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Articles 1 - 30 of 30
Full-Text Articles in Mechanical Engineering
An Early Warning Monitoring System For Cnc Spindle Bearing Failure, Andrew Werner
An Early Warning Monitoring System For Cnc Spindle Bearing Failure, Andrew Werner
All Theses
Equipment employed in a manufacturing environment must be able to operate as long as possible having as little downtime as possible. Therefore, maintenance is crucial in order to allow for the equipment to perform its designated tasks without failure, especially on critical systems. In a CNC machine, if the spindle fails, the machine is useless. Having the ability to detect spindle degradation to the point where a replacement spindle installation can be planned, via condition monitoring, is invaluable to a manufacturer who utilizes these types of machines.
An early warning monitoring system for CNC spindle bearing failure has been developed …
Product And Process Based Assembly Time Estimation In Engineering Design, Michael Miller
Product And Process Based Assembly Time Estimation In Engineering Design, Michael Miller
All Theses
This thesis presents the research and development of two assembly time estimation techniques for the automotive industry. Both of these techniques are capable of being implemented early in the product life-cycle of a vehicle and require information available in this phase. Currently, assembly time estimation is performed after production has begun and is a tedious manual process requiring hours of motion-time method studies for each assembly activity. The techniques proposed in this thesis can both be performed prior to the start of production and are capable of being performed automatically after the initial mapping.
The first assembly time estimation technique …
In Vitro Study Of Fluid Diodes In The Pulmonary Valve Position, John Porcher
In Vitro Study Of Fluid Diodes In The Pulmonary Valve Position, John Porcher
All Theses
Every year many people suffer from severe chronic pulmonary insufficiency. Problems that can be incurred include the valve becoming stenotic, where it inhibits antegrade flow, and incompetent, allowing retrograde flow. When either of these conditions occurs with great severity, it is often necessary for the native valve to be replaced. There are no acceptable, permanent solutions currently available for a pulmonary valve replacement. Previous research, based on regurgitant fraction and transvalvular gradient, has indicated that a fluid diode could possibly serve as a permanent valve replacement solution. This study investigated the effectiveness of a diode to reduce the workload of …
Fabrication And Characterization Of Multi-Functional Non-Spherical Particles Via Mechanical Deformation, Venkata Shilpa Varahagiri
Fabrication And Characterization Of Multi-Functional Non-Spherical Particles Via Mechanical Deformation, Venkata Shilpa Varahagiri
All Theses
Nanoparticles bridge the gap between bulk materials and molecules. They possess exciting but contrasting mechanical, chemical, magnetic and optical properties when compared to their bulk counterparts due to their shape and size. When the size of noble metal nanoparticles is reduced to less than the wavelength of light, the particles intensely absorb and scatter light at wavelengths that depend on the particle size, shape, and local dielectric environment due to Localized Surface Plasmon Resonance (LSPR) modes. Recently, plasmonic particles have been used in a wide variety of sensor and optical device applications including immunoassays and surface enhanced Raman spectroscopy substrates. …
Laminar Flame Speed Estimation From Experimental Data Using A Quasi-Dimensional Turbulent Flame Entrainment Combustion Simulation For Spark Ignition Engines, Akash Desai
All Theses
The goal of this research is to develop a thermodynamic simulation of spark-ignition engine combustion that uses a predictive burn-rate model. Previously done thermodynamic engine simulations in MATLAB are based on a specified burn rate model. Also, the effect of turbulence parameters on the rate of mass burn up is not considered. A predictive burn rate model is necessary to study the effect of different fuels on spark ignition engine combustion. The effect of laminar flame speed and turbulent intensity on combustion is difficult to assess experimental due to the difficulty in the measurement of these two variables. Thus, the …
Modeling, Finite Element Analysis, And Optimization Of Non-Pneumatic Tire (Npt) For The Minimization Of Rolling Resistance, Mallikarjun Veeramurthy
Modeling, Finite Element Analysis, And Optimization Of Non-Pneumatic Tire (Npt) For The Minimization Of Rolling Resistance, Mallikarjun Veeramurthy
All Theses
Recently, the development of non-pneumatic tires (NPT) such as the Michelin Tweel is receiving increased attention due to potential advantages over pneumatic tires such as low mass, no run flat, good contact pressure distribution, and low rolling resistance (RR). This study focuses on the design of a NPT based on properties of vertical stiffness, contact pressure, and rolling energy loss. Using a finite element (FE) model, a parametric study is conducted to study the effect on vertical stiffness, contact pressure, and rolling resistance (RR) response considering three design variables: (1) thickness of the spokes, (2) the shear band thickness, and …
Constrained Layer Damping Of Honeycomb Composite Structures, Rohit Telukunta
Constrained Layer Damping Of Honeycomb Composite Structures, Rohit Telukunta
All Theses
Composite sandwich structures have replaced homogenous dense solids in many applications due to their advantages of high stiffness to weight ratio, and higher damping characteristics. Higher damping in engineering applications is desirable to reduce structural vibrations. The application of a viscoelastic layer between two thin face sheets gives rise to the concept of constrained layer damping which is an effective technique to achieve increased damping in engineering applications.
Honeycomb cellular structures are often used for the core in sandwich construction because of their low density and high stiffness properties. Regular honeycombs are defined by conventional hexagonal geometry, which gives rise …
A Priori Analysis Of Subgrid-Scale Heat Flux Vectors In High Pressure H2/O2 Mixing And Reacting Shear Layers, Ayse Korucu
A Priori Analysis Of Subgrid-Scale Heat Flux Vectors In High Pressure H2/O2 Mixing And Reacting Shear Layers, Ayse Korucu
All Theses
A Direct Numerical Simulation (DNS) database of supercritical, transitional H2/O2 mixing and reacting shear layers is analyzed in an a priori manner to obtain subgrid statistics relevant to Large Eddy Simulation (LES) engineering modeling. The DNS employs a real gas state equation, detailed chemistry, accurate property models, multicomponent, differential, and cross diffusion. The parallel simulations were conducted using eighth order central finite differencing in conjunction with a fourth order accurate Runge-Kutta time integration, on resolutions up to 135 million grid points, and used up to 2,016 processing cores. All simulations are for an ambient pressure of 100 atm and are …
Molecular Dynamics Study Of Particle Impact Induced Bond Breaking Of Single-Walled Carbon Nanotubes And Quality Factors Of Nanocomposite Structures, Puroorava Annapaneni
Molecular Dynamics Study Of Particle Impact Induced Bond Breaking Of Single-Walled Carbon Nanotubes And Quality Factors Of Nanocomposite Structures, Puroorava Annapaneni
All Theses
Part A
Injection of particles to the side wall of single-walled carbon nanotubes (SWCNT) has been employed for doping and storage of particles on SWCNTs. In addition, particle bombardment can be used to cut and modify graphene structures. While the collision of hydrogen atoms with SWCNTs has been extensively studied, collision dynamic behavior of heavy particles with SWCNTs has not been well understood. To facilitate a better understanding of the particle-SWCNT collision process, in this work, we study the impact of five noble gas atoms (He, Ne, Ar, Kr, Xe) with SWCNTs and investigate particle impact induced CNT bond breaking …
Computational Analysis Of The Dynamic Forces In Drive Train Components Of An Offshore Wind Turbines, Artem Korobenko
Computational Analysis Of The Dynamic Forces In Drive Train Components Of An Offshore Wind Turbines, Artem Korobenko
All Theses
Wind has good potential for contributing to the national energy supply. Offshore sites and deep sea locations can be especially attractive as the wind turbine market grows. In such places larger wind resources are available with reduced turbulence intensity and wind shear. In addition, visual impact along with noise aspects are reduced. Offshore siting requires greater attention to structural stability and endurance. Forces on drive train components, such as the bearing system, are not well understood.
This work presents the development a model that calculates dynamical forces in drive train components of off-shore wind turbines. The model of a 5MW …
Injection Molding Of Micro-Features, Manjesh Dubey
Injection Molding Of Micro-Features, Manjesh Dubey
All Theses
A method for creating regular arrays of surface features in the 10µm to 200µm range over large areas in metallic materials enables the use of treated surfaces on injection molds. This surface control is used for manufacturing products with controllable optical, tribological, heat transfer, and surface tension properties. However, the flow, filling, and solidification behavior of molten polymer at the micro scale is not well understood.
Therefore, the purpose of this study is to understand the formation of micro-structure on a polymer surface and derive a range of robust solutions for injection molding of these micro-featured surfaces. This study uses …
A Method For Evaluating Manufacturing Change In Engineering Design, Christopher Brooks
A Method For Evaluating Manufacturing Change In Engineering Design, Christopher Brooks
All Theses
Design changes are a frequent occurrence over the life of a product that may be initiated by an update to the product functionality, new customer needs, or generational improvements. The costs associated with these changes are undesirable, and are often times greatly inflated by additional, unanticipated changes that result from change propagating throughout the system. Propagation paths occur when an initiating change to a component necessitates subsequent changes to coupled components, as the change continues to propagate throughout the product architecture. The nature of this change propagation is challenging to characterize and accurately predict. To address this issue, a change …
Extracting Depth Information From Stereo Vision System, Using A Correlation And A Feature Based Methods, Mahmoud Abdelhamid
Extracting Depth Information From Stereo Vision System, Using A Correlation And A Feature Based Methods, Mahmoud Abdelhamid
All Theses
This thesis presents a new method to extract depth information from stereo-vision acquisitions using a feature and a correlation based approaches. The main implementation of the proposed method is in the area of Autonomous Pick & Place, using a robotic manipulator. Current vision-guided robotics are still based on a priori training and teaching steps, and still suffer from long response time.
The study uses a stereo triangulation setup where two Charged Coupled Devices CCDs are arranged to acquire the scene from two different perspectives. The study discusses the details of two methods to calculate the depth; firstly a correlation matching …
Understanding The Role Of Functions And Interactions In The Product Design, Raveesh Ramachandran
Understanding The Role Of Functions And Interactions In The Product Design, Raveesh Ramachandran
All Theses
Engineering designers often generate design concepts based on a functional understanding of the problem. Many engineering textbooks encourage designers to abstract the essential problem to a higher-level functional representation of the product and subsequently develop solutions to the functional needs. However, a functional perspective of design does not provide a complete view of what the product must do and how the product must interact with users and other parts. To address this, an alternative modeling approach has been developed to complement the traditional functional modeling approaches. Two such approaches include (1) activity modeling to capture the user actions from production …
Cfd Analysis Of The Under Hood Of A Car For Packaging Considerations, Sreekanth Reddy Gondipalle
Cfd Analysis Of The Under Hood Of A Car For Packaging Considerations, Sreekanth Reddy Gondipalle
All Theses
In recent years, there has been an increase in demand towards the improvement of car design for achieving better performance and increasing passenger comfort. Improving the design of individual components to meet the customer needs for improved vehicle performance alone is not enough. Interactions of these components with the surrounding components and their placement should also be investigated. Placement of these components in the under hood space forms a 3-Dimensional packaging problem. In the past, a multi objective optimization process was setup to determine the optimal placement of these components in the car under hood space. Three main objectives were …
A Priori Analysis Of Subgrid-Scale Pressure In High Pressure H2/O2 Mixing And Reacting Shear Layers, Zhiyuan Ma
A Priori Analysis Of Subgrid-Scale Pressure In High Pressure H2/O2 Mixing And Reacting Shear Layers, Zhiyuan Ma
All Theses
An a priori analysis of subgrid-scale pressure in high pressure combustion is carried out using three different flow fields obtained by direct numerical simulation (DNS). The simulations directly solve the Navier-Stokes equations of high pressure, transitional H2/O2 mixing and reacting shear layers employing a cubic Peng-Robinson real gas state equation. Detailed chemistry, multicomponent, differential, and cross diffusion are included. The results are analyzed to provide subgrid information relevant to Large Eddy Simulation (LES) of turbulent combustion. The analysis includes a detailed comparison of the actual filtered pressure with its corresponding form evaluated with the filtered primitive variables. …
Modeling And Finite Element Alaysis Of Fluid Structure Interaction In A Wind Energy Harvester, Bargav Cheruku
Modeling And Finite Element Alaysis Of Fluid Structure Interaction In A Wind Energy Harvester, Bargav Cheruku
All Theses
An energy harvesting system inspired by musicplaying harmonicas was developed for microwind power generation. The energy harvester uses flow-induced self-sustained oscillations of a piezoelectric beam embedded within a chamber to generate electric power. While the power generation capability of the energy harvester has been demonstrated previously, there is a lack of understanding behind the basic physics of the driving mechanism responsible for the self-sustained oscillations. In addition, the performance of the nonlinear multi-physics system with strong fluid and structure coupling depends on many physical and design parameters. A systematic study on the effects of these parameters is necessary for the …
Model-Based System Fault Diagnosis Utilizing Adaptive Threshold With Application To Automotive Electrical Systems, Ali Hashemi
Model-Based System Fault Diagnosis Utilizing Adaptive Threshold With Application To Automotive Electrical Systems, Ali Hashemi
All Theses
Recent advancement in the field of automotive industry is largely due to the addition of electrical and electronic equipment; some of the safety features in the vehicle and advanced driver assistance systems are examples of such equipment. Furthermore, safe operation of the vehicle is highly dependent on the electrical power generation and storage system (EPGS). Therefore, to ensure optimal operation of this system, a reliable diagnosis of the system is essential. However, as the complexity of the electrical systems has increased, the identification of a malfunction has become an increasingly difficult task to handle.
In the current work, a model-based …
Friction Stir Welding (Fsw) Process Modeling And Fsw Joint Design For Blast Survivable Structures, Anand Hariharan
Friction Stir Welding (Fsw) Process Modeling And Fsw Joint Design For Blast Survivable Structures, Anand Hariharan
All Theses
In order to satisfy the need for better ballistic performance against lethal threats, new grades of Titanium (e.g. Ti-6Al-4V) and Aluminum (e.g. AA5083) alloys are being employed in the design of blast survivable structures. These better performing alloys are not readily amenable to conventional welding process or result in inferior welds when joined using conventional welding process. On the other hand, Friction Stir Welding (FSW), a relatively new welding process, has been found to be successful in producing good quality welds in these alloys. FSW also offers better weld performance in comparison with the conventional welding process. But the methodology …
Analytical Solutions Using High Order Composite Laminate Theory For Honeycomb Sandwich Plates With Viscoelastic Frequency Dependent Damping, Nan Shan
All Theses
Analytical methods allow parametric changes in geometric and material properties of a honeycomb sandwich plate for studies of stiffness, mass, and damping characteristics with low computational cost. However, studies based on analytical methods are still limited with frequency independent damping models. Specifically, previous analytical models have not consider the frequency dependent damping for viscoelastic honeycomb core sandwich composites, while some work has been done on studying the honeycomb sandwich plate using finite element method, which can be computationally expensive for multiple parameter studies. Therefore, in this work, the honeycomb sandwich plate is studied analytically based on the cellular material theory, …
Viscoelastic Damping Of Hexagonal Honeycomb Sandwich Panels, Nikhil Seera
Viscoelastic Damping Of Hexagonal Honeycomb Sandwich Panels, Nikhil Seera
All Theses
Composite sandwich structures with a viscoelastic core material constrained between thin stiff face sheets are an effective means of damping in engineering applications. Damping introduces energy dissipation which helps control vibration amplitudes. Conventional Hexagonal honeycombs are often referred to as regular honeycombs and are defined by cellular geometry with effective positive Poisson's ratio. Regular honeycombs are commonly used for the cores of sandwich plates because of their low density and high stiffness properties. Honeycombs with negative in-plane Poisson's ratio are known as Auxetic honeycombs and offer enhancement of mechanical properties such as impact absorption, damage resistance, when compared to regular …
Joule Heating Effects On Electrokinetic Transport In Constriction Microchannels, Sriram Sridharan
Joule Heating Effects On Electrokinetic Transport In Constriction Microchannels, Sriram Sridharan
All Theses
Microfluidic technology involving multidisciplinary studies including MEMS, chemistry, physics, fluids and heat transfer has been developed into a promising research field in the recent decade. If offers many advantages over conventional laboratory techniques like reduced reagent consumption, faster analysis, easy fabrication and low chemical waste. Microfluidic lab-on-a-chip devices have been used to manipulate cells and particles like sorting, separating, trapping, mixing and lysing. Microfluidic manipulation can be achieved through many methods and insulator based dielectrophoresis (iDEP) is one of the highly used method in the recent years. In iDEP, both DC and AC voltages can be applied to the remote …
Finite Element Analysis Prediction Of Stresses In H.L. Hunley Submarine By Global-To-Local Model Coordination, Aditya Sai Nag Choragudi
Finite Element Analysis Prediction Of Stresses In H.L. Hunley Submarine By Global-To-Local Model Coordination, Aditya Sai Nag Choragudi
All Theses
H.L Hunley was a submarine of the Confederate States of America that participated in the American Civil War. On February 17, 1864, H.L.Hunley created history by becoming the first submarine to sink a enemy ship after its attack on USS Houstanic. After Hunley never returned to the shore and the details of its wreck were unknown. On August 8, 2000, H. L Hunley was brought to the surface after 136 years of its wreckage. The submarine is currently at the Warren Lasch Conservation Center located in Charleston.
This study focuses on the structural analysis of the H.L Hunley submarine to …
Modeling And Finite Element Analysis Methods For The Dynamic Crushing Of Honeycomb Cellular Meso-Structures, Jesse Schultz
Modeling And Finite Element Analysis Methods For The Dynamic Crushing Of Honeycomb Cellular Meso-Structures, Jesse Schultz
All Theses
The effective static mechanical properties, such as the moduli of elasticity and rigidity and Poisson's ratio, of honeycomb cellular meso-structures are capable of control due to variations of their cellular geometry. While the dynamic properties of these structures are a popular topic of research, there is a lack of both consistent modeling methods and generalizations in terms of honeycomb cellular geometry. In order to fill these gaps, this study presents a standard set of methods for the finite element analysis (FEA) of honeycomb cellular materials subject to dynamic loading conditions, as well as illustrates the effects of the cellular geometry …
Connective Complexity Methods For Analysis And Prediction In Engineering Design, James Mathieson
Connective Complexity Methods For Analysis And Prediction In Engineering Design, James Mathieson
All Theses
Complexity is an aspect of engineering design that is often addressed directly with the principle that 'designs should be simple'. However, such a principle fails to offer an effective means of quantifying the complexity of a given design for comparison and decision making. The measurement of complexity within a specific representations and domains has been well established. However, such measurements are inherently limited in their applicability and not always clear in their implications. This research presents a method of measuring complexity from different engineering representations in a consistent manner and explores the application of these measures.
The development of a …
Requirements Determination Of A Novel Non-Pneumatic Wheel Shear Beam For Low Rolling Resistance, Niranjan Thyagaraja
Requirements Determination Of A Novel Non-Pneumatic Wheel Shear Beam For Low Rolling Resistance, Niranjan Thyagaraja
All Theses
The hysteretic loss associated with cyclic shear in the elastomeric shear layer is one of the prevailing concerns for the development of a low rolling loss non-pneumatic wheel. We propose to eliminate the hysteretic losses associated with the elastomeric shear layer and thus, reduce the corresponding rolling resistance by using linear elastic materials which are inherently non-hysteretic. Since the shear modulus of a viscoelastic shear layer is less than that of an elastic material by several orders of magnitude, the challenge to achieve a low effective shear modulus shear layer with linear elastic materials directs towards the development of a …
Agent-Based Under Hood Packing, Karthik Ravindranath
Agent-Based Under Hood Packing, Karthik Ravindranath
All Theses
Improving vehicle performance and passenger comfort has been a prime engineering concern and focus of research for many years in automotive design. Turning to high-performance components in an effort to improve vehicle performance alone is often not enough and their placement and interactions with other components should also be an integral part of the improvement process. With the advancement in hybrid electric vehicle technology, the packing of components under the hood is ever more essential and challenging. Under hood packing is a multi-objective optimization problem with many, and mostly conflicting objectives. A non-deterministic multi-objective evolutionary algorithm needs to be integrated …
Evaluation Of Biomass And Coal Briquettes For A Spreader Stoker Boiler Using An Experimental Furnace - Modeling And Test, Gavin Wiggins
Evaluation Of Biomass And Coal Briquettes For A Spreader Stoker Boiler Using An Experimental Furnace - Modeling And Test, Gavin Wiggins
All Theses
The compliance of coal-fired boilers with emissions regulations is a concern for many facilities. The introduction of biomass briquettes in industrial boilers can help to reduce greenhouse gas emissions and coal usage. In this research project, a thermodynamic chemical equilibrium model was derived and analytical simulations performed for a coal boiler system for several types of biomass fuels such as beech, hickory, maple, poplar, white oak, willow, sawdust, torrefied willow, and switchgrass. The biomass emissions were compared to coal and charcoal emissions. The chemical equilibrium analysis numerically estimated the emissions of CO, CO2, NO, NO2, N2O, SO2, and SO3. When …
Multi-Scale Modeling Of The Fontan Circulation Using A Mock Circulatory System, John Chiulli
Multi-Scale Modeling Of The Fontan Circulation Using A Mock Circulatory System, John Chiulli
All Theses
The Fontan circulation is the result of a series of operations performed to save the lives of children born with univentricular circulations. The Fontan procedure achieves venous return to the pulmonary circulation without a ventricular power source. The load on the heart is reduced to normal, and these patients can lead a normal life into adulthood, although late complications continue to prevent normal lifespan. A unique feature of the Fontan circulation is the dependency of inferior vena cava flow on respiration. The Fontan circulation has been modeled experimentally using an adjustable mock circulatory system, which for the first time includes …
Parametric Amplification In The Context Of Vibratory Energy Harvesting, Roger Bode
Parametric Amplification In The Context Of Vibratory Energy Harvesting, Roger Bode
All Theses
Using a vibratory energy harvester (VEH) to independently power a sensor has become an increasingly popular topic due to the small amount of power current sensors require to operate. This can be achieved by scavenging energy from the ambient environment where the sensor is located. Numerous linear and nonlinear energy harvesters have been proposed in order to deal with various vibratory environments, along with improving the power production and/or bandwidth of the device.
In this thesis, we propose a technique to harvest energy from excitation sources that possess two frequency components: a fundamental component with large energy content, and a …