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Articles 61 - 90 of 140
Full-Text Articles in Engineering Science and Materials
Friction Stir Welding Process And Material Microstructure Evolution Modeling In 2000 And 5000 Series Of Aluminum Alloys, Harshavardhan Yalavarthy
Friction Stir Welding Process And Material Microstructure Evolution Modeling In 2000 And 5000 Series Of Aluminum Alloys, Harshavardhan Yalavarthy
All Theses
Interactions between the rotating and advancing pin-shaped tool (terminated at one end with a circular-cylindrical shoulder) with the clamped welding-plates and the associated material and heat transport during a Friction Stir Welding (FSW) process are studied computationally using a fully-coupled thermo-mechanical finite-element analysis. To surmount potential numerical problems associated with extensive mesh distortions/entanglement, an Arbitrary Lagrangian Eulerian (ALE) formulation was used which enabled adaptive re-meshing (to ensure the continuing presence of a high-quality mesh) while allowing full tracking of the material free surfaces. To demonstrate the utility of the present computational approach, the analysis is applied to the cases of …
Straight Line Braking Performance Of A Road Vehicle With Non Linear Tire Stiffness Formulation, Anup Khekare
Straight Line Braking Performance Of A Road Vehicle With Non Linear Tire Stiffness Formulation, Anup Khekare
All Theses
The capability of a road vehicle equipped with an Anti-Lock Braking System (ABS) to come to a safe stop depends on factors such as dynamic force between tire and road, surface adhesion coefficient, and the vertical profile of the road. When in panic, a driver's reaction is to step hard on the brakes to make the vehicle stop as soon as possible. Although the use of modern technologies such as ABS and Electronic Stability Control (ESC) have reduced the number of accidents significantly, any further improvement in stopping distance would only complement these technologies.
Michelin has undertaken the development of …
The Effect Of A Surfactant Monolayer On Gas Exchange Across An Air-Water Interface During Mixed Convection, Richard Lee
The Effect Of A Surfactant Monolayer On Gas Exchange Across An Air-Water Interface During Mixed Convection, Richard Lee
All Theses
A set of laboratory experiments are presented that reveal the effect of a surfactant monolayer on the transport of oxygen across an air-water interface during mixed convection conditions. The experiments were conducted in a wind/water tunnel with water tanks of differing depth. Forced convection was imposed via the air flow, while natural convection was imposed by heating the water bulk above the air temperature. For the range of wind speeds being considered, mixed convection conditions resulted. Experiments were also conducted with only forced convection present. The data acquired during these experiments were used to develop a parameterization between the Sherwood …
Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal
Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal
All Theses
The purpose of this research is to determine the optimum process parameters for the Precision Glass Molding (PGM) Process using Manufacturing Design, Design of Experiments and Metrology (for measuring the geometry of lenses). First, a custom machine is designed and manufactured which can carry out Precision Glass Lens Molding Experiments. This machine is then modified to improve temperature, position and force control. A literature review is performed to obtain data for process parameters that have been used in previous PGM studies. The collected data is then used in Design of Experiments to create twenty seven experiments that determine the optimum …
Characterization And Enhancement Of Sensing Properties Of Piezoelectric Materials With Applications To Vibration Suppression, Siddharth Aphale
Characterization And Enhancement Of Sensing Properties Of Piezoelectric Materials With Applications To Vibration Suppression, Siddharth Aphale
All Theses
This thesis undertakes the study of piezoelectric properties of polymer-based fabric and film sensors. An enhancement in piezoelectric properties of such sensors, as noted through earlier work, is observed with increasing weight ratios of nanomaterials dispersed in the polymer matrix. A comprehensive mathematical model using cantilever beams is developed to analyze this enhancement both qualitatively and quantitatively. An experimental setup is also developed to implement the proposed real time signal processing necessary to collect required data towards the characterization. In order to distinguish piezoelectric materials from other materials, study of the frequency response of developed fabric sensors to periodic chirp …
On The Modeling Of Energy Harvesters And Analysis Of Their Response Under Time-Varying Frequency Excitations, Thiago Seuaciuc-Osorio
On The Modeling Of Energy Harvesters And Analysis Of Their Response Under Time-Varying Frequency Excitations, Thiago Seuaciuc-Osorio
All Theses
Energy harvesting is a process by which otherwise wasted ambient energy can be captured and transformed into a useful form. Historical examples of this concept include windmills, sailing ships, and waterwheels. Modern technologies and current energy needs have brought this same concept to a smaller scale wherein small wireless devices with minute energy consumption can be operated autonomously. Today, many critical electronic devices, such as health-monitoring sensors, pace makers, spinal stimulators, electric pain relievers, etc. require minimal amounts of power to function, which permits utilizing energy from their environment to power them. By exploiting the ability of active materials and …
Development Of A Rigid Ring Tire Model And Comparison Among Various Tire Models For Ride Comfort Simulations, Norm Frey
All Theses
One vehicle subassembly that is of great importance to automobile manufacturers for tuning final vehicle performance is the pneumatic tire. Pneumatic tires present themselves as unique tuning tools as they 1) are the sole link between the roadway surface and the integrated vehicle suspension, chassis and steering systems, and 2) provide a wide range of tunability over many vehicle performances, including handling (steering feel as well as chassis dynamics), traction (braking, driving, and cornering), and ride comfort (roadway isolation). Therefore the vehicle manufacturing industry continues to research and refine various aspects of tire modeling to improve up-front integrated tire/vehicle CAE/CAD …
Use Of Orthogonal Arrays For Efficient Evaluation Of Geometric Designs For Reducing Vibration Of A Non-Pneumatic Wheel During High-Speed Rolling, William Rutherford
Use Of Orthogonal Arrays For Efficient Evaluation Of Geometric Designs For Reducing Vibration Of A Non-Pneumatic Wheel During High-Speed Rolling, William Rutherford
All Theses
During high speed rolling of a non-pneumatic wheel, vibration may be produced by the interaction of collapsible spokes with a shear deformable ring as they enter the contact region, buckle and then snap back into a state of tension. In the present work, a 2D planar finite element model with geometric nonlinearity and explicit time-stepping is used to simulate rolling of the non-pneumatic wheel. Vibration characteristics are measured from the FFT frequency spectrum of the time-signals of perpendicular distance of marker nodes from the virtual plane of the spoke, thickness change in the ring between spokes, and ground reaction forces. …
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 …
Dynamic Finite Element Simulation Of Ultrasonic Consolidation, Daniel Mccullough
Dynamic Finite Element Simulation Of Ultrasonic Consolidation, Daniel Mccullough
All Theses
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 …
Predictive Energy Management In Smart Vehicles: Exploiting Traffic And Traffic Signal Preview For Fuel Saving, Behrang Asadi
Predictive Energy Management In Smart Vehicles: Exploiting Traffic And Traffic Signal Preview For Fuel Saving, Behrang Asadi
All Theses
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 …
A Study In The Information Content, Consistency, And Expressive Power Of Function Structures In Mechanical Design, Chiradeep Sen
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 …
A Priori Analysis Of Subgrid Scalar Phenomena And Mass Diffusion Vectors In Turbulent Hydrogen-Oxygen Flames, Justin Foster
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 …
Development Of A Nonlinear Ride Quality Model To Aid In Tweelå© Parameter Selection, Marc Paradiso
Development Of A Nonlinear Ride Quality Model To Aid In Tweelå© Parameter Selection, Marc Paradiso
All Theses
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 …
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 …
An Evaluation Of Function-Based Representations And Information Archival In Engineering Design, Benjamin Caldwell
An Evaluation Of Function-Based Representations And Information Archival In Engineering Design, Benjamin Caldwell
All Theses
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 …
Taxonomy Of Physical Prototypes: Structure And Validation, Ashwin Michaelraj
Taxonomy Of Physical Prototypes: Structure And Validation, Ashwin Michaelraj
All Theses
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 …
Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal
Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal
All Theses
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 …
Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora
Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora
All Theses
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. …
An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan
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 …
Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling
Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling
All Theses
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 …
Nonlinear Finite Element Analysis Of Tweel Geometric Parameter Modifications On Spoke Dynamics During High Speed Rolling, Maya Ramachandran
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 …
Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson
Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson
All Theses
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 …
Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg
Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg
All Theses
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 …
Non-Linear Finite Element Analysis And Optimization For Light Weight Design Of An Automotive Seat Backrest, Prasanna Balaji Thiyagarajan
Non-Linear Finite Element Analysis And Optimization For Light Weight Design Of An Automotive Seat Backrest, Prasanna Balaji Thiyagarajan
All Theses
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 …
Analysis Of Non Load Bearing Two Component (2k) Adhesives; Under The Automotive Hemming Process Variations; Thermogravimetric, Calorimetric And Composition Analyses, Kameswara Nara
All Theses
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 …
Quantitative Modeling Of Soil Properties Based On Composition And Application To Dynamic Tire Testing, Sumalatha Yaski
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 …
Three Design Tool Focused Case Studies Of Mechanical Engineering Design Projects, William Miller
Three Design Tool Focused Case Studies Of Mechanical Engineering Design Projects, William Miller
All Theses
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 …
Enhancement Of Information Management Capabilities In Mdo Framework, Santosh Hiriyannaiah
Enhancement Of Information Management Capabilities In Mdo Framework, Santosh Hiriyannaiah
All Theses
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 …
Reduction Of Sink Marks In Wire Insert Molded Parts, Gauri Phadke
Reduction Of Sink Marks In Wire Insert Molded Parts, Gauri Phadke
All Theses
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 …