain orientations and orthotropic material stiffness orientations in a primate cranium during mastication. We first sought to validate our cranium finite element model by sampling in-vivo strain and in-vivo muscle activation data during specimen mastication. A comparison of in vivo and finite element predicted (i.e. in silico) strains was performed to establish the realism of the FEM model. To the best of our knowledge, this thesis presents the world’s only complete in-vivo coupled with in-vitro validation data set of a primate cranium …

A Nonlinear Model For Wind-Induced Oscillations Of Trees, Lakshmi Narayanan Ramanujam

Masters Theses 1911 - February 2014

Ambient wind causes trees to oscillate. Wind-induced oscillations of trees constitute a fluid-structure interaction problem, which has been studied by many researchers from various points of view. However, there is yet a lot to be done. From an engineering point of view, the complex structure of trees, which are very different from man-made structures, as well as the highly nonlinear interaction between wind and tree, makes it a challenging task to predict the amplitude and frequency of the resulting oscillations. From a biological point of view, the influence of wind on photosynthesis as well as the growth and death of …

Physical Model Of The Feeding Strike Of The Mantis Shrimp, Suzanne M. Cox

Masters Theses 1911 - February 2014

A physical model was built to study the properties of the feeding strike of the mantis shrimp that are responsible for drag reduction and cavitation control. The model had three goals: 1) The model was to be outfitted with a method to collect kinematic, force and cavitation data. 2) The velocity and acceleration profile of the model were to be predicted with a mathematical model of the mechanism. 3) The model was to match as many drag and cavitation sensitive properties of the mantis shrimp strike as feasible and have a means to control the rest. The first iteration of …

High Speed Flow Simulation In Fuel Injector Nozzles, Sukanta Rakshit

Masters Theses 1911 - February 2014

Atomization of fuel is essential in controlling combustion inside a direct injection engine. Controlling combustion helps in reducing emissions and boosting efficiency. Cavitation is one of the factors that significantly affect the nature of spray in a combustion chamber. Typical fuel injector nozzles are small and operate at a very high pressure, which limit the study of internal nozzle behavior. The time and length scales further limit the experimental study of a fuel injector nozzle. Simulating cavitation in a fuel injector will help in understanding the phenomenon and will assist in further development.

The construction of any simulation of cavitating …

A Computational Simulation Of Supercritical Carbon Dioxide And Ethanol Capillary Flow, Thomas W. Furlong

Masters Theses 1911 - February 2014

Homogenous and separated flow methods have been presented for use in the capillary tube section of the Plasma Rapid Expansion of Supercritical Solutions (PRESS) process using a carbon dioxide and ethanol mixture as the working fluid. Each method was validated against experimental expansion processes using pure carbon dioxide, isobutane, and R-134a. The results have indicated that both the homogenous flow method and the separated flow method produce results within an acceptable margin of error. By accounting for the phase interactions the separated flow method produces more accurate results with mean errors of 8.03%, 4.57%, and 5.77% for carbon dioxide, isobutane, …

Extensional-Flow-Induced Crystallization Of Polypropylene, Erica E. Bischoff White

Masters Theses 1911 - February 2014

A filament stretching extensional rheometer was used to investigate the effect of uniaxial flow on the crystallization of polypropylene. Samples were heated to a temperature above the melt temperature to erase their thermal and mechanical histories. The Janeschitz-Kriegl protocol was applied and samples were stretched at various extension rates to a final strain of e = 3.0. Differential scanning calorimetry was applied to crystallized samples to measure the degree of crystallinity. The results showed that a minimum extension rate, corresponding to a Weissenberg number of approximately Wi = 1, is required for an increase in percent crystallization to occur. Below …

Multidimensional Modeling Of Condensing Two-Phase Ejector Flow, Michael F. Colarossi

Masters Theses 1911 - February 2014

Condensing ejectors utilize the beneficial thermodynamics of condensation to produce an exiting static pressure that can be in excess of either entering static pressure. The phase change process is driven by both turbulent mixing and interphase heat transfer. Semi-empirical models can be used in conjunction with computational fluid dynamics (CFD) to gain some understanding of how condensing ejectors should be designed and operated.

The current work describes the construction of a multidimensional simulation capability built around an Eulerian pseudo-fluid approach. The transport equations for mass and momentum treat the two phases as a continuous mixture. The fluid is treated as …

Numerical Investigation Of Gas-Particle Supersonic Flow, Mihir A. Samel

Masters Theses 1911 - February 2014

No abstract provided.

Load Hindcasting: A Retrospective Regional Load Prediction Method Using Reanalysis Weather Data, Jonathan D. Black

Masters Theses 1911 - February 2014

The capacity value (CV) of a power generation unit indicates the extent to which it contributes to the generation system adequacy of a region’s bulk power system. Given the capricious nature of the wind resource, determining wind generation’s CV is nontrivial, but can be understood simply as how well its power output temporally correlates with a region’s electricity load during times of system need. Both wind generation and load are governed by weather phenomena that exhibit variability across all timescales, including low frequency weather cycles that span decades. Thus, a data-driven determination of wind’s CV should involve the use of …

Parallel Mesh Adaptation And Graph Analysis Using Graphics Processing Units, Timothy P. Mcguiness

Masters Theses 1911 - February 2014

In the field of Computational Fluid Dynamics, several types of mesh adaptation strategies are used to enhance a mesh’s quality, thereby improving simulation speed and accuracy. Mesh smoothing (r-refinement) is a simple and effective technique, where nodes are repositioned to increase or decrease local mesh resolution. Mesh partitioning divides a mesh into sections, for use on distributed-memory parallel machines. As a more abstract form of modeling, graph theory can be used to simulate many real-world problems, and has applications in the fields of computer science, sociology, engineering and transportation, to name a few. One of the more important graph analysis …

Numerical Forcing Of Horizontally-Homogeneous Stratified Turbulence, Kaustubh J. Rao

Masters Theses 1911 - February 2014

It is often desirable to study simulated turbulent flows at steady state even if the flow has no inherent source of turbulence kinetic energy. Doing so requires a numerical forcing scheme and various methods have been studied extensively for turbulence that is isotropic and homogeneous in three dimensions. A review of these existing schemes is used to form a framework for more general forcing methods. In this framework, the problem of developing a forcing scheme in Fourier space is abstracted into the two problems of (1) prescribing the spectrum of the input power and (2) specifying a force that has …

Tunable Band Gaps In Bilayer Graphene-Bn Heterostructures, Ashwin Ramasubramaniam, Doron Naveh, Elias Towe

Mechanical and Industrial Engineering Faculty Publication Series

We investigate band-gap tuning of bilayer graphene between hexagonal boron nitride sheets, by external electric fields. Using density functional theory, we show that the gap is continuously tunable from 0 to 0.2 eV, and is robust to stacking disorder. Moreover, boron nitride sheets do not alter the fundamental response from that of free-standing bilayer graphene, apart from additional screening. The calculations suggest that the graphene-boron nitride heterostructures could provide a viable route to graphene-based electronic devices.

Simulations Of Flow Over Wind Turbines, Dnyanesh A. Digraskar

Masters Theses 1911 - February 2014

One of the most abundant sources of renewable energy is wind. Today, a considerable amount of resources are being utilized for research on harnessing the wind energy efficiently. Out of all the factors responsible for efficient energy production, the aerodynamics of flow around the wind turbine blades play an important role. This work aims to undertake aerodynamic analysis of a Horizontal Axis Wind Turbine. A steady state, incompressible flow solver for multiple reference frames, MRFSimple- Foam is modified and used for performing simulations of flow over National Renewable Energy Laboratory Phase VI wind turbine rotor. The code is first tested …

Investigation Of 3-D Heat Transfer Effects In Fenestration Products, Sneh Kumar

Masters Theses 1911 - February 2014

Buildings in USA consume close to 40% of overall energy used and fenestration products (e.g. windows, doors, glazed-wall etc.) are the largest components of energy loss from buildings. Accurate evaluation of thermal performances of fenestration systems is critical in predicting the overall building energy use, and improving the product performance. Typically, two-dimensional (2-D) heat transfer analysis is used to evaluate their thermal performance as the 3-D analysis is highly complex process requiring significantly more time, effort, and cost compared to 2-D analysis. Another method of evaluation e.g. physical test in a hotbox is not possible for each product as they …

Advanced Blade Testing Methods For Wind Turbines, Puneet Malhotra

Masters Theses 1911 - February 2014

This thesis consists of a detailed analysis of different blade testing methods and improvements to a novel concept for tri-axial testing of large wind turbine blades. As the blades are one of the most critical components of the wind turbine, they have to be tested in order to ensure that their specifications are consistent with the actual performance of the blade. It must be demonstrated that the blade can withstand both the ultimate loads and the fatigue loads to which the blade is expected to be subjected during its design service life. There are basically two types of blade testing: …

Interatomic Potentials For Hydrogen In A-Iron Based On Density Functional Theory, Ashwin Ramasubramaniam, Emily Carter, Mitsuhiro Itakura

Mechanical and Industrial Engineering Faculty Publication Series

We present two interatomic potentials for hydrogen in α–iron based on the embedded atom method potentials for iron developed by Mendelev et al. Philos. Mag. 83 3977 (2003) and Ackland et al. J. Phys.: Condens. Matter 16 S2629 (2004). Since these latter potentials are unique among existing iron potentials in their ability to produce the same core structure for screw dislocations as density functional theory (DFT) calculations, our interatomic potentials for hydrogen in iron also inherit this important feature. We use an extensive database of energies and atomic configurations from DFT calculations to fit the cross interaction of hydrogen with …

Drag Reduction In Turbulent Flows Over Micropatterned Superhydrophobic Surfaces, Robert J. Daniello

Masters Theses 1911 - February 2014

Periodic, micropatterned superhydrophobic surfaces, previously noted for their ability to provide drag reduction in the laminar flow regime, have been demonstrated capable of reducing drag in the turbulent flow regime as well. Superhydrophobic surfaces contain micro or nanoscale hydrophobic features which can support a shear-free air-water interface between peaks in the surface topology. Particle image velocimetry and pressure drop measurements were used to observe significant slip velocities, shear stress, and pressure drop reductions corresponding to skin friction drag reductions approaching 50%. At a given Reynolds number, drag reduction was found to increase with increasing feature size and spacing, as in …

Analytical Modeling Of Tree Vibration Generated During Cutting Process, Payman Karvanirabori

Masters Theses 1911 - February 2014

There are several ways to cut down a tree. The piece by piece cutting method is studied in this research. By modeling the cutting process into simple dynamic models and obtaining governing equations of motion of tree and cut piece in each model, the forces during cutting process were calculated. The method was then applied to a set of real data and tree vibrations were compared with field measurements. The study is very rare in the case of the variety of the topics it covers from dynamics and mechanics to finite element modeling of a biological system.

Edge-Stress Induced Warping Of Graphene Sheets And Nanoribbons, Ashwin Ramasubramaniam, Y. Zhang, C. Reddy, V. Shenoy

Mechanical and Industrial Engineering Faculty Publication Series

We show that edge stresses introduce intrinsic ripples in freestanding graphene sheets even in the absence of any thermal effects. Compressive edge stresses along zigzag and armchair edges of the sheet cause out-of-plane warping to attain several degenerate mode shapes. Based on elastic plate theory, we identify scaling laws for the amplitude and penetration depth of edge ripples as a function of wavelength. We also demonstrate that edge stresses can lead to twisting and scrolling of nanoribbons as seen in experiments. Our results underscore the importance of accounting for edge stresses in thermal theories and electronic structure calculations for freestanding …

Investigation Of Contact Pressure Distribution On Sheet Metal Stamping Tooling Interfaces: Surface Modeling, Simulations, And Experriments, Sripati Sah

Masters Theses 1911 - February 2014

In stamping operations, sheet metal is formed into a desired shape by pressing it in a hydraulic or mechanical press between suitably shaped dies. As a predominant manufacturing process, sheet metal forming has been widely used for the production of automobiles, aircraft, home appliances, beverage cans and many other industrial and commercial products. A major effort till date on stamping processes monitoring has been focused on investigating variations in the press force. Given that the press force itself is an integral of the contact pressure distribution over the die and binder contact interfaces, it is conceivable that defects may be …

Three-Dimensional Simulations Of Self-Assembly Of Hut Shaped Si-Ge Quantum Dots, Ashwin Ramasubramaniam, V. Shenoy

Mechanical and Industrial Engineering Faculty Publication Series

This article presents the results of three-dimensional modeling of heteroepitaxial thin film growth with the objective of understanding recent experiments on the early stages of quantum dot formation in SiGe/Si systems. We use a continuum model, based on the underlying physics of crystallographic surface steps, to study the growth of quantum dots, their spatial ordering and coarsening behavior. Using appropriate parameters, obtained from atomistic calculations, the (100) orientation is found to be unstable under compressive strains. The surface energy now develops a minimum at an orientation that may be interpreted as the (105) facet observed in SiGe/Si systems. This form …

Mechanical Behavior Of A Continuous Fiber Reinforced Sic/Rbsn Ceramic Composite, Nancy M. Narbut

Masters Theses 1911 - February 2014

The purpose of the following research was to obtain an understanding of both ambient and elevated temperature mechanical behavior of a SiC fiber reinforced RBSN composite. At ambient temperature, applicability of available mechanics models to describe the stress-strain curve were examined. Emphasis was also placed on fracture toughness, R-curve behavior, and toughening mechanisms as well as the applicability of available fracture mechanics models to describe toughening behavior. At elevated temperature, an attempt was made to characterize the short term and long term effects on the composite. The material used was a RBSN reinforced with large diameter continuous SiC fibers. A …

Utilization And Examination Of A Mass Consistent Wind Flow Model, Joanne M. Carrol

Wind Energy Center Masters Theses Collection

MATHEW, a mass consistent wind flow model is applied to given areas in Princeton and Windsor, Massachusetts for the purpose of determining wind flow fields in those areas and examining the HATIIEW program itself. The MATHEW model which was originated by Sherman at Lawrence Livermore Laboratories to give a three-component time-independent nondivergent wind velocity field. The model has been verified by its creators and is accepted as a valid method for calculating wind fields. A description of the model is given. The analytic foundation of the model is elucidated, the numerical technique is described and the architecture of the MATHEW …

Design And Evaluation Of The Umass Wf-1 Kilowatt Hour Meter, Michael George Edds, Duane Cromack

Wind Energy Center Reports

A kilowatt-hour meter was designed, built and evaluated for use with the UMass Wind Furnace. A meter, capable of measuring the variable frequency variable voltage output of the wind turbine, was needed. This report describes this somewhat unique instrument, including its design and calibration.

The Flow Field Upstream Of A Horizontal Axis Wind Turbine, K. Modarresi, R. H. Kirchhoff

Wind Energy Center Reports

A mathematical model is developed for a steady-state axi-symmetric upstream flow of a porous disc, in a uniform flow field . The special case of the upstream flow of a windmill, with and without a nacelle, is treated. First, the windmill is considered as a uniform distribution of sources and then as a linear distribution of sources. Solutions for the blade disc o f the wind field upstream are obtained in the form of stream1 ines and velocity vector components. Sample flow patterns upstream o f the blade disc o f the UMass 25 kW wind turbine are presented for …

Wind Field Analysis Around A Horizontal Axis Wind Turbine, B. C. Donner, R. H. Kirchhoff

Wind Energy Center Reports

The dynamic interaction between the WMass 25 kW wind turbine, WF-1, and the local, turbulent wind field is investigated. The integral length scale for wind speed gusts is found to range from 40 to 200 m. The system i s seen to behave as a low pass filter with a cutoff frequency of 0.03 Hz. Power i n the wind with gust frequencies below the cutoff frequency is available to the wind turbine. This represents approximately 70% of the total power in the turbulence, and about 5% of the total power in the wind. The power extraction is independent
of …

Performance Matching Of Hydraulic Energy Converters And Wind Turbines For Heating Purposes, M. G. Rolland Jr., Duane E. Cromack, William E. Heronemus

Wind Energy Center Reports

An investigation of a fluid brake device designed to convert wind energy to heat is reported for small to moderate size wind turbine applications. Fluid devices of three different geometries with vaned rotors were examined for power capacity and operating range. Converted size and geometry was related to rotational speed through a parametric study of the wind turbine and fluid energy converters. Wind tunnel tests, laboratory experiments, and analytic techniques lead to the development of three candidate hydraulic convertersmatching the 10m diameter Wind Furnace Model Four.

Mathematical Modeling Of The Dispersion Of Air Pollutants From Highways, Wesley P. Bauver

Wind Energy Center Masters Theses Collection

This work discusses the theory of the HIWAY and California Line Source highway air pollution dispersion models and describes the EPA emissions model which is used to provide emission factors for these models. A parametric study of the dispersion models is performed to show the effect of the various inputs to these models on predicted pollutant concentrations. These results indicate certain cases in which one model should be used instead of the other. These models are used to perform air quality, environmental impact assessments of two highway projects in Massachusetts. Mesoscale Analyses are also performed for these highways. Advances in …

A Continuation Of The Investigation Of The Feasibility Of Using Windpower For Space Heating In Colder Climates, Duane E. Cromack

Wind Energy Center Reports

No abstract provided.

Microprocessor Based Control System For The Umass Wind Furnace I, Daniel Handman, Richard Monopoli

Wind Energy Center Reports

To maximize the efficiency of the UMass Wind Furnace I, a microprocessor based control system has been designed. The system can control blade pitch angle, yaw direction, and generator field current. The control scheme for the system is determined by the microprocessor program. Therefore, this control system can also be used to simulate various types of mechanical, electro-mechanical, electronic, and hydraulic controllers by writing an appropriate control program.