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Articles 91 - 113 of 113
Full-Text Articles in Engineering Mechanics
A Hydraulic Actuated Thermal Management System For Large Displacement Engine Cooling Systems, Peyton Frick
A Hydraulic Actuated Thermal Management System For Large Displacement Engine Cooling Systems, Peyton Frick
All Theses
The performance of automotive cooling systems can be improved by replacing the traditional mechanically driven radiator fan and water pump assemblies with computer controlled components. The introduction of electric servo-motors to drive the cooling components can improve temperature tracking, which should increase fuel efficiency and decrease tailpipe emissions. However, the power requirement for these electric motors increases with greater cooling demands if the radiator surface area remains constrained. For heavy-duty applications, where engines are subjected to significant cooling loads, electric motors may become impractical due to their increased size and power requirements; in these situations, hydraulic-based components are advantageous due …
Simulation Of A Backrest Moment Test For An Automotive Front Seat Using Nonlinear Contact Finite Element Analysis , Abhinand Chelikani
Simulation Of A Backrest Moment Test For An Automotive Front Seat Using Nonlinear Contact Finite Element Analysis , Abhinand Chelikani
All Theses
Computer aided engineering and finite element simulation are essential in order to predict accurately the safety performance of automotive structures in an event of crash. In this work, finite element simulation is used to evaluate the strength and deflection characteristics of a reference automotive front seat in an event of vehicle rear impact. Understanding the strength-deflection characteristics of front automotive seats during vehicle rear impact is important to ensure the safety function of the seat. The safety function is measured based on a moment test in accordance with government (ECE R17) regulations. Accurate finite element modeling of a reference seat …
Exact Solution Of Time History Response For Dynamic Systems With Coupled Damping Using Complex Mode Superposition, Manoj Kumar Chinnakonda
Exact Solution Of Time History Response For Dynamic Systems With Coupled Damping Using Complex Mode Superposition, Manoj Kumar Chinnakonda
All Theses
An exact solution method for general, non-proportional damping time history response for piece-wise linear loading proposed by Dickens is generalized to piece-wise quadratic loading. Comparisons are made to Trapezoidal and Simpson's quadrature rules for approximating the time integral of the weighted generalized forcing function in the exact solution to the decoupled modal equations arising from state-space modal analysis of linear dynamic systems. The time integral of the forcing function is recognized as a weighted integral with complex exponential and the general update formulas are derived using polynomial interpolation to the forcing function. Closed-form expressions for the weighting parameters in the …
Registration Using Graphics Processor Unit, Koushik Aravalli
Registration Using Graphics Processor Unit, Koushik Aravalli
All Theses
Data point set registration is an important operation in coordinate metrology. Registration is the operation by which sampled point clouds are aligned with a CAD model by a 4X4 homogeneous transformation (e.g., rotation and translation). This alignment permits validation of the produced artifact's geometry. State-of-the-art metrology systems are now capable of generating thousands, if not millions, of data points during an inspection operation, resulting in increased computational power to fully utilize these larger data sets. The registration process is an iterative nonlinear optimization operation having an execution time directly related to the number of points processed and CAD model complexity. …
Nonlinear Modeling Of The Adsorption-Induced Surface Stress In Piezoelectrically-Driven Microcantilever Biosensors, Mana Afshari
Nonlinear Modeling Of The Adsorption-Induced Surface Stress In Piezoelectrically-Driven Microcantilever Biosensors, Mana Afshari
All Theses
Microcantilever-based biosensors are rapidly becoming an enabling sensing technology for a variety of label-free biological applications due to their extreme applicability, versatility and low cost. These sensors operate through the adsorption of species on the functionalized surface of microcantilevers. The adsorption of biological species induces surface stress which originates from the molecular interactions such as adhesion forces of attraction/repulsion, electrostatic forces or the surface charge redistribution of the underlying substrate. This surface stress, consequently, alters the resonance frequency of the microcantilever beam.
This study presents a general framework towards modeling resonance frequency changes induced due to the surface stress arising …
Development Of A Microscopic Moirž Interferometry System, Jeremy Brougher
Development Of A Microscopic Moirž Interferometry System, Jeremy Brougher
All Theses
The human tooth is an amazing structure that is worthy of detailed research and analysis. For over half a century, various tests have been conducted to acquire more information about the structural and material properties of dentin, enamel, and the dentin-enamel junction. Unfortunately, variations still exist in the experimental results, even in the most recently collected data. The primary focus of the majority of material property testing on human teeth has been hardness testing utilizing indentation and nanoindentation analysis. However, several limitations still exist with the indentation technique. Thus, the moirŽ fringe analysis method, specifically microscopic moirŽ interferometry, has been …
Analyzing Relationships Between Lightning And Rain In Order To Improve Estimation Accuracy Of Rain , Justin Lapp
Analyzing Relationships Between Lightning And Rain In Order To Improve Estimation Accuracy Of Rain , Justin Lapp
All Theses
The remote estimation of rainfall rate R is essential for the aviation industry, agriculture, and food warning. Radar, the current means of R estimation, is not available in much of the world. In addition, this measurement involves a level of inaccuracy. Using lightning to detect rain is a relatively inexpensive alternative to radar systems and can be done from existing satellites. Previous research has revealed correlations between lightning and rain, suggesting either that it is possible to estimate R using lightning, or that it is possible to use it to correct for a portion of the radar inaccuracies. These correlations …
Advanced Thermal Management For Internal Combustion Engines, Thomas Mitchell
Advanced Thermal Management For Internal Combustion Engines, Thomas Mitchell
All Theses
The automotive cooling system has unrealized potential to improve internal combustion engine performance through enhanced coolant temperature control and reduced parasitic losses. Advanced automotive thermal management systems use controllable actuators (e.g., smart thermostat valve, variable speed water pump, and electric radiator fan) in place of conventional mechanical cooling system components to improve engine temperature tracking over most operating ranges. To optimize advanced cooling system performance, the electro-mechanical actuators must work in harmony to control engine temperature. The design and placement of cooling components should also be considered when attempting to maximize the performance.
In this research project, two distinct vehicle …
Design And Development Of An In-House Scanning Tunneling Microscope System, Esvar Subramanian
Design And Development Of An In-House Scanning Tunneling Microscope System, Esvar Subramanian
All Theses
ABSTRACT
The invention of Scanning Tunneling Microscope (STM) by Binnig and Rohrer in 1982 eliminated the use of optical lenses and replaced the conventional optical microscopes with a new class of microscopes called the Scanning Probe Microscopes (SPM). Because of their unique characteristics such as higher resolution and acquisition of nano level images without affecting the physical properties of the sample, they have found wide applications in a variety of scientific disciplines such as biology, material science and electrochemistry. After considerable advancements in instrumentation, the STM has evolved as a nanomanipulation and nanofabrication tool. It operates in two modes: constant …
Optimal Placement Of Metal Foils In Ultrasonic Consolidation Process, Raji Rexavier
Optimal Placement Of Metal Foils In Ultrasonic Consolidation Process, Raji Rexavier
All Theses
Ultrasonic Consolidation is a combination of additive and subtractive
manufacturing processes resulting in considerable material waste. This waste is a
function of the geometry of the part being manufactured and of the relative
placement of the layer with respect to the metal bands. Thus the waste may be
minimized by careful choice of the layer angle and offset from the original
position.
Previous work done in this field had developed an automated algorithm which
optimally places and orients the individual slices of the STL file of the artifact
being manufactured. However, the problem was solved on a 2-D scale and …
Real Time Prognostic Strategies Application To Gas Turbines, Rajat Sekhon
Real Time Prognostic Strategies Application To Gas Turbines, Rajat Sekhon
All Theses
Gas turbines are increasingly deployed throughout the world to provide electrical and mechanical power in consumer and industrial sectors. The efficiency of these complex multi-domain systems is dependant on the turbine's design, established operating envelope, environmental conditions, and maintenance schedule. A real-time health management strategy can enhance overall plant reliability through the continual monitoring of transient and steady-state system operations. The availability of sensory information for control system needs often allow diagnostic/prognostic algorithms to be executed in a parallel fashion which warn of impending system degradations. Specifically, prognostic strategies estimate the future plant behavior which leads to minimized maintenance costs …
Modeling Requirements Propagation To Generate Solutions For Minimizing Mass, Thulasiram Ezhilan
Modeling Requirements Propagation To Generate Solutions For Minimizing Mass, Thulasiram Ezhilan
All Theses
This thesis investigates the issue of weight reduction in moderately complex systems by addressing how to cascade the requirements to the individual components. Though mass can be reduced using different techniques such as material substitution or structural optimization; a systematic method for allocating mass as a function of requirements is necessary to provide novel alternate solutions that enable reduction of mass of the system while satisfying the requirements and tests governing them. Such a method can be developed by exploring different aspects of achieving weight reduction through change propagation in the parameters/elements governing the system. Though efforts have been made …
Temperature Control Of An Air Shower, Vedik Bobba
Temperature Control Of An Air Shower, Vedik Bobba
All Theses
Accuracy and repeatability in measurement is a primary concern in improving and maintaining the quality of a product in an industry. In the case of coordinate measuring machines, these factors are affected due to the ambient conditions. Specifically, change in temperature affects machine geometry and causes positioning errors. As a result, temperature and humidity control inside the housing has become an important and integrated concern of measuring machine. This research concentrates on the modeling, design, control and validation of an air shower to meet a 20 ± 0.1 ¼C specification.
The optimum performance of the control of temperature of air …
Analysis Of Ride Quality Of Tractor Semi-Trailers, Christopher Spivey
Analysis Of Ride Quality Of Tractor Semi-Trailers, Christopher Spivey
All Theses
This thesis develops parameter variation techniques for calculating the set of vehicle parameters that result in the best ride comfort for the driver. The model is a fifteen degree-of-freedom (15 DOF) tractor semi-trailer vertical dynamic ride model. The modeling and simulation techniques used in this thesis are extensions of the research performed by Trangsrud and Vaduri. Features of the model include suspension characteristics for (a) each of the five axles (tractor steer axle, two tractor drive axles, and two trailer axles), (b) tires, (c) a flexible engine mount, (d) the tractor cab, (e) the driver's seat, and (f) a fifth …
Design Of A Controller For A Precision Positioning Machine, Joshua Tarbutton
Design Of A Controller For A Precision Positioning Machine, Joshua Tarbutton
All Theses
System identification was used to build an accurate model of a high-precision measurement system. The model built by system identification was compared to modeling by first laws and showed extremely similar results. Pole-placement control design based on the identified system was used to place the systems' dominant poles. The necessary gains to achieve the desired system response were determined by using the identified model and knowledge of the controller structure. The performance of the model-based controller was compared to actual data of the system and showed that control based on the identified model can be used to accurately control the …
Energy Absorption Of Sine Wave Beams Subjected To Axial Impact Loading, Robert Smith
Energy Absorption Of Sine Wave Beams Subjected To Axial Impact Loading, Robert Smith
All Theses
Energy absorbers ideally remove kinetic energy efficiently and reliably while minimizing force magnitudes felt on the moving body. Until now, energy absorber design has concentrated on thin-walled prismatic tubes and tapered tubes. Sine wave beams (SWB) have been previously investigated as energy absorbers under lateral impacting situations only. This thesis investigates the energy absorption of the SWB under axial impact. FE models simulated the energy absorbing response of the SWB. Parametric analyses were performed using the structure's thickness, the web amplitude, and the period number of the web. The SWB's performance is evaluated and then compared to the prismatic structures. …
Machinability And Microstructure Stability During The Machining Of Pure Copper And Titanium Processed By Equal Channel Angular Pressing, Mason Morehead
Machinability And Microstructure Stability During The Machining Of Pure Copper And Titanium Processed By Equal Channel Angular Pressing, Mason Morehead
All Theses
For ultrafine grained materials (containing microstructures of 100-300 nm) to be manufactured and used in industry, machining research is needed to form and shape these materials into their final dimensions. Because of their high internal energy, UFG materials are known to have microstructures which are susceptible to undesirable changes at low temperatures. In this study, pure ultrafine grained copper and titanium as well as their respective coarse grained (CG) counterparts were tested for their relative machinability and microstructure stability through lathe turning. To evaluate the machinability cutting forces, tool wear, chip morphology, and surface roughness were studied using different cutting …
A Study Of Induced Drag And Spanwise Lift Distribution For Three-Dimensional Inviscid Flow Over A Wing, Scott Monsch
A Study Of Induced Drag And Spanwise Lift Distribution For Three-Dimensional Inviscid Flow Over A Wing, Scott Monsch
All Theses
Numerical results for an untwisted, finite rectangular wing (NACA 0012, AR = 6.7) using no flap deflections are compared against theoretical lifting line predictions. The numerical approach used an Euler-based computational fluid dynamic (CFD) solver. A span-wise lift distribution was extracted from the CFD solution. The comparison between the predicted numerical and lifting-line span-wise lift distributions shows good agreement with a maximum deviation of only 2.4% over the wing span.
The induced drag was extracted from the downstream wake using a wake integral technique referred to as Trefftz plane analysis. The predictions for induced drag based on surface integration, wake …
Dynamic Networking Of Exemplars: Towards A Mechanical Design Visual Programming Language, Shashidhar Putti
Dynamic Networking Of Exemplars: Towards A Mechanical Design Visual Programming Language, Shashidhar Putti
All Theses
Developing mechanical engineering design automation applications using current day textual programming languages like C, C++ requires extensive programming skills. However, learning to program in these environments can be time consuming and often frustrating to mechanical engineers due to the use of complex textual constructs and syntax to represent an algorithm in a linear fashion. Further, these programming languages offer a poor visualization of the data and the data flow due to their textual nature. The use of graphical objects for programming makes visualization easier and also eliminates the need for linear representation of algorithms. This thesis initiates the development of …
Emission Reduction In Small Displacement Diesel Engines Using Cooled Exhaust Gas Recirculation, Chris Simoson
Emission Reduction In Small Displacement Diesel Engines Using Cooled Exhaust Gas Recirculation, Chris Simoson
All Theses
A reduced-order dynamic model is presented and experimentally validated to demonstrate the use of cooled exhaust gas recirculation to alleviate the tradeoff between nitric oxide reduction and performance preservation in a small displacement diesel engine. Exhaust gas recirculation (EGR) is an effective method for internal combustion engine oxides of nitrogen (NOx) reduction, but its thermal throttling diminishes power efficiency. The capacity to cool exhaust gases prior to merging with intake air may achieve the desired pollutant effect while minimizing engine performance losses.
Simulation and experimental results revealed significant NOx reductions throughout all testing scenarios using EGR, but also experienced a …
Simulation And Characterization Of Tire Nonuniformity-Induced Steering Nibble Vibrations Through Integrated Subsystems Modeling, Derek Mangun
All Theses
Periodic force variations produced by nonuniform tire/wheel assemblies are known root causes of torsional steering wheel vibrations known as 'nibble'. Previous studies have sought to investigate this issue through modeling or experimentation involving the entire vehicle or specific subsystems, however a direct link between objectively measured tire force variations and the vibration levels perceived by vehicle occupants has yet to be established. Analytical models of a nonuniform tire, double-wishbone suspension system, and rack and pinion steering system are sourced from literature and integrated into a single subsystem-level model validated against experimental data obtained as part of a collaborative effort. The …
The Effects Of Viscoelastic Behavior On The Operation Of A Delayed Resonator Vibration Absorber, John Cowans
The Effects Of Viscoelastic Behavior On The Operation Of A Delayed Resonator Vibration Absorber, John Cowans
All Theses
Delayed resonators have proven to be effective vibration absorbers (VAs) for tracking and canceling the effects of harmonic excitations on a structure. The Delayed Resonator (DR) is selfcontained, as no information from outside of its substructure is required for proper operation. It adjusts for variations in frequency using time-delay and gain as control parameters.
This thesis examines the relationship between viscoelastic (VE) loss mechanisms in systems with DR and the choice of modeling method used to calculate control parameters and determine system stability. It is hypothesized that a VE loss mechanism approximated by a single viscous dashpot may lead to …
Internal Combustion Engine Cooling Strategies: Theory And Test, John Chastain
Internal Combustion Engine Cooling Strategies: Theory And Test, John Chastain
All Theses
Advanced internal combustion engine thermal management systems can enhance overall engine performance through the use of computer controlled cooling system actuators. Existing ground vehicle cooling systems generally have performance limitations due to the fixed behavior of the wax-based thermostat valve and crankshaft dependent operation of the coolant pump and radiator fan. Upgrading the traditional thermostat valve, water pump, and radiator fan with actuators permit real time computer control for improved temperature tracking and reduced power consumption. In this paper, the benefits associated with advanced automotive cooling systems are experimentally investigated. A 4.6L engine with a real-time data acquisition and control …