Mechanical Engineering Commons^™

Information Archival And Reuse: Drawing Conclusions From The Past, Matt R. Bohm

Doctoral Dissertations

"Over the last few decades design researchers have put forward theories and proposed methodologies that increase the chance that a design team will reliably arrive at the optimal solution to a given design problem. Studies, however, bear out that theories and methodologies alone will not guarantee an optimal or even good design solution. Instead, a breadth of knowledge across multiple engineering domains and the time and tools to thoroughly evaluate the design space are as important as any prescriptive design method. This work presents a set of underlying engineering technologies to define, archive and reuse product design knowledge to provide …

Investigation Of Selective Laser Sintering Of Zirconium Diboride Parts, Shashwatashish Pattnaik

Masters Theses

"This research investigates the fabrication of three-dimensional parts from ZrB₂, an ultra high temperature ceramic (UHTC), using the selective laser sintering (SLS) process. Based on an experimental investigation, optimum values for the SLS parameters (scan speed, laser power, energy density, scan spacing and layer thickness), used on a DTM Sinterstation 2000, were determined to build green ZrB₂ parts with high integrity and sharp geometrical features. This was done by melting the polymer binder used to bond the ceramic particles layer-by-layer according to the cross-section of a CAD model. The use of a sacrificial plate to eliminate cracks in the bottom …

Modeling Of Wear And Oxidation Behavior Of A Carbon/Carbon Multidisk Clutch, Shankar Nagaraj

Masters Theses

"Carbon/carbon composites are a family of advanced composite materials. They are the most advanced form of carbon and consist of a fiber, based on carbon precursors, embedded in a carbon matrix. They are extensively used in design of sliding contact systems such as clutches and brakes because of their low weight, excellent thermal and mechanical properties, chemical inertness and self lubricating capability. They retain their mechanical strength in inert atmospheres up to 2000° C. However, in oxidizing environments, C/C composites rapidly react with oxygen forming gaseous carbon oxides around 450° C.

In the present study a C/C composite clutch assembly …

Experiments And Modeling Of Shear-Driven Film Separation, J. L. Wegener

Masters Theses

"Dynamic thin liquid films driven by an adjacent gas flow have been subject to many investigations due to the presence of such films in many engineering applications. More specifically though, the behavior of such films at a sharply expanding corner has received little attention, but can be observed in internal combustion engines, liquid atomizer systems, refrigerant flows in evaporators, and film drag over wetted surfaces. Efforts to validate computational models of the propagation and separation of films are limited by the lack of reliable non-intrusive techniques to measure and analyze dynamic film parameters. In this study, film propagation models and …

Development Of An Electronic Governor System For A Small Spark Ignition Engine, Donald Ray Hibler

Masters Theses

"The use of electronic controls on engines has been widespread and has now reached the small utility engine. The evolution from carburetion to electronic fuel injection has presented opportunity to implement additional controls with the intent to improve engine control and performance. In this study, an electronic governor system is developed for use on a small twin cylinder utility engine. This system is to replace an existing mechanical governor system, and it should have the potential as a production based solution that integrates with an existing fuel injection system. It must improve the speed droop characteristics over the current mechanical …

Modeling And Simulation Of High Pressure Composite Cylinders For Hydrogen Storage, Jianbing Hu

Doctoral Dissertations

"Composite hydrogen cylinders provide an efficient means of storage of hydrogen gas for modern hydrogen vehicles. Safety issues arising from the high gas pressure, temperature variation, fire attack, and fracture failures are the main concerns. The focus of this study is to develop a Finite Element (FE) model to predict the performance of composite cylinders subjected to extreme mechanical/thermal loadings and provide guidance for design optimization"--Abstract, page iv.

Fundamentals Of Friction Stir Spot Welding, Harsha Badarinarayan

Doctoral Dissertations

"The recent spike in energy costs has been a major contributor to propel the use of light weight alloys in the transportation industry. In particular, the automotive industry sees benefit in using light weight alloys to increase fuel efficiency and enhance performance. In this context, light weight design by replacing steel with Al and/or Mg alloys have been considered as promising initiatives. The joining of structures made of light weight alloys is therefore very important and calls for more attention. Friction Stir Spot Welding (FSSW) is an evolving technique that offers several advantages over conventional joining processes.

The fundamentals aspects …

Systematic Functional And Object-Oriented Product Design Frameworks, Jen-Chi Wu

Doctoral Dissertations

"The existing co-design methods of mechatronic products focus on co-design of mechanical and electronic components or co-design of computer hardware and software components. There exist no effective co-design methods for mechanical, electronic and software components at the concept design stage. The research objective of this dissertation work is to develop more effective systematic product design approaches for co-design of mechatronic products. Three innovative functional and object-oriented integrated design frameworks and one virtual prototyping application, which leverages on these three design frameworks, have been developed for co-design of mechatronic products. The three frameworks are: I) Hierarchical Object-Oriented Functional Modeling Framework, 2) …

Verifying Module Heuristics For Large Scale Products, Rachel Marie Day

Masters Theses

"Decreasing time and costs is a major objective in many businesses today. Including modularity in the early design phases can effectively decrease time spent on and costs associated with a project. The task of identifying modules within a product early in the design process (when decisions are less expensive) is made less daunting by using the techniques of functional modeling and module heuristics. The two papers that form this thesis discuss the results of the efforts to verify the module heuristics on large products. Observations on needed modifications to the functional modeling technique and original module heuristics are reported along …

Modeling And Simulation Of Electrochemical Magneto Hydro Dynamics, Debamoy Sen

Masters Theses

"This thesis focuses on how the electrochemical magneto hydro dynamic problem is solved through numerical simulation for a two dimensional millielectrode electrochemical cell and a three dimensional microelectrode array cell. Electrochemical processes are enhanced by magnetic fields through the introduction of body forces such as Lorentz force. Through modeling and numerical simulations, experimental results can be integrated with theory. Such simulations will aid in the prediction of mass transfer limited currents and visualization of flow profiles in an electrochemical cell. The numerical solution of the equation system is made possible by the finite volume method used in the FLUENT Computational …

Decision-Based Design Under Uncertainty With Intervals, Sashank Vasireddy

Masters Theses

"Design requires a series of decisions, and one of the major challenges engineering designers face is making decisions under uncertainty. The engineering designer must choose the best design among various alternatives. This work evaluates the use of utility functions to make decisions under uncertainty with both random and interval variables. Uncertainty cannot be eliminated completely, but it can be reduced. Most current methods treat only aleatory uncertainty. Here, however, both aleatory and epistemic uncertainties are addressed in the context of engineering design. Methods such as moment matching method and worst case analysis are used to incorporate uncertainty into design problems"--Abstract, …

Reliability-Based Design With System Reliability And Design Improvement, Gagandeep Singh Saini

Masters Theses

"This thesis focuses on developing a methodology for accurately estimating series system probability of failure. Existing methods for series system based design optimization are not that accurate because they assign reliability to each failure mode; as a result complete system reliability goes down. According to method proposed in this work, the user will assign required system reliability at the start and then optimizer will apportion reliability to every failure mode in order to meet required system reliability level. Detlevson second order upper bounds are used to estimate system probability of failure. Several examples have been shown to verify the results …

Development Of Extrusion On Demand For Ceramic Freeze-Form Extrusion Fabrication Processes, Parimal Sanjay Kulkarni

Masters Theses

"Freeze-form Extrusion Fabrication (FEF) is a Solid Freeform Fabrication method. It involves the deposition of a ceramic paste in a layer by layer manner to construct a three dimensional structure. The ceramic paste used in this process consists of a high solids loading of ceramic powder mixed with water and a nominal amount of an aqueous organic binder. These characteristics make the process environmentally friendly. Also the absence of dies or molds in the process makes it suitable for fabrication of materials like ceramics. In the past, parts have been fabricated with continuous extrusion of a ceramic paste. In FEF, …

Hydrogen Applications For Lambert - St. Louis International Airport, Mathew Thomas

Masters Theses

"Today, major airports are facing challenges related to pollution, energy efficiency, and safety and security. Hydrogen and fuel cell technologies, regarded as one of the key energy solutions of the 21st century are more energy efficient and reliable than conventional systems and have the potential to diminish these challenges. These technologies can also play a significant role in reducing the noise, air, and water pollution and enhancing energy security. This paper presents the design of a set of hydrogen technologies and systems that are commercially available and are ready for practical, real-world use. The hydrogen applications selected for Lambert-St. Louis …

Filtering, Modeling, And Control Of Axial Force Signals In Friction Stir Welding Processes, Thomas Michael Oakes

Masters Theses

"In Friction Stir Welding Processes, good contact between tool and work piece can be accomplished through control of the axial force signals. A method of stochastic modeling is introduced and used in conjunction with a Kalman filter to develop empirical static and dynamic models relating the axial force to input process parameters. The filtering method reduces signal variance by an order of magnitude. The models are experimentally validated and used to design and implement a general tracking controller with disturbance rejection for axial force control. Online control of the axial force is experimentally validated for bead-on-plate welds using a 6061 …

On-Line Depth Measurement Of Micro-Scale Laser Drilled Holes, Rock Allen Powell

Masters Theses

"A micron-precision micro-hole depth detection scheme has been developed which utilizes a confocal structure and a photomultiplier tube as a photodetector. This scheme is experimentally confirmed to posses an accuracy of greater than 95% for micro-holes on the order of one-hundred microns in diameter and tens of microns in depth and could be easily be integrated for the control of industrial and research oriented laser micro-machining process"--Abstract, page iii.