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Articles 241 - 270 of 371

Full-Text Articles in Mechanical Engineering

Numerical Analysis Of The Extrusion Of Fiber Optic And Photonic Crystal Fiber Preforms Near The Glass Transition Temperature, Mohamed Trabelssi May 2014

Numerical Analysis Of The Extrusion Of Fiber Optic And Photonic Crystal Fiber Preforms Near The Glass Transition Temperature, Mohamed Trabelssi

All Dissertations

Conventional clad core fiber optic technology has relied on a concentric structure of glass of different refraction indices. These conventional fibers suffer from constraints and limitations related to thermal expansion compatibility between the core and the glass. The new fiber technology broadly characterized as Microstructured Optic Fibers (MOFs) is intended to lift the limitations of conventional clad core fibers and also extend the range of application of fiber optics. Photonic Cristal Fibers(PCFs) are a special family of Microstructured Optic Fibers characterized by the presence of holes in the cross section of the fiber that are organized in a hexagonal pattern. …

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Inkjet Printing Of Three-Dimensional Vascular-Like Constructs From Cell Suspensions, Changxue Xu May 2014

Inkjet Printing Of Three-Dimensional Vascular-Like Constructs From Cell Suspensions, Changxue Xu

All Dissertations

Inkjet printing has found an increasing number of biofabrication applications, specifically organ printing, which has been emerging as a promising solution to the organ donor shortage. While some studies have been conducted to investigate various engineering problems associated with DOD inkjet printing of biological material-based fluids, the pinch-off, the cell-laden droplet formation, the effects of electric field on droplet formation, and challenges in 3D vascular-like construct fabrication haven't been systematically investigated. The objective of this study is to investigate the pinch-off, the cell-laden droplet formation, the effects of electric field on droplet formation, and manufacturing challenges during fabrication using DOD …

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Adaptive And Robust Braking-Traction Control Systems, John Adcox May 2014

Adaptive And Robust Braking-Traction Control Systems, John Adcox

All Dissertations

The designs of commercial Anti-Lock Braking Systems often rely on assumptions of a torsionally rigid tire-wheel system and heavily rely on hub-mounted wheel speed sensors to manage tire-road slip conditions. However, advancements in high-bandwidth braking systems, in-wheel motors, variations in tire/wheel designs, and loss of inflation pressure, have produced scenarios where the tire's torsional dynamics could be easily excited by the braking system actuator. In these scenarios, the slip conditions for the tire-belt/ring will be dynamically different from what can be inferred from the wheel speed sensors. This dissertation investigates the interaction of tire torsional dynamics with ABS & traction …

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Phonon Transport Analysis Of Semiconductor Nanocomposites Using Monte Carlo Simulations, Mayank Malladi Dec 2013

Phonon Transport Analysis Of Semiconductor Nanocomposites Using Monte Carlo Simulations, Mayank Malladi

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Nanocomposites are composite materials which incorporate nanosized particles, platelets or fibers. The addition of nanosized phases into the bulk matrix can lead to significantly different material properties compared to their macrocomposite counterparts. For nanocomposites, thermal conductivity is one of the most important physical properties. Manipulation and control of thermal conductivity in nanocomposites have impacted a variety of applications. In particular, it has been shown that the phonon thermal conductivity can be reduced significantly in nanocomposites due to the increase in phonon interface scattering while the electrical conductivity can be maintained. This extraordinary property of nanocomposites has been used to enhance …

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Analyzing Requirement Type Influence On Generated Solutions, Emily Worinkeng Dec 2013

Analyzing Requirement Type Influence On Generated Solutions, Emily Worinkeng

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Several ideation methods are available and used by engineering designers to enable the generation of alternative designs [1]. However, there has been little work done to understand the role that the design problem given to participants plays in the ideation process. The contribution of this research is found through the proposed guidelines with respect to the type of requirements to include as part of the design problem in order to achieve the desired quantity, quality, novelty, and variety of solutions during the early stages of the design process. This work is the first attempt at analyzing the effect of requirement …

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A Study Of Gallery Method To Increase Idea Quality In Conceptual Design, Liz Mathew Dec 2013

A Study Of Gallery Method To Increase Idea Quality In Conceptual Design, Liz Mathew

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The objective of this research is to evaluate whether gallery method increases idea quality in conceptual design for engineering design problems. The gallery method is a group ideation process which allows individuals to first generate ideas individually, followed by pooling of ideas to conduct group ideation. Design engineers are often encouraged to work in groups to generate concepts and solutions for design problems. However, past research argues that individual ideation results in higher quality design concepts compared to the group ideation methods. The limitations of group ideation such as free riding, production blocking, evaluation apprehension, and goal incongruity are identified …

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An Exploratory Study On The Effects Of Goal Alignment, Interventions, And Motivational Factors On Innovative Engineering Design Projects, Blake Linnerud Dec 2013

An Exploratory Study On The Effects Of Goal Alignment, Interventions, And Motivational Factors On Innovative Engineering Design Projects, Blake Linnerud

All Theses

Innovation has become an important facet of engineering design, both in industry and the academy. Many senior-level engineering design courses encourage students to develop innovative solutions to open design projects from industry sponsors. Like industry, these academic problems are tackled by teams of students. Student teams that function at the highest level are more likely to reach the innovative solutions for which they are searching. The research presented in this work focuses on two main areas: (1) understanding what motivates engineers when working on innovative design projects and (2) determining the effects of goal alignment interventions on design teams working …

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Knowledge Extraction From Work Instructions Through Text Processing And Analysis, Abhiram Koneru Dec 2013

Knowledge Extraction From Work Instructions Through Text Processing And Analysis, Abhiram Koneru

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The objective of this thesis is to design, develop and implement an automated approach to support processing of historical assembly data to extract useful knowledge about assembly instructions and time studies to facilitate the development of decision support systems, for a large automotive original equipment manufacturer (OEM). At a conceptual level, this research establishes a framework for sustainable and scalable approach to extract knowledge from big data using techniques from Natural Language Processing (NLP) and Machine Learning (ML). Process sheets are text documents that contain detailed instructions to assemble a portion of the vehicle, specification of parts and tools to …

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Effects Of Iteration On Concept Development, Shivraj Ranganathan Dec 2013

Effects Of Iteration On Concept Development, Shivraj Ranganathan

All Theses

Iteration in the conceptual design stage is defined as repetition of design tasks to incorporate new information. A more concise definition of iteration relevant to this research would be the progression of design through different abstraction levels or design stages, defining and refining design solutions while progressing from initial concepts to a more detailed design. Although it is believed that iteration has a positive effect on the quality of ideas in the design process, this experimental study presents an opportunity to determine the effects of iteration on quality of concepts and the factors that lead to increased quality of concepts. …

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Knowledge Base Representation With Axiomatic Design Rules For Concept Level Up Implement In Ontological Framework, Zhuochen Shi Dec 2013

Knowledge Base Representation With Axiomatic Design Rules For Concept Level Up Implement In Ontological Framework, Zhuochen Shi

All Theses

Axiomatic Design has been applied and developed as a tool, offering a scientific basis for design and improving design activities. Axiomatic Design has been used in various fields such as software system design, structure design, and product design. However, several challenges and limitations exist in Axiomatic Design including: the inconsistency in identifying design parameters, existence of coupled design, and multiple groups of functional requirements and design parameters. Aimed at using Axiomatic Design to generate conceptual solutions in engineering design while overcoming its limitations, a formal ontology is developed. The ontology defines functional requirements, design parameters, concepts, components and variables and …

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Enhancing Energy Efficiency In Connected Vehicles Via Access To Traffic Signal Information, Grant Mahler Dec 2013

Enhancing Energy Efficiency In Connected Vehicles Via Access To Traffic Signal Information, Grant Mahler

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This dissertation expounds on algorithms that can deterministically or proba-bilistically predict the future Signal Phase and Timing (SPAT) of a traffic signal by relying on real-time information from numerous vehicles and traffic infrastructure, historical data, and the computational power of a back-end computing cluster. When made available on an open server, predictive information about traffic signals’ states can be extremely valuable in enabling new fuel efficiency and safety functionalities in connected vehicles: Predictive Cruise Control (PCC) can use the predicted timing plan to calculate globally optimal velocity trajectories that reduce idling time at red signals and therefore improve fuel efficiency …

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Primary Resonance Behavior Of Expanded Polymer Cushion Material Under Low-Intensity Harmonic Excitations, Gregory Batt Dec 2013

Primary Resonance Behavior Of Expanded Polymer Cushion Material Under Low-Intensity Harmonic Excitations, Gregory Batt

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The demand to lower costs and reduce the amount of packaging materials utilized in a packaged-product system has placed increased importance on the development of tools to model the behavior of packaging systems. In this dissertation, the free and forced vibration response of a nonlinear, distributed-parameter model of a viscoelastic rod with an applied tip-mass is used to investigate the response of expanded polymer cushion materials to low-intensity harmonic excitations. The rod and tip-mass represent an idealized packaged product system. A nonlinear model is developed from constitutive relations. A classical Maxwell-Weichert model, represented via a Prony series, is used to …

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Understanding The Role Of Requirements In Engineering Design By Novices, Shraddha Joshi Dec 2013

Understanding The Role Of Requirements In Engineering Design By Novices, Shraddha Joshi

All Dissertations

Requirements play a critical role in the design process. The broader impact of this research is to develop a systematic understanding of the current use of requirements with an ultimate goal to develop guidelines and recommendations for more effective use of requirements throughout the design process. Thus, this research begins to answer the question about what is the role of requirements in design process and, specifically, its role in idea generation? The answer to this question is explored in three phases. The first phase is to understand how requirements are currently taught to students. To that end, two surveys were …

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Nonlinear Energy Harvesting Under White Noise, Qifan He Nov 2013

Nonlinear Energy Harvesting Under White Noise, Qifan He

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While purposeful introduction of stiffness nonlinearities into the dynamics of energy harvesters is aimed at enhancing performance under non-stationary and random excitations, most of the conclusions reported in the current literature are based on the steady-state response which assumes a harmonic fixed-frequency excitation. As a result, we still do not have a clear understanding of how the nature of the excitation influences the output power, or what role stiffness nonlinearities play in the transduction of energy harvesters under random excitations. To fill this gap in the current knowledge, this thesis investigates the response of nonlinear mono- and bi-stable energy harvesters …

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Moving Domain Computational Fluid Dynamics To Interface With An Embryonic Model Of Cardiac Morphogenesis, Juhyun Lee, Mahdi Esmaily Moghadam, Ethan Kung, Hung Cao, Tyler Beebe, Yury Miller, Beth L. Roman, Ching-Ling Lien, Neil C. Chi, Alison L. Marsden, Tzung K. Hsiai Aug 2013

Moving Domain Computational Fluid Dynamics To Interface With An Embryonic Model Of Cardiac Morphogenesis, Juhyun Lee, Mahdi Esmaily Moghadam, Ethan Kung, Hung Cao, Tyler Beebe, Yury Miller, Beth L. Roman, Ching-Ling Lien, Neil C. Chi, Alison L. Marsden, Tzung K. Hsiai

Publications

Peristaltic contraction of the embryonic heart tube produces time- and spatial-varying wall shear stress (WSS) and pressure gradients (∇P) across the atrioventricular (AV) canal. Zebrafish (Danio rerio) are a genetically tractable system to investigate cardiac morphogenesis. The use of Tg(fli1a:EGFP)y1 transgenic embryos allowed for delineation and two-dimensional reconstruction of the endocardium. This time-varying wall motion was then prescribed in a two-dimensional moving domain computational fluid dynamics (CFD) model, providing new insights into spatial and temporal variations in WSS and ∇P during cardiac development. The CFD simulations were validated with particle image …

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Particle Electrophoresis And Magnetophoresis In Microchannels, Litao Liang Aug 2013

Particle Electrophoresis And Magnetophoresis In Microchannels, Litao Liang

All Theses

In current pharmaceutical and biotechnology industries with clinical applications, an increased demand for flow control and cell manipulation on the micrometer scale has emerged. Electrokinetic, magnetic and many other physics fields have been exploited to meet this demand. However, due to the requirement for sophisticated micro-structures and the interference of the increasing significance of many `trivial' physics properties (surface potential, permittivity, etc.) at the smaller scale, most applications encounter poor maneuverability and high operation/fabrication complexity issues. Very few attempts have been made to bypass these requirements while maintaining the same control and efficiency. This thesis research investigates the fundamental behaviors …

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Topology Optimization Using A Level Set Penalization With Constrained Topology Features, Luis Fernandez Aug 2013

Topology Optimization Using A Level Set Penalization With Constrained Topology Features, Luis Fernandez

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Topology optimization techniques have been applied to structural design problems in order to determine the best material distribution in a given domain. The topology optimization problem is ill-posed because optimal designs tend to have infinite number of holes. In order to regularize this problem, a geometrical constraint, for instance the perimeter of the design (i.e., the measure of the boundary of the solid region, length in 2D problems or the surface area in 3D problems) is usually imposed. In this thesis, a novel methodology to solve the topology optimization problem with a constraint on the number of holes is proposed. …

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Computational Representation Of Linguistic Semantics For Requirement Analysis In Engineering Design, Alex Lash Aug 2013

Computational Representation Of Linguistic Semantics For Requirement Analysis In Engineering Design, Alex Lash

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The objective of this research is to use computational linguistics to identify semantic implicit relationships between text-based relationships. Specifically, natural language processing is used to implement linguistic semantics in requirement analyzers. Linguistic semantics is defined as the meaning of words beyond their string form, part of speech, and syntactic function. Many existing design tools use part of speech tagging and sentence parsing as the foundation of their requirement analysis but ultimately use string algorithms to evaluate requirements. These string algorithms cannot capture the implicit knowledge in requirements. This research compares five methods of requirement analysis. A manual analysis provides the …

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Design Optimization Of Geometrical Parameters And Material Properties Of Vibrating Bimorph Cantilever Beams With Solid And Honeycomb Substrates For Maximum Energy Harvested, Jasmin Adeshara Aug 2013

Design Optimization Of Geometrical Parameters And Material Properties Of Vibrating Bimorph Cantilever Beams With Solid And Honeycomb Substrates For Maximum Energy Harvested, Jasmin Adeshara

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The objective of this thesis is to maximize the energy harvested from a vibrating bimorph cantilever beam by optimizing the geometrical parameters and the material properties of the piezoelectric beam. A three-dimensional finite element (FEA) model is developed to design a vibrating bimorph cantilever beam for energy harvesting. The reference piezoelectric material used in the design is Lead Zirconate Titanate (PZT-5H) and the substrate sandwiched between the two piezoelectric plates is brass. Three types of models are analyzed and compared in this work by modifying the brass substrate geometry- a solid homogenous substrate, a regular honeycomb substrate and an auxetic …

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Finite Element Analysis Of Effective Mechanical Properties, Vibration And Acoustic Performance Of Auxetic Chiral Core Sandwich Structures, Hrishikesh Joshi Aug 2013

Finite Element Analysis Of Effective Mechanical Properties, Vibration And Acoustic Performance Of Auxetic Chiral Core Sandwich Structures, Hrishikesh Joshi

All Theses

Honeycomb cellular materials are widely used in engineering applications due to their high strength to weight ratio and controllable effective mechanical properties. The effective properties are controlled by varying the geometry of the repetitive unit cells of honeycomb structure. Sandwich panels made of honeycomb cores are beneficial in many applications including vibration isolation and sound transmission reduction. Sandwich panels with standard honeycomb core configurations have previously been studied with regards to sound transmission behavior. It has been established that the auxetic honeycomb cores, having negative in-plane Poisson's ratio, exhibit higher sound transmission loss as compared to regular honeycomb cores. In …

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Novel Side-Vent-Channel Based Blast Mitigation Concept For Light Tactical Vehicles, Ramin Yavari Aug 2013

Novel Side-Vent-Channel Based Blast Mitigation Concept For Light Tactical Vehicles, Ramin Yavari

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A new concept solution for improving survivability of the light tactical military vehicles to blast-loads resulting from a shallow-buried mine detonated underneath such vehicles is proposed and critically assessed using computational engineering methods and tools. The solution is inspired by the principle of operation of the rocket-engine nozzles, in general and the so called 'pulse detonation' rocket engines, in particular, and is an extension of the recently introduced so-called 'blast chimney' concept (essentially a vertical channel connecting the bottom and the roof and passing through the cabin of a light tactical vehicle).
Relative to the blast-chimney concept, the new solution …

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Model Based Control Of Machining Processes: Exploration Of Bayesian Statistical Methods For Identification And Control, Parikshit Mehta Aug 2013

Model Based Control Of Machining Processes: Exploration Of Bayesian Statistical Methods For Identification And Control, Parikshit Mehta

All Dissertations

Machining process modeling & simulation as well as in-process monitoring and control have been identified as key technological factors to power efficient manufacturing facilities of tomorrow. The effective utilization of process models and in-process control are aimed towards improving profitability of the manufacturing process. To that end, the objective of this research work is to improve machining performance by implementing in-process control using model based control strategies, while considering stochastic models of machining process. Towards satisfying that objective, three research questions are asked.
1) What are metrics of measuring machining performance and which machining process models are important to consider …

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Jet Instability And Droplet Formation For Bio-Printing Applications, Leigh Herran Aug 2013

Jet Instability And Droplet Formation For Bio-Printing Applications, Leigh Herran

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The research conducted in this dissertation was done to obtain a fundamental understanding of the formation of droplets in a drop-on-demand (DOD) inkjetting setup when the ink contains a polymer additive. The objective is to precisely control and even predict the forming dynamics and final droplet characteristics (velocity, size and satellite elimination). A polymeric fluid called sodium alginate has been gaining attention due to its highly bio-compatible nature. Solutions of sodium alginate were used as the ink material and in some cases compared with an equivalent Newtonian fluid (same zero-shear viscosity). The droplets were inspected in one of two ways: …

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Development Of Stationary And Mobile Tailgating Detection Solutions For Ground Vehicles, Tyler Zellmer Aug 2013

Development Of Stationary And Mobile Tailgating Detection Solutions For Ground Vehicles, Tyler Zellmer

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Improving the safety of North American roadways is a top priority for government agencies and transportation organizations alike. Regulations on appropriate driving behavior have been developed to minimize the likelihood of crashes occurring, but law enforcement tools remain to be fully developed and applied in the field. One prominent example of this is tailgating – the dangerous act of one ground vehicle following another too closely. This activity is responsible for thousands of crashes every year, but police officers currently have few tools to accurately detect and document tailgating events. Though tailgating often occurs in a wide variety of vehicle …

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Assessment Of An Automotive Driving Simulator To Educate Novice Drivers, John Wagner, Qimin Yao, Kim Alexander, Philip Pidgeon May 2013

Assessment Of An Automotive Driving Simulator To Educate Novice Drivers, John Wagner, Qimin Yao, Kim Alexander, Philip Pidgeon

Publications

Novice drivers are more likely to be involved in vehicle crashes than more experienced drivers. Transportation system simulators, such as aerospace, automotive, and rail, have been used effectively over several decades in support of operator training and research studies. The immersive high-end automotive simulators tend to be large-scale, difficult to move, and relatively cost ineffective for widespread deployment. In contrast, a mobile vehicle training system often features simplistic environments which are not readily accepted by teenagers who evaluate the driving experience as compared to commercial video games. Consequently, a need exists for a low-cost portable automotive training system that provides …

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Focused Novice Driver Program - Assessment Results And Discussion, John Wagner, Lance Clark, Kim Alexander, Philip Pidgeon, Ken Rogich May 2013

Focused Novice Driver Program - Assessment Results And Discussion, John Wagner, Lance Clark, Kim Alexander, Philip Pidgeon, Ken Rogich

Publications

Skills and experiences of novice drivers do not favorably compare to motorists with significantly greater driving time and life experiences. Recent developments in driver education and training have focused on multistage instruction to take advantage of the time delay for driving privileges in Graduated Driver Licensing (GDL) systems as a means to provide additional instruction. A supplemental safe driving program tailored to address the risky behaviors of novice drivers has been developed by Clemson University Automotive Safety Research Institute (CU-ASRI) and the Richard Petty Driving Experience (RPDE). The program offers training in anticipatory safe driving strategies based on the leading …

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Stability Control Of Triple Trailer Vehicles, Michael O'Neal Arant May 2013

Stability Control Of Triple Trailer Vehicles, Michael O'Neal Arant

All Dissertations

While vehicle stability control is a well-established technology in the passenger car realm, it is still an area of active research for commercial vehicles as indicated by the recent notice of proposed rulemaking on commercial vehicle stability by the National Highway Traffic Safety Administration (NHTSA, 2012). The reasons that commercial vehicle electronic stability control (ESC) development has lagged passenger vehicle ESC include the fact that the industry is generally slow to adopt new technologies and that commercial vehicles are far more complex requiring adaptation of existing technology. From the controller theory perspective, current commercial vehicle stability systems are generally passenger …

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Vibration And Acoustic Properties Of Honeycomb Sandwich Structures Subject To Variable Incident Plane-Wave Angle Pressure Loads, Jiaxue Yan May 2013

Vibration And Acoustic Properties Of Honeycomb Sandwich Structures Subject To Variable Incident Plane-Wave Angle Pressure Loads, Jiaxue Yan

All Theses

Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural …

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Three-Dimensional Finite Element Analysis Of Sound Transmission Performance Of Honeycomb Sandwich Structures, Xin Wang May 2013

Three-Dimensional Finite Element Analysis Of Sound Transmission Performance Of Honeycomb Sandwich Structures, Xin Wang

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Due to the lighter weight of honeycomb structures compared with a cuboid of similar material, honeycomb is widely used in applications requiring a high stiffness to weight ratio. One important honeycomb meta-structure is sandwich composites designed with a honeycomb core between two thin panel layers. The geometry of the honeycomb is formed from periodically spaced, non-overlapping unit cells. An important advantage of cellular materials such as honeycomb is that vibration and acoustic properties can be changed simply by changing the unit cell geometry variables such as included angle, cell wall thickness and length, while keeping the overall dimensions of the …

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Decision Support Systems For Assembly Line Planning -Modular Subsytems For A Large Scale Production Management System, Rahul Renu May 2013

Decision Support Systems For Assembly Line Planning -Modular Subsytems For A Large Scale Production Management System, Rahul Renu

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In the domain of assembly lines, process sheets are entities that carry assembly process descriptions (work instructions), assembly time estimations, product workspaces and other configuration management and control information. These process sheets get assigned to workstations during the process of assembly line balancing. In this research two tools have been developed to aid in the assembly line planning process. In order to ensure that assembly line workers do not intrude upon each other's workspace, two assembly processes operating on the same product workspace must not be assigned to the same station. Generating and maintaining product workspace information for every process …

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