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Articles 1 - 30 of 113
Full-Text Articles in Engineering Mechanics
An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent, Graham Lancaster
An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent, Graham Lancaster
All Theses
This research considers the problem of using bistable laminates as a mechanical deterrent to the impending impact of a particle. The structure will be controlled through an algorithm that will utilize piezoelectric devices to activate them in unison with the bistable laminate to successfully deter. A novel experimental setup will be constructed to ensure that the bistable laminate stays fixed when acting as a mechanical deterrent. Piezoelectricity is the main driving force of the bistable laminate to morph and this study will use a Macro Fiber Composite (MFC) actuator that contains piezoelectric ceramic rods in a patch to transfer electrical …
Design Decisions Under Risk And Uncertainty, Sravya Thoomu
Design Decisions Under Risk And Uncertainty, Sravya Thoomu
All Theses
In the contemporary world of engineering, engineers strive towards designing reliable and robust artifacts while considering and attempting to control manufacturing costs. In due course they have to deal with some sort of uncertainty. Many aspects of the design are the result of properties that are defined within some tolerances, of measurements that are appropriate, and of circumstances and environmental conditions that are out of their control. This uncertainty was typically handled by using factors of safety, and resulted in designs that may have been overly conservative. Therefore, understanding and handling the uncertainties is critical in improving the design, controlling …
Parametric Instabilities For Vibratory Energy Harvesting Under Harmonic, Time-Varying Frequency, And Random Excitations, Christopher Stabler
Parametric Instabilities For Vibratory Energy Harvesting Under Harmonic, Time-Varying Frequency, And Random Excitations, Christopher Stabler
All Theses
This effort investigates and evaluates the prospect of using parametric instabilities for vibratory energy harvesting. To that end, we consider a parametrically-excited piezoelectric cantilever beam and study its performance as an energy harvester under i) fixed-frequency harmonic excitations, ii) time-varying frequency excitations, and iii) band-limited Gaussian noise. In the case of fixed-frequency excitations, we use the Method of Multiple Scales to obtain approximate analytical expressions for the steady-state response amplitude and instantaneous output power in the vicinity of the first principle parametric resonance. We show that the electromechanical coupling and load resistance play an important role in determining the output …
Combined Musculo-Skeletal Multi-Body Dynamics/Finite Element Analysis Of Several Ergonomics And Bio-Mechanics Problems, Xin Xie
All Theses
Within this thesis, two ergonomics (i.e. seating comfort and long-distance driving fatigue problems) and two structural bio-mechanics (i.e. femur-fracture fixation and radius-fracture fixation) problems are investigated using musculo-skeletal multi-body dynamics and finite element computational analyses.
Within the seating comfort problem analyzed, a complete-body finite element model is constructed and used to assess the effect of seat geometry and seating posture on the feel of comfort experienced by a seated human.
Within the long-distance driving fatigue problem, musculo-skeletal analysis is employed to assess the extent of fatigue experienced by a driver through the evaluation of level of activity of his/her various …
Ultracapacitor Heavy Hybrid Vehicle: Model Predictive Control Using Future Information To Improve Fuel Consumption, Seneca Schepmann
Ultracapacitor Heavy Hybrid Vehicle: Model Predictive Control Using Future Information To Improve Fuel Consumption, Seneca Schepmann
All Theses
This research is concerned with the improvement in the fuel economy of heavy transport vehicles through the use of high power ultracapacitors in a mild hybrid electric vehicle platform. Previous work has shown the potential for up to 15% improvement on a hybrid SUV platform, but preliminary simulations have shown the potential improvement for larger vehicles is much higher.
Based on vehicle modeling information from the high fidelity, forward-looking modeling and simulation program Powertrain Systems Analysis Toolkit (PSAT), a mild parallel heavy ultracapacitor hybrid electric vehicle model is developed and validated to known vehicle performance measures. The vehicle is hybridized …
Non-Contact Spatially Constrained Optical Scanning Methods Applied For Depth, Width And Gap Measurements, Konda Reddy Thotti Reddy
Non-Contact Spatially Constrained Optical Scanning Methods Applied For Depth, Width And Gap Measurements, Konda Reddy Thotti Reddy
All Theses
The thesis presents the non-contact laser projection based systems utilized for quantifying the feature dimensions like width, depth and air gaps. Laser diode, Charge coupled device (CCD) and post-processing software using image processing tools are the major components of the non-contact measurement systems. The study involves two methods where the first method comprises of active laser-based triangulation and morphological edge detection for depth and width measurement applications. The second method uses edge detection technique and Dynamic Field of View (DFOV) for gap detection and tracking. Using the developed techniques, the case studies are conducted with smooth plastic fenders with induced …
Fuzzy Logic Approach To Stability Control, Jeffery Anderson
Fuzzy Logic Approach To Stability Control, Jeffery Anderson
All Theses
Traditional Electronic Stability Control (ESC) for automobiles is usually accomplished through the use of estimated vehicle dynamics from simplified models. Starting with the conventional two degree-of-freedom vehicle model, one can estimate the vehicle states from the driver steering input. From this estimate, vehicle sideslip angle can be found and this is generally used with a threshold value to initiate a control action. The input/output relationship of the model depends heavily on the accuracy of the parameters used and various means to correct model inaccuracies. Specifically, these models depend on the tire cornering stiffness which is prone to change with age …
Modeling And Optimization Of A Plug-In Hybrid Electric Vehicle, Venkat Vijay Kishore Turlapati
Modeling And Optimization Of A Plug-In Hybrid Electric Vehicle, Venkat Vijay Kishore Turlapati
All Theses
Today, the world is faced with a situation where new technologies have to be developed to decrease the dependence on natural non-renewable resources. Each day, as the demand for non-renewable resources increases, it puts great pressure on the scientific fraternity to develop new technologies that are aimed at reducing this dependence.
Today's road traffic plays a major part in the energy consumption worldwide. Hence it is imperative that we develop environmentally friendly solutions to this problem that arises in the transportation sector. Hybrid vehicle is one of the alternatives that can be seen as a viable solution to this energy …
Determination Of Higher Order Coefficients For A Crack Parallel To An Interface, Venkata Lakshman Kolluru
Determination Of Higher Order Coefficients For A Crack Parallel To An Interface, Venkata Lakshman Kolluru
All Theses
A general method based on the singular integral equations is developed to
computationally determine the higher order coefficients in mixed mode fracture
mechanics. These 'k' and 'T' coefficients are defined with respect to a polar coordinate
system centered at a crack tip, and give asymptotic expressions for stresses and
displacements according to the William's eigenfunction expansions,
(r, ) (2r) k f (n, ) k f (n, ) IIk
ij
II
n
Ik
ij
I
n
n 0
2
1
n
ij
1
(0, ) (2 ) ( , ) ( , …
Electromechanical Modeling And Analysis Of A Self-Excited Micro-Power Generator, Amin Bibo
Electromechanical Modeling And Analysis Of A Self-Excited Micro-Power Generator, Amin Bibo
All Theses
Micro-power generators (MPGs) are compact, scalable, and low-maintenance energy harvesting devices that capture and transform wasted ambient energy into electricity.
Such devices, which are currently being researched as a possible replacement for batteries, can act as a power source to maintain and allow autonomous operations of
remote low-power consumption sensors. This thesis introduces a novel MPG which transforms wind energy into electricity via wind-induced self-excited oscillations
of piezoelectric cantilever beams. The operation concept of the device is simple: similar to music-playing harmonica that create tones via oscillations of reeds when
subjected to air blow, the proposed device uses flow-induced self-excited …
Infrared Thermography And Ultrasonic Inspection Of Adhesive Bonded Structures, Overview And Validity, Suhas Vedula
Infrared Thermography And Ultrasonic Inspection Of Adhesive Bonded Structures, Overview And Validity, Suhas Vedula
All Theses
The work focuses on establishing a relationship between two different techniques of Nondestructive testing, namely Infrared Thermography and Ultrasonic Inspection. The integration of the two testing techniques is done with an expectation to achieve accurate characterization and determination of internal defects in adhesive bonded structures.
Experiments are done on sandwich samples with defects using various ultrasonic testing methods like pulse-echo and immersion techniques. The results thus obtained are documented and location of the defects is marked. The same samples are then tested using Infrared thermography to visualize the defects.
The results obtained by both the methods are compared to check …
Automation Of Non-Destructive Testing Techiniques Used For Finding Defects, Bhanu Singh
Automation Of Non-Destructive Testing Techiniques Used For Finding Defects, Bhanu Singh
All Theses
This master thesis focuses on the automation and fusion of non-destructive testing methods. The research includes the fusion of non-destructive testing methods done with infrared micro-bolometer and ultrasonic transducers. A control system which utilized mechanical, electrical, electronic systems and computer aided technologies was developed. Conveyor belt system, PLC (programmable logic controller), XYZ mechanism and different sensors were utilized to automate the process of capturing images and a communication link was set up between thermal camera and system that controls the ultrasonic testing apparatus, to integrate the two techniques. The test results from the thermal camera were utilized in ultrasonic testing. …
Induction Assisted Thermography For Inspection Of Micro Defects On Sheet Metals, Sree Pamidi
Induction Assisted Thermography For Inspection Of Micro Defects On Sheet Metals, Sree Pamidi
All Theses
The work focuses on Induction assisted Thermography as a non-contact and non-destructive method of Inspecting micro defects on sheet metals used for making automotive body panels. Induction heating as a source of excitation to elevate the temperatures of sheet metals for uniform heating and detect ability of the defect is the main objective of the study.
Experiments are done on sheet metal samples with defects using excitation techniques like Pulse and Electromagnetic Induction. The thermal images obtained from the infrared camera are used to quantitatively analyze the detect ability of defects on sheet metals. The limitations of using Pulse technique …
Design Method Development For The Design Of Traction Systems, Avinash Kolla
Design Method Development For The Design Of Traction Systems, Avinash Kolla
All Theses
The objective of this research is to develop a design method for rapid exploration of traction concepts primarily for off-road vehicles. Different approaches available to achieve this objective are discussed and compared, such as computational, analytical, and physical methods. Computational approaches are based on simulations performed using Finite Element Method (FEM), Discrete Element Method (DEM), and combined Finite Element-Discrete Element (FE-DE) methods. Analytical approaches are based on closed form mathematical models developed by previous researchers based on the theory of plasticity. Physical approaches include fabrication and testing of prototypes at different levels of abstraction. This thesis compares these different approaches …
Re-Engineering A Trash/Recycling Collection Vehicle Based On Challenging Customer Requirements, Edward Smith
Re-Engineering A Trash/Recycling Collection Vehicle Based On Challenging Customer Requirements, Edward Smith
All Theses
Engineering design starts with the definition of design requirements. These requirements define the design problem and must be satisfied for a solution to be acceptable. While many design methodologies exist for defining design requirements, none presently provides a systematic approach for designers to challenge requirements. Yet, Pahl and Beitz, Hazelrigg, and Suh all argue that a designer should continually question the need for each requirement and refine them as the product evolves. Thus, there exists a need to develop a comprehensive method that enables a designer to verify, review/question, and revise requirements throughout the design process. This research uses the …
Comprehensive Analysis Of A Student-Centered Active-Learning Integrated Statics And Dynamics Course For Mechanical Engineers, Marisa Orr
All Theses
The Student-Centered Active Learning in Undergraduate Programs (SCALE-UP) approach to instructional design was adapted with the goal of delivering more effective statics, dynamics and multivariate calculus instruction and integrated course curricula. Inquiry-based learning exercises were designed, incorporating material from statics and dynamics into multivariable calculus, and vice-versa, as well as integrating statics and dynamics into one course. Analysis included an exploration of student study habits, multiple measures of course effectiveness, and an examination of curricular effects. Challenges of implementation are also discussed.
Study habits of students in an integrated Statics and Dynamics course were assessed through a voluntary survey in …
Modeling Of A Porous Metal Foam Cryogenic Counter Flow Heat Exchanger, Craig Fortier
Modeling Of A Porous Metal Foam Cryogenic Counter Flow Heat Exchanger, Craig Fortier
All Theses
This thesis involves the modeling of cryogenic fluids through a porous metal foam counter flow heat exchanger. Although much research has been completed involving light weight high porosity metal foams in recent years, research performed on the subject of mid range porosities in metal foams and their use in heat exchangers has been relatively untouched. Even less literature is available pertaining to the effects of cryogenic fluids in porous metal foams.
Much about heat exchanger performance and pressure drop depends on the structure and relative density of the metal foams. This has been elaborated in several sources, but only for …
A Proposed Method To Identify Requirements Significant To Mass Reduction, James Mclellan
A Proposed Method To Identify Requirements Significant To Mass Reduction, James Mclellan
All Theses
Reducing the mass of engineering products holds the potential for significant benefits by reducing material costs, environmental impact, transportation costs, and in the case of vehicles, reducing fuel consumption. While there are many approaches for reducing mass, analyzing requirements has the greatest potential since requirements definition is the earliest phase of product development, where the most design freedom exists. This thesis proposes a requirement analysis method that identifies requirements that impact significant amounts of mass. The research hypothesis is: Engineering requirements can be represented and processed in a systematic manner and linked to physical components and systems, thus enabling mass …
Interpretability Analysis Of Function Structures At Various Levels Of Abstraction: A User Study, Jonathan Thomas
Interpretability Analysis Of Function Structures At Various Levels Of Abstraction: A User Study, Jonathan Thomas
All Theses
Function models are used during the conceptual design phase of the design process to model the intended use or objective of a product, independent of the products physical form. Function models also aid in guiding design activities such as generating concepts and allocating design team resources. Recent research efforts have focused on the formalization of functional models through a controlled vocabulary and archival of functional representations in computer-based repositories. However, the usefulness and interpretability of these function models has not been rigorously evaluated.
This thesis presents the results of two controlled user studies to ascertain the interpretability of functional representations …
Electrokinetic Manipulation Of Particles And Cells In Microfluidic Devices, Christopher Church
Electrokinetic Manipulation Of Particles And Cells In Microfluidic Devices, Christopher Church
All Theses
With the recent advancement in micro-fabrication technology, lab-on-a-chip devices have been developed in order to perform biological analysis through cell manipulation. Microchannels used in these lab-on-a-chip devices have been demonstrated to accurately perform many different cell manipulation techniques such as focusing, separation, trapping, and lysis. Although there are many methods available for these techniques, electrokinetics has been rapidly gaining popularity due to the simplicity of application and removal of the need for in channel micro-structures. This thesis studies the use of electrokinetic flow and accompanying phenomena in various structured microchannels to perform focusing, separation, trapping, and lysis of cells. Three …
System Modeling And Power Management Strategy For A Series Hydraulic Hybrid Vehicle, Sisay Molla
System Modeling And Power Management Strategy For A Series Hydraulic Hybrid Vehicle, Sisay Molla
All Theses
A hydraulic hybrid vehicle draws propulsion power from an internal combustion engine as its prime mover and a gas-charged hydro-pneumatic accumulator as its energy buffer. The accumulator serves the purposes of storing regenerated braking energy and supplementing engine power as determined by an on-board power management strategy. In the configuration known as a series hydraulic hybrid powertrain, the engine is mechanically decoupled from the vehicle's wheels thereby offering excellent opportunities for maximizing energy efficiency and reducing pollutant emissions.
This thesis dealt with the development of a causally interconnected, non-linear, dynamic model of a series hydraulic hybrid powertrain featuring independently controllable …
The Characterization Of Leadership Within Undergraduate Engineering Design Teams Through Case Study Analysis, Gary Palmer Ii
The Characterization Of Leadership Within Undergraduate Engineering Design Teams Through Case Study Analysis, Gary Palmer Ii
All Theses
The purpose of this research is to clearly define leadership that exists within engineering project teams. Leadership can be applicable to any field of study and is heavily researched in business management. Sources which review leadership classify this topic in reference to managerial styles, leadership types and styles, emotional intelligence, and work climate. However, there are few sources which define leadership specifically within engineering environments. The motivation of this research is driven by the absence of defining and observing consistency in engineering leadership through the research‟s experience in engineering teams. Existing leadership is defined in this research through conducting two …
Linguistic Analysis Of Natural Language Engineering Requirements, Carl Lamar
Linguistic Analysis Of Natural Language Engineering Requirements, Carl Lamar
All Theses
In engineering design, the needs of the customer are expressed through engineering requirement statements. These requirement statements are often expressed using natural language because they are easily created and read. However, there are several problems associated with natural language requirements including but not limited to ambiguity, incompleteness, understandability, testability and over specificity. Several representation and analysis tools have been proposed to address these problems within a requirement statement. These tools include formal languages, such as UML and SysML, requirement management tools, such as IBM Telelogic Doors, and natural language processors such as QuARS. These tools assist in the systematic elicitation …
User Study Of Information Extracted From Engineering Representations, Rachel Hannah
User Study Of Information Extracted From Engineering Representations, Rachel Hannah
All Theses
It is important for designers to understand the usefulness of different engineering representations in order to save time and money throughout a project. Designers often rely on past experience to decide which model to construct; yet students without this experience have no help. Interestingly there are noticeable gaps in the research literature with respect to how and when to select representations and modeling approaches for engineering designs. This thesis examines the differences between three types of engineering representations, specifically sketches, drawing packages, and physical prototypes. The amount of information designers can extract from these representations and also the correctness and …
The Effect Of A Surfactant Monolayer On Gas Exchange Across An Air-Water Interface During Mixed Convection, Richard Lee
The Effect Of A Surfactant Monolayer On Gas Exchange Across An Air-Water Interface During Mixed Convection, Richard Lee
All Theses
A set of laboratory experiments are presented that reveal the effect of a surfactant monolayer on the transport of oxygen across an air-water interface during mixed convection conditions. The experiments were conducted in a wind/water tunnel with water tanks of differing depth. Forced convection was imposed via the air flow, while natural convection was imposed by heating the water bulk above the air temperature. For the range of wind speeds being considered, mixed convection conditions resulted. Experiments were also conducted with only forced convection present. The data acquired during these experiments were used to develop a parameterization between the Sherwood …
Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal
Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal
All Theses
The purpose of this research is to determine the optimum process parameters for the Precision Glass Molding (PGM) Process using Manufacturing Design, Design of Experiments and Metrology (for measuring the geometry of lenses). First, a custom machine is designed and manufactured which can carry out Precision Glass Lens Molding Experiments. This machine is then modified to improve temperature, position and force control. A literature review is performed to obtain data for process parameters that have been used in previous PGM studies. The collected data is then used in Design of Experiments to create twenty seven experiments that determine the optimum …
Principal Component Thermography For Steady Thermal Perturbation Scenarios, Rohit Parvataneni
Principal Component Thermography For Steady Thermal Perturbation Scenarios, Rohit Parvataneni
All Theses
The work focuses on the qualitative enhancement of Thermographic Inspection data using Principal Component Analysis technique. A new processing tool named Economical Singular Value Decomposition (SVD) is proposed for analyzing the infrared image sequences acquired from the test specimen.
Experiments are carried out on test sample using thermal excitation modalities such as flash, halogen and induction to create temperature variations. The infrared (IR) image sequence containing the information about the sample is captured using IR cameras. The acquired IR image sequences are processed using the proposed Economical SVD which projects the matrix of raw pixel values of image sequence into …
Modeling The Cooling Phase Of The Lens Molding Process, Saravanan Kannan
Modeling The Cooling Phase Of The Lens Molding Process, Saravanan Kannan
All Theses
The lens molding process is a relatively new technique used to manufacture lenses, in particular, high precision aspheric lenses. In order to achieve the desired size and shape of the lens, the cooling process after pressing must be controlled precisely because of the time and temperature dependent viscoelastic behavior of glass near and below the molding temperature. This thesis gives a detailed description of a three-dimensional computational model for analyzing the cooling phase of the lens molding process. Conduction, convection and radiation are considered in the model by coupling a computational fluid dynamics analysis of the flow of nitrogen through …
Experimental Characterization Of Stress Relaxation In Glass, Hemanth Kadali
Experimental Characterization Of Stress Relaxation In Glass, Hemanth Kadali
All Theses
Glass viscoelasticity has gained importance in recent years as glass lens molding appeared as a valuable alternative to the traditional grinding and polishing process for manufacturing glass lenses. In the precision lens molding process, knowledge of viscoelastic properties of glass in the transition region, which affect the stress relaxation behavior, is required to precisely predict the final size and shape of molded lenses. The purpose of this study is to establish a step-by-step procedure for characterizing the viscoelastic behavior of glass in the glass transition region using a finite term Prony series of a Generalized Maxwell model. This study focuses …
Charging Kinetics Of Electric Double Layer Capacitors, Clint Cagle
Charging Kinetics Of Electric Double Layer Capacitors, Clint Cagle
All Theses
A recent increase in the popularity of EDLCs and AC-EOF has necessitated a deeper understanding of the structure and charging kinetics of electrical double layers (EDLs) at electrode-electrolyte interfaces. Here, the charging kinetics of EDLs in nanoscale EDLCs is studied by a circuit model, a Poisson-Nernst-Planck (PNP) mo del, and molecular dynamics (MD) simulations. The results of the MD simulations demonstrate a linear charging behavior of EDLs near planar electrodes for both aqueous and organic electrolytes at charging below 90% and time larger than tens of picoseconds. Additionally, we will show that the circuit and PNP models are capable of …