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Articles 91 - 120 of 180

Full-Text Articles in Engineering Science and Materials

Survey Of Concurrent Engineering Environments And The Application Of Best Practices Towards The Development Of A Multiple Industry, Multiple Domain Environment, Jonathan Osborn Aug 2009

Survey Of Concurrent Engineering Environments And The Application Of Best Practices Towards The Development Of A Multiple Industry, Multiple Domain Environment, Jonathan Osborn

All Theses

This thesis investigates the best practices of fifteen existing Concurrent Engineering Environments (CEE). A CEE is defined as any environment, from physical to virtual, designed to facilitate concurrent engineering with multiple domain experts real time. All existing environments surveyed have been focused on the aerospace industry showing significant reductions in design time and cost. I have identified hardware, software, and peopleware as three major classifications as well as sixteen subcategories with which to compare the different CEEs. The success in reducing time and cost of designs seen in the aerospace industry with the introduction of CEEs can and should be …

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Dynamic Finite Element Simulation Of Ultrasonic Consolidation, Daniel Mccullough Aug 2009

Dynamic Finite Element Simulation Of Ultrasonic Consolidation, Daniel Mccullough

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Ultrasonic Consolidation (UC) is a promising solid state rapid manufacturing process that provides the ability to create functional, multilayered, and often geometrically complex parts. This thesis seeks to address one of the primary obstacles faced when using the process, namely the apparent build height limit encountered when using UC to construct high aspect ratio specimens. A fully transient, three dimensional Finite Element model is created to study the dynamic behavior of an ultrasonically consolidated part during the UC process. The model is used to find the cause of bond failure at the build height limit and a potential way to …

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Predictive Energy Management In Smart Vehicles: Exploiting Traffic And Traffic Signal Preview For Fuel Saving, Behrang Asadi Aug 2009

Predictive Energy Management In Smart Vehicles: Exploiting Traffic And Traffic Signal Preview For Fuel Saving, Behrang Asadi

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This master thesis proposes methods for improving fuel economy and emissions of vehicles via use of future information of state of traffic lights, traffic flow, and deterministic traffic flow models.
The first part of this thesis proposes use of upcoming traffic signal information
within the vehicle's adaptive cruise control system to reduce idle time at stop lights and lower fuel use. To achieve this goal an optimization-based control algorithm is formulated for each equipped vehicle that uses short range radar and traffic signal information predictively to schedule an optimum velocity trajectory for the vehicle. The objectives are timely arrival at …

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Development And Integration Of Geometric And Optimization Algorithms For Packing And Layout Design, Santosh Tiwari Aug 2009

Development And Integration Of Geometric And Optimization Algorithms For Packing And Layout Design, Santosh Tiwari

All Dissertations

The research work presented in this dissertation focuses on the development and application of optimization and geometric algorithms to packing and layout optimization problems. As part of this research work, a compact packing algorithm, a physically-based shape morphing algorithm, and a general purpose constrained multi-objective optimization algorithm are proposed. The compact packing algorithm is designed to pack three-dimensional free-form objects with full rotational freedom inside an arbitrary enclosure such that the packing efficiency is maximized. The proposed compact packing algorithm can handle objects with holes or cavities and its performance does not degrade significantly with the increase in the complexity …

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A Study In The Information Content, Consistency, And Expressive Power Of Function Structures In Mechanical Design, Chiradeep Sen May 2009

A Study In The Information Content, Consistency, And Expressive Power Of Function Structures In Mechanical Design, Chiradeep Sen

All Theses

In engineering design research, function structures are used to represent the intended functionality of technical artifacts. Function structures are graph-based representations where the nodes are functions, or actions, and the edges are flows, or objects of those actions. For the consistent description of artifact functionality, multiple controlled vocabularies have been developed in previous research. The Functional Basis is one such vocabulary that provides for a set of verbs and a set of nouns, organized in the three-level hierarchy. This vocabulary is extensively studied in design research. Two major application of this vocabulary are the Design Repository, which is a web-base …

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A Priori Analysis Of Subgrid Scalar Phenomena And Mass Diffusion Vectors In Turbulent Hydrogen-Oxygen Flames, Justin Foster May 2009

A Priori Analysis Of Subgrid Scalar Phenomena And Mass Diffusion Vectors In Turbulent Hydrogen-Oxygen Flames, Justin Foster

All Theses

Direct Numerical Simulations (DNS) of high pressure, turbulent H2/O2 non-premixed flames employing real gas effects, detailed chemistry, multicomponent, differential, and cross diffusion are conducted. The results of these simulations are analyzed to provide important subgrid information relevant to Large Eddy Simulation (LES) of turbulent combustion. Subgrid filtered scalar dissipation and scalar variances, species concentrations, reaction rates, and flame temperature are presented as a function of mixture fraction. The analysis also includes a detailed comparison of the actual filtered mass flux vectors with their corresponding forms evaluated with the filtered primitive variables. The results show a reasonable correlation …

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Development Of A Nonlinear Ride Quality Model To Aid In Tweelå© Parameter Selection, Marc Paradiso May 2009

Development Of A Nonlinear Ride Quality Model To Aid In Tweelå© Parameter Selection, Marc Paradiso

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The ride comfort of a vehicle is very important to both automotive and tire manufacturers. Unfortunately the ride comfort provided by the tire has an inverse relationship with the handling ability of the vehicle. Michelin has sought to decouple ride comfort and handling capability by developing a non-pneumatic tire they have dubbed the TWEEL©. To better understand what effects fitting a TWEEL with specific characteristics would have on the ride comfort of a vehicle a computer simulation was developed to study the effects of TWEEL stiffness and deflection on ride comfort.
The vehicle model used in the simulation is a …

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Development Of A Falling Sphere Instrument For High-Resolution Neutral Wind Measurements In The Mesosphere And Lower Thermosphere, Arpan Shah May 2009

Development Of A Falling Sphere Instrument For High-Resolution Neutral Wind Measurements In The Mesosphere And Lower Thermosphere, Arpan Shah

All Theses

Passive falling spheres launched from small rockets have been used extensively in the past to measure the winds and densities in the mesosphere. In principle, the same technique can be extended to higher altitudes that cover the lower thermosphere, in addition to the mesosphere. The main difficulties are that accelerations decrease rapidly with height due to the decreasing atmospheric density and rigid spheres are required at higher altitudes, which implies larger mass and smaller accelerations. Accelerometers with broad dynamic range and high sensitivity are required for the measurements, but such devices are not readily available. We describe an instrumented falling …

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An Evaluation Of Function-Based Representations And Information Archival In Engineering Design, Benjamin Caldwell May 2009

An Evaluation Of Function-Based Representations And Information Archival In Engineering Design, Benjamin Caldwell

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Recent research in function-based design includes the development of a vocabulary of functions, the Functional Basis, and a repository of products and their functions. Many design tools are being developed around this vocabulary and repository to support conceptual design. The usefulness of these tools, however, is dependent on the quality of the vocabulary and the information contained in the repository. In this research, both the vocabulary and the repository are empirically evaluated to understand their strengths and limitations. A statistical analysis is performed on function models in the repository to determine the frequency of usage of Functional Basis terms. It …

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Taxonomy Of Physical Prototypes: Structure And Validation, Ashwin Michaelraj May 2009

Taxonomy Of Physical Prototypes: Structure And Validation, Ashwin Michaelraj

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This thesis introduces a taxonomy of physical prototypes, and validates the proposed taxonomy by five different approaches. The proposed taxonomy is validated by, (i) checking the orthogonality of individual elements of the taxonomy, (ii) benchmarking the taxonomy with existing classifications of prototypes, (iii) demonstrating its utility by applying it to classify different prototypes, (iv) building a prototype database containing 35 different prototypes, and (v) consistency evaluation of the prototype database using a description logic based software called ProtŽgŽ.
The results indicate that the proposed taxonomy is capable of distinguishing prototypes with greater accuracy when compared to existing classifications. The orthogonality …

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Development, Parameterization And Validation Of Dynamic Material Models For Soil And Transparent Armor Glass, Bhaskar Pandurangan May 2009

Development, Parameterization And Validation Of Dynamic Material Models For Soil And Transparent Armor Glass, Bhaskar Pandurangan

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Despite the signing of several mine ban treaties in the 1990's, it is widely recognized that there is a landmine crisis. The following are some of the main aspects of this crisis: (a) Millions of unexploded landmines remain deployed all over the world; (b) Thousands of civilians are killed or maimed every year by unintended detonations of the mines; (c) The cost of medical treatment of landmine injuries runs into the millions; (d) the ability of the international community to provide the humanitarian relief in terms of medical services, safe drinking water and food, etc., is greatly hampered by landmine …

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Foundations Of Design Method Development, Sudhakar Teegavarapu May 2009

Foundations Of Design Method Development, Sudhakar Teegavarapu

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A systematic procedure for developing design methods, tools, and/or processes, referred to as meta-method, is proposed. It is hypothesized that design methods developed without following a systematic procedure are not effective and thus are not widely accepted by industry and academia likewise. The systematic framework provided by the meta-method will ensure 1) faster development of design methods, 2) enable tracking of requirements throughout the development process, 3) facilitate efficient exploration and selection of alternatives, 4) document the development process for future reuse, 5) help in testing and validation of design methods, and 6) bridge gap between multiple disciplines by forming …

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Microcantilever-Based Force Sensing, Control And Imaging, Reza Saeidpourazar May 2009

Microcantilever-Based Force Sensing, Control And Imaging, Reza Saeidpourazar

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This dissertation presents a distributed-parameters base modeling framework for microcantilever (MC)-based force sensing and control with applications to nanomanipulation and imaging. Due to the widespread applications of MCs in nanoscale force sensing or atomic force microscopy with nano-Newton to pico-Newton force measurement requirements, precise modeling of the involved MCs is essential. Along this line, a distributed-parameters modeling framework is proposed which is followed by a modified robust controller with perturbation estimation to target the problem of delay in nanoscale imaging and manipulation. It is shown that the proposed nonlinear model-based controller can stabilize such nanomanipulation process in a very short …

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Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal Dec 2008

Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal

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Vehicle Dynamics Control (VDC) systems, also called Electronic Stability Control (ESC) systems, are active on-board safety systems intended to stabilize the dynamics of vehicle lateral motion. In so doing, these systems reduce the possibility of the driver's loss of control of the vehicle in some critical or aggressive maneuvers. One approach to vehicle dynamics control is the use of appropriate drive torque distribution to the wheels of the vehicle. This thesis focuses on particular torque distribution management systems suitable for vehicles with independently driven wheels.
In conducting this study, a non-linear seven degree-of-freedom vehicle model incorporating a non-linear tire model …

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Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora Dec 2008

Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora

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A distributed parameters modeling and control framework for flexible solid-state hysteretic actuator is presented in this work. For the simplicity of analysis, the actuator dynamic behavior is decoupled and treated separately from the hysteresis nonlinearity. To include the effects of widely-used flexural mechanisms, a mass-spring-damper boundary condition is considered for system. Moreover, the effect of electromechanical actuation is included as a concentrate force at the boundary. The problem is then divided into two parts: first part deals with free motion analysis of system in order to obtain eigenvalues and eigenfunctions using the expansion theorem and a standard eigenvalue problem procedure. …

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An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan Dec 2008

An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan

All Theses

In order to design car body structures which are safe during crash, modern automotive manufacturers perform both full-scale experimental crash tests and computer simulation of vehicle crash events using commercially available Finite Element Analysis (FEA) packages such as ABAQUS or LS-DYNA. Use of crash simulations significantly reduces the number of real time crash experiments needed and reduces the time required for design changes. However, in order to capture accurately crash behavior during high-speed impact, a large amount of detailed FEA modeling features such as number and types of elements, mesh element size, number of components, different types of connectors, material …

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Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling Dec 2008

Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling

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Advances in micromachining technology have enabled the design and development of high performance microelectromechanical systems (MEMS). There is a pressing need for control techniques that can be used to improve the dynamic behavior of MEMS such as the response speed and precision. In MEMS applications, open-loop control is attractive as it computes a priori the required system input to achieve desired dynamic behavior without using feedback, thus eliminating the problems associated with closed-loop MEMS control. While the input-shaping control is attractive due to its simplicity, the effectiveness of this control approach depends on the accuracy of the model that is …

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Nonlinear Finite Element Analysis Of Tweel Geometric Parameter Modifications On Spoke Dynamics During High Speed Rolling, Maya Ramachandran Dec 2008

Nonlinear Finite Element Analysis Of Tweel Geometric Parameter Modifications On Spoke Dynamics During High Speed Rolling, Maya Ramachandran

All Theses

The acoustic signature and noise produced by non-pnuematic wheels such as the Michelin TWEELTM is a critical design criteria for automotive and other mobility applications. The TWEELTM structure consists of three basic parts: (1) a circular deformable 'shear beam', (2) collapsible spokes and (3) a rigid hub. During high speed rolling the TWEELTM produces acoustic noise which is hypothesized to be due to resonant vibration of the TWEELTM spokes as they enter the contact region, buckle and then snap back into a state of tension. In order to identify and help understand the causes of acoustic noise for a rolling …

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Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson Dec 2008

Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson

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An energy dissipation system is proposed for use on consumer passenger automotive vehicles and auto racing stock cars. This system will be utilized to protect the occupants from frontal impacts with stationary or near stationary objects. The system will be affixed to the front of the car's primary structure. It is proposed to replace the traditional steel bumper currently in use. This system will not increase the weight of the car, nor will it adversely affect the aerodynamics of the body. The system will improve the crashworthiness of the vehicle. Advanced composites will be the primary sacrificial element in the …

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Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash Dec 2008

Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash

All Dissertations

Piezoelectrically-driven (piezoactive) systems such as nanopositioning platforms, scanning probe microscopes, and nanomechanical cantilever probes are advantageous devices enabling molecular-level imaging, manipulation, and characterization in disciplines ranging from materials science to physics and biology. Such emerging applications require precise modeling, control and manipulation of objects, components and subsystems ranging in sizes from few nanometers to micrometers. This dissertation presents a comprehensive modeling and control framework for piezoactive micro and nano systems utilized in various applications.
The development of a precise memory-based hysteresis model for feedforward tracking as well as a Lyapunov-based robust-adaptive controller for feedback tracking control of nanopositioning stages are …

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Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam Dec 2008

Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam

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In this dissertation, research in two parallel directions is presented; the first involves the prediction of the final size and shape of a glass lens during a precision glass lens molding process and the second introduces a method to compute and quantify the importance of higher order terms in fracture mechanics for different modes of fracture.
The process of precision lens molding has received attention in recent years due to its potential to mass produce aspherical lenses. Aspherical lenses have significantly better optical properties and conventional lens making techniques are limited to manufacturing of spherical lenses only. The conventional technique …

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Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg Sep 2008

Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg

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This thesis investigates possible fuel economy gains attainable by a combination of high-power density ultracapacitors (also called supercapacitors) and an induction motor integrated into a conventional vehicle powertrain for power assistance.
Periods of quick acceleration require a much higher power output from an automobile than what is encountered under more typical driving conditions. A simple kinetic energy calculation can show that accelerating a 2000 kg vehicle (roughly the size of a Ford Explorer SUV) from 0 to 60 mph in 10 seconds requires almost 70 kW of power, in addition to the power needed to overcome road and air drag …

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Non-Linear Finite Element Analysis And Optimization For Light Weight Design Of An Automotive Seat Backrest, Prasanna Balaji Thiyagarajan Aug 2008

Non-Linear Finite Element Analysis And Optimization For Light Weight Design Of An Automotive Seat Backrest, Prasanna Balaji Thiyagarajan

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ABSTRACT
With the goal of reduced weight, free-size finite element based optimization with constraints on stresses and displacements of a commercially available automotive seat backrest frame manufactured from several stamped and welded low carbon ductile steel sheets is performed using OptiStruct linear optimization package from Altair under the loading requirements of mandatory ECE R-17 backrest-moment test and headrest test for vehicles sold in Europe. In the free-size optimization, sheet metal thickness in a finite element shell model of the backrest frame are design variables with stress and displacement limits as the constraints, with an objective to minimize mass. Using the …

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Similarity Metrics Applied To Graph Based Design Model Authoring, Srinivasan Anandan Aug 2008

Similarity Metrics Applied To Graph Based Design Model Authoring, Srinivasan Anandan

All Dissertations

Model reuse is typically facilitated by search and retrieval tools, matching the sought model with models in a database. This research aims at providing similar assistance to users authoring design exemplars, a data structure to represent parametric and geometric design problems. The design exemplar represents design problems in the form of a bi-partite graph consisting of entities and relations. Authoring design exemplars for relatively complex design problems can be time consuming and error prone. This forms the motivation of developing a search and retrieval tool, capable of retrieving exemplars that are similar to the exemplar that a user is trying …

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A Comprehensive Multiphysics, Multiscale Modeling Framework For Carbon Nanotube Fabrication Process By Chemical Vapor Deposition, Mahmoud Reza Hosseini Aug 2008

A Comprehensive Multiphysics, Multiscale Modeling Framework For Carbon Nanotube Fabrication Process By Chemical Vapor Deposition, Mahmoud Reza Hosseini

All Dissertations

Carbon nanotubes (CNTs) are among the most promising nanosize materials as evidenced by the attention they have received since their discovery in 1991 and a wide range of scientific and industrial applications. Each of these applications requires unique CNTs with specific length, diameter and chirality. However, control of these parameters is considered as one of the main challenges for large scale production of CNTs. Furthermore, these processes are not well designed so as to limit the number of CNT defect sites or the production of unwanted byproducts such as amorphous carbon. Therefore, it is crucial to develop a controlled CNTs …

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Analysis Of Non Load Bearing Two Component (2k) Adhesives; Under The Automotive Hemming Process Variations; Thermogravimetric, Calorimetric And Composition Analyses, Kameswara Nara Jul 2008

Analysis Of Non Load Bearing Two Component (2k) Adhesives; Under The Automotive Hemming Process Variations; Thermogravimetric, Calorimetric And Composition Analyses, Kameswara Nara

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The work focuses on the analysis of non-load bearing, two component adhesives used in joining the automotive closures. The study is concerned with the thermo-gravimetric and the calorimetric attributes of the 2K adhesive. The study includes the impact of the robotic applicators capability, in terms of the mixing ratio between the resin and the hardener, and the mechanical mixing quality. A Fourier Transform Infrared Spectroscopy (FTIR) procedure analyzes the adhesive chemical groups and tracks the growth and decay of the hydroxyl and epoxy peaks. Additionally, the cure-rate based on a reaction-type, is investigated through a Differential Scanning Calorimetry (DSC). The …

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Quantitative Modeling Of Soil Properties Based On Composition And Application To Dynamic Tire Testing, Sumalatha Yaski Jul 2008

Quantitative Modeling Of Soil Properties Based On Composition And Application To Dynamic Tire Testing, Sumalatha Yaski

All Theses

A new dimension of success in automotive supply is time-based competition. This especially comes to light in tire development, with companies striving to enhance the testing methodologies for reduction in development time. Modeling and development of off-road tires is particularly difficult due to a lack of quantitative descriptions of the operating environment for model validation. Off-road tire evaluation is subjective, expensive, site dependent, and testing of such tires is typically carried out under lower levels of control. The objective of this work is to create fundamental descriptions of pertinent composition based soil properties and to directly relate these properties to …

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Three Design Tool Focused Case Studies Of Mechanical Engineering Design Projects, William Miller Jul 2008

Three Design Tool Focused Case Studies Of Mechanical Engineering Design Projects, William Miller

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Three long term mechanical engineering design projects spanning 24 months, 12 months, and 4 months are examined in this thesis. These projects are used to explore the development of a way to represent information flow throughout the design process with respect to design tools used. This is a first step in a broader effort to formalize 1) modeling of design processes, 2) establishing case study research as a formal approach to design research, and 3) developing new design process tools.
A survey of existing models compares the differences between current approaches and the limitations of each. Inspired by IDEF0, an …

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Enhancement Of Information Management Capabilities In Mdo Framework, Santosh Hiriyannaiah Jul 2008

Enhancement Of Information Management Capabilities In Mdo Framework, Santosh Hiriyannaiah

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Multidisciplinary Design Optimization (MDO) frameworks have been developed to facilitate the integration of disciplinary analysis codes and optimization techniques. Recent advances in MDO frameworks have addressed issues related to data exchange, distributed computing, process integration and trade study. However, managing, storing and sharing MDO problem information have not yet been fully addressed. In this research a software configuration is proposed. The configuration is built upon a structured repository, common file system and software applications. The configuration is integrated into a commercially available MDO framework to manage, store and share MDO problem information. A common file system proposed in this research …

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Reduction Of Sink Marks In Wire Insert Molded Parts, Gauri Phadke Jul 2008

Reduction Of Sink Marks In Wire Insert Molded Parts, Gauri Phadke

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Integrating the huge wiring harness network with the plastic trim components found in the car is an attractive way to reduce the vehicle weight. When any foreign object is inserted in an injection molded part, the change in polymer cross section leads to sink marks which are aesthetic defects and are not acceptable for plastic trim components.
In this thesis, a method to minimize or eliminate sink marks for wire insert molded component using injection molding process is presented. L9 Taguchi DOE experimental framework has been employed to study the effect of process parameters, part rib geometry, and the presence …

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