Engineering Commons^™

Manufacturing And Characterization Of Soy-Based Pultruded Polyurethane Composites, Rama Bhadra Raju Vuppalapati

Masters Theses

"In the recent past, composites have been finding various applications in civil infrastructure, marine, transportation, automotive and non-automotive applications by replacing metals in structural components. Pultrusion is considered to be a cost effective method for manufacturing composite materials.

Polyurethane resin systems form a good alternative to the conventional styrene based systems in pultrusion due to their better physical, chemical and mechanical properties. Polyols derived from soybean oil along with isocyanates produce polyurethanes that can match in many aspects with one derived from the petrochemical polyols. Even though, polyurethanes have good properties there are lots of challenges like designing unique material …

On-Line Inspection And Thermal Properties Comparison For Laser Deposition Process, Yu Yang

Masters Theses

"This thesis is focused on comparing the laser deposition cladding with intended design model and comparing the effect of laser deposition process on thermal properties with traditional welding process. It is research on two aspects of laser deposition cladding. The first part of the thesis is aimed at solving the geometric inspection of laser deposition cladding, and the second part is for comparing the thermal properties of laser deposition cladding to samples of conventional welding process"--Introduction, page 1.

Development Of A Liquid Injection Propane System For Spark-Ignited Engines Via Fuel Temperature Control, Brian Charles Applegate

Masters Theses

"This work describes the development of a thermally controlled liquid propane injection system...A liquid fuel system, as described in this work, offers power gains over vaporized fuel introduction due to the ability to use the heat of vaporization from the vaporizing fuel to cool the intake charge and improve the volumetric efficiency of the engine. This system uses temperature to control the state of the fuel in the fuel system"--Introduction, page 1.

Transient Performance Of Closed Loop Thermosyphons Incorporating Thermal Storage, Kyle S. Benne

Masters Theses

This thesis considers a unique application of a thermosyphon to a conventional thermal storage deice. In such an application, the dynamics of the thermosyphon are coupled with the condition of the storage volume. This thesis specifically focuses on the transient energy addition or charge process, where heat accumulated within the storage volume continuously decreases the driving buoyant force and volumetric flow rate"--Abstract, page iv.

Optimal Formation Of Supplier Networks For Product Design And Production Phases To Realize An Evolving Product Family, Padmavathi K. Pakala

Masters Theses

"Due to rapid changes in customer requirements and vast improvements in technology, many product development companies have identified strategies like time-to-market (TTM) compression and product family development as critical for attaining success in today's hyper-competitive markets. Compressing the TTM, to a large extent, is dependent on the suppliers and the project execution skills of the integrator companies. This study presents a methodology for selecting suppliers for two significant phases of the product realization process, namely, product design and production. The proposed methodology uses a two-stage approach for supplier selection where suppliers for product design are selected in the first stage …

Development, Modeling, And Simulation Of A Nano Aerial Vehicle Using Empirical Data, Wyatt Emery Davenport

Masters Theses

"The ultimate goals of this study were to use experimental data to estimate the flight capabilities of a flapping wing nano aerial vehicle (NAV), estimate the power required to provide such flight, and develop a controller approach for future use in the design of this aircraft. The experimental data is a collection of measurements of the normal force on a flapping wing taken in stationary water, and was used to develop empirical coefficient derivatives for use in the dynamic modeling of the NAV"--Abstract, page iii.

E-Design Tools For Friction Stir Welding: Cost Estimation Tool, Pradeep Kumar Tipaji

Masters Theses

"A cost model is an important tool for product design and material selection. An efficient and effective cost estimation tool is necessary for early design evaluation. In this paper, cost estimation models that estimate the production cost for Metal Inert Gas (MIG), Friction Stir (FS), and Friction Stir Spot (FSS) welded joints are presented. These models determine the cost incurred to fabricate each joint along with a detailed explanation of each cost component. Each cost component has been closely analyzed and major cost components have been included in the cost model"--Abstract, page iv.

Empirical Dynamic Modeling And Nonlinear Force Control Of Friction Stir Welding, Xin Zhao

Masters Theses

"Current Friction Stir Welding (FSW) process models are mainly concerned with the detailed analysis of material flow, heat generation, etc. and therefore, are computationally intensive. Dynamic models describing the total forces acting on the tool throughout the entire welding process are required for the design of feedback control strategies and improved process planning and analysis. In this thesis, empirical models relating the process parameters (i.e., plunge depth, travel speed, and rotation speed) to the process variables (i.e., axial, path, and normal forces) are developed to describe their dynamic relationships"--Abstract, page iv.

Selective Laser Sintering Of Stearic Acid-Coated Alumina Ceramic, Jason J. Nolte

Masters Theses

"The purpose of this research is to develop a process that will enable a Selective Laser Sintering (SLS) machine to create geometrically complex green parts of various sizes that become strong, dense ceramic parts after sintering. This will be applicable to SLS systems already operational in industry, and may offer a more cost-effective, more time-efficient method for producing high-temperature ceramic rapid prototype parts. Alumina was the chosen ceramic for the developmental stage of this research. Fine alumina powder (average particle size of 0.4 µm) was coated with stearic acid, which served as a binder. Green parts were made from this …

Compressor Valve Failure Detection And Prognostics, Raghuram Puthali Ramesh

Masters Theses

"Reciprocating compressors are commonly used machinery for industrial applications. Unscheduled downtime and maintenance activity on the compressors causes considerable loss in throughput and efficiency of a plant. Of all the failures that cause unscheduled downtime in reciprocating compressors, valve related causes are predominant. Most of the failures associated with the valves are tracked to the failure of moving elements within the valve. Achieving higher reliability of critical reciprocating systems requires continuously monitoring the system and performing dynamic analysis of the sensory data for valve fault diagnosis. Continuous monitoring will improve the time and cost to repair through keeping a constant …

Adhesion-Delamination Mechanics Of Linear And Axisymmetric Film At Film-Substrate Interface, Ming-Fung Wong

Masters Theses

"This thesis is to characterize the thin membrane adhesion-delamination phenomena which occur in biological cells and micro-electro-mechanical systems (MEMS) operation. The delamination of a thin film adhered to a rigid substrate is subjected to the coupling effects of tensile residual stress and interfacial adhesion energy. The adhesion-delamination mechanics is derived using the classical linear elasticity and thermodynamics energy balance. The membrane deformation is here dominated by a mixed plate-bending and membrane-stretching, while the concomitant stress is neglected. An 1-dimensional model is first investigated where a pre-stressed rectangular film clamped at both ends delaminates from a rigid punch of the same …

Manufacturing Of High Performance Composites Using Vacuum Assisted Resin Transfer Molding, V. G. K. Menta

Masters Theses

"The objective of this research is to establish and enhance the existing Vacuum Assisted Resin Transfer Molding (VARTM) process to manufacture high performance composite parts usable in the aerospace industry.

Flat, hat, pi and multi stiffened panels have been manufactured by the VARTM process using AS4-5HS and AS4-8HS carbon fabric, and SI-ZG-5A low viscosity epoxy resin. Silicone-based reusable molds have been designed and developed to manufacture stiffened panels. Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) experiments of the SI-ZG-5A resin system were conducted to determine the storage modulus, loss modulus, and the glass transition temperature. The density and …

Towards A Methodology For Integrated Freeform Manufacturing Systems Development With A Control Systems Emphasis, Jacquelyn K. Stroble

Masters Theses

"A variety of fully integrated Freeform Fabrication (FFF) systems have been developed, a selected group for research and several for commercialization. The design methodology behind most of them is not documented, standardized, or rational. It is important to understand that the final product from any integrated system is affected not only by the unit manufacturing processes themselves, but also by the extent the individual units are assimilated into an integrated process. Thus, a scheme consisting of eight steps and the salient five elements necessary to create or retrofit an existing system to achieve an Integrated Freeform Manufacturing System (FFMS) is …

Mechanical Properties And Microstructure Study For Direct Metal Deposition Of Titanium Alloy And Tool Steel, Yaxin Bao

Masters Theses

"This thesis is focused on the research about DMD (Direct Metal Deposition) which is an additive manufacturing process and used in various engineering applications such as producing fully dense and net shape productions in difficult-to-machine materials. In this study, the microstructure was analyzed through optical microscopy and some mechanical properties were tested with different equipments such as SEM (Scanning Electron Microscopy) and micro-hardness tester...In summary, this thesis validated that DMD process can be improved through surface treatments and is capable of repairing molds for die casting industry"--Introduction, page 1.

Empirical Investigation Of Enhanced Air Fins, Stephen John Dale Rucker

Masters Theses

"Enhanced convective heat transfer surfaces have been a subject of interest for quite some time. Many different methods have been used to increase the amount of heat transfered from a surface. However, nearly all surface enhancement methods come with a price, frictional losses. This thesis studies the use of enhanced convective heat transfer surfaces on air fins in the laminar, transitional, and turbulent flow regimes with emphasis on the transitional regime. A major goal of this thesis is to further the understanding of the influence of an enhanced wall geometry on the transition from laminar to turbulent flow. Causing the …

Modeling And Control Of Freeze-Form Extrusion Fabrication, Xiyue Zhao

Masters Theses

"Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technique that extrudes ceramic loaded aqueous pastes layer by layer below the paste freezing temperature for component fabrication. As the FEF is aimed at being conducted at low environmental temperatures, down to -20°C, it is necessary to investigate the effect of environmental temperature on the process. The advantages of fabrication at low temperature have been proved by experiments. Comparisons in terms of operation parameters, self-sustaining ability, and system dynamic response were performed at different environmental temperatures ranging from 20°C to -20°C.

It is commonly known in paste extrusion processes that due to …

Robust Mechanism Synthesis With Random And Interval Variables, Pavan Kumar Venigella

Masters Theses

"Robust mechanism synthesis ensures that the performance of a mechanism is not sensitive to uncertainties in the mechanism and its environment. The uncertainties include the dimension variations, installation errors, random input motion, and various external forces. Robust mechanism synthesis is used to minimize the impact of these uncertainties on the mechanism performance. Robust mechanism synthesis has been performed by either a probabilistic approach or a worst case approach. The former approach describes uncertain parameters as random variables while the latter approach treats uncertain parameters as interval variables. In this work, methods are developed for robustness assessment and robust mechanism synthesis …