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Articles 5911 - 5940 of 29986

Full-Text Articles in Mechanical Engineering

Multistage Modeling Of Fatigue Of Ti-6al-4v Fabricated By Different Additive Manufacturing Techniques, Lionardo Lado, Saeed Ataollahi, Mohammad J. Mahtabi May 2022

Multistage Modeling Of Fatigue Of Ti-6al-4v Fabricated By Different Additive Manufacturing Techniques, Lionardo Lado, Saeed Ataollahi, Mohammad J. Mahtabi

Honors Theses

Thanks to its high strength-to-weight ratio and corrosion resistance, Ti-6Al-4V has gained a lot of attention in additive manufacturing (AM) of complex parts with aerospace and medical applications. The realistic loading condition in these applications is mostly cyclic. However, the main challenge with AM of this alloy - and in general AM of metallic parts - is fatigue resistance and durability of the part, which has been reported to be much lower than the conventional materials. In this study, fatigue life performance of three additive manufacturing methods was compared using the Multistage Fatigue model (MSF). MSF model predicts the fatigue …

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The Grate Solution: Simplifying Viking Oven Packaging Processes, Megan Jansen May 2022

The Grate Solution: Simplifying Viking Oven Packaging Processes, Megan Jansen

Honors Theses

The following report details work completed to improve the Viking Oven Corporation’s gas oven assembly line. The current state of the line hosts an unreliable system for packaging oven grates. Viking manufactures two types of gas ovens on the same line: open burner and closed burner. These different types require different prepackaged grates to be included in the final assembly area. Viking estimates that the wrong grates are sent to the customer ten percent of the time. The following report presents research, brainstorming, problem-solving techniques, and proposed solutions to the problem. The proposed solution would solve the problem at little …

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Investigating The Application Of Flettner Rotors On The Great Lakes, Garrett C. Bond May 2022

Investigating The Application Of Flettner Rotors On The Great Lakes, Garrett C. Bond

Senior Honors Theses

Climate change is quickly becoming one of the leading problems of the twenty-first century, and the maritime transportation sector is beginning to react. Wind propulsion technologies have been making a comeback led by the Flettner rotor. The deck-mounted, vertical, spinning cylinder generates a lift (or thrust) force perpendicular to the wind by utilizing the Magnus effect. Rotor performance has been studied extensively on many ocean shipping routes, but has not been on the Great Lakes, a region with a large maritime industry. This study aims to assess whether or not Flettner rotors are practical in the region by calculating propulsive …

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Properties Of 25cr7ni Stainless Steel Fabricated Through Laser-Powder Bed Fusion., Arulselvan Arumugham Akilan May 2022

Properties Of 25cr7ni Stainless Steel Fabricated Through Laser-Powder Bed Fusion., Arulselvan Arumugham Akilan

Electronic Theses and Dissertations

Stainless steel is a low carbon high alloyed system with higher concentrations of Cr& Ni, which impart high corrosion resistance to them. Alloys with approximately 25% Cr & 7% Ni in their chemical composition are commercially referred to as ‘Super Duplex Stainless Steel’. They have a unique phase composition of approximately 50% ferrite & 50% austenite, yielding a robust combination of high mechanical strength & corrosion resistance. They find extensive interest & application in the fields which demand a longer service life under intense mechanical / corrosive environment such as offshore oil rigs & pipelines in nuclear power plants. Traditional …

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Nucleate Boiling Under Different Gravity Values: Numerical Simulations & Data-Driven Techniques., Sandipan Banerjee May 2022

Nucleate Boiling Under Different Gravity Values: Numerical Simulations & Data-Driven Techniques., Sandipan Banerjee

Electronic Theses and Dissertations

Nucleate boiling is important in nuclear applications and cooling applications under earth gravity conditions. Under reduced gravity or microgravity environment, it is significant too, especially in space exploration applications. Although multiple studies have been performed on nucleate boiling, the effect of gravity on nucleate boiling is not well understood. This dissertation primarily deals with numerical simulations of nucleate boiling using an adaptive Moment-of-Fluid (MoF) method for a single vapor bubble (water vapor or Perfluoro-n-hexane) in saturated liquid for different gravity levels. Results concerning the growth rate of the bubble, specifically the departure diameter and departure time have been provided. The …

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Fluid Structure Interactions Within A Common Rail Diesel Injector., Russell Prater May 2022

Fluid Structure Interactions Within A Common Rail Diesel Injector., Russell Prater

Electronic Theses and Dissertations

The internal flow of a high-pressure diesel injector is simulated numerically to investigate the complex transient flow structures and the unsteady forces imparted to the injector needle that result from the asymmetric flow fields developed during operation. The gas-liquid two phase flow is simulated using a mixture model with the cavitation numerically modeled using the Zwart-Gerber-Belamri model. Both the k-ε model and the detached eddy simulation (DES) model are used, and the numerical results are compared. This dissertation looks at the internal flow of a generic injector at different lifts and characterizes the flow parameters at high lift and low …

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Generative Designs Of Lightweight Air-Cooled Heat Exchangers, Connor Miller May 2022

Generative Designs Of Lightweight Air-Cooled Heat Exchangers, Connor Miller

Mechanical Engineering Undergraduate Honors Theses

The development of high-performance air-cooled heat exchangers is required to permit the rapid growth of vehicle and aircraft electrification. In electric vehicles and airliners, the motors and power electronics are integrated into a compact space, leading to unprecedently high power density. To achieve higher overall thermal efficiency, the heat exchangers must be extremely light while maintaining their heat transfer performance and mechanical robustness. Recently advances in 3D metal printing, e.g., direct metal laser sintering, and selective laser melting, have enabled the manufacturing of high-performance robust heat exchangers by eliminating thermal boundary resistance and ensuring a uniform thermal expansion coefficient. Nonetheless, …

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Durability Of Non-Metallic Materials For Additively Manufactured Heat Spreader Fabrication, Rafael Estrella May 2022

Durability Of Non-Metallic Materials For Additively Manufactured Heat Spreader Fabrication, Rafael Estrella

Mechanical Engineering Undergraduate Honors Theses

Power electronics are necessary to convert power from DC sources for AC applications. As this technology trends toward smaller packaging for denser power loads, the increased electrical losses result in deleterious excess heat. Thermal management devices are required to prevent the effects of thermal runaway from shortening the longevity of these modules. Nonmetallic jet impingement heat spreaders provide several benefits in terms of weight and performance over conventional cold plates while not accentuating EMI from the switches in the power module; however, the polymer makeup of the materials previously used for fabricating these devices raises durability concerns under the high …

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Autonomous Material Refill For Swarm 3d Printing, William C. Jones May 2022

Autonomous Material Refill For Swarm 3d Printing, William C. Jones

Mechanical Engineering Undergraduate Honors Theses

3D printing currently offers robust and cheap rapid prototyping solutions. While standard 3D printing remains at the periphery of mass production, the technology serves as a starting point for the development of swarm manufacturing. Since swarm manufacturing is predicated upon autonomy, swarm technology companies such as AMBOTS are seeking to minimize human involvement in the swarm’s functions. At present, the 3D printing swarm consists of the printers, a transporter which can take them between job sites, and the floor tiles which provide power and support the build surfaces. To add to this ecosystem, this project is focused on the design …

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Suitability Of Low-Cost Additive Manufacturing For Polymer Electrolyte Fuel Cells, David Alexander May 2022

Suitability Of Low-Cost Additive Manufacturing For Polymer Electrolyte Fuel Cells, David Alexander

Open Access Theses & Dissertations

The purpose of this dissertation is to study the feasibility of low-cost additive manufacturing to fabricate polymer electrolyte fuel cell bipolar plate materials. Traditional manufacturing techniques include molding, milling, hollow embossing, hydro-forming, rolling, and electromagnetic forming. These processes are employed when a design has been selected due to higher costs at low volumes. The combination of high initial costs and bipolar plates being the most expensive component of the polymer electrolyte fuel cell creates incentive to mitigate this obstacle. The feasibility of low-cost additive manufactured bipolar plates will be proven by fabrication, post-processing, and characterization of printed test specimen. The …

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Material Synthesis And Additive Manufacturing Of Ceramics, Elsa Bramasco-Rivera May 2022

Material Synthesis And Additive Manufacturing Of Ceramics, Elsa Bramasco-Rivera

Open Access Theses & Dissertations

This research is divided into two main topics: vitrimer polymers and alumina ceramics. Additive manufacturing is an emerging technology. In this research, two main methods of additive manufacturing are used: material extrusion and vat photopolymerization. The hypothesis of self-healing and mechanochromism functionalities was tested through the synthesis of vitrimers, a novel material combining properties of both thermosets and thermoplastics. These vitrimers were 3D printed using material extrusion. Casted vitrimers showed stiffening effects after submergence in water. Lithography based ceramics have gained attention in recent years due to their wide range of applications. Alumina ceramics were additively manufactured using digital light …

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Application Of The Continuum Damage Mechanics Wilshire-Cano-Stewart (Wcs) Model, Jaime Aaron Cano May 2022

Application Of The Continuum Damage Mechanics Wilshire-Cano-Stewart (Wcs) Model, Jaime Aaron Cano

Open Access Theses & Dissertations

In this study, the applications of the continuum damage mechanics-based Wilshire-Cano-Stewart (WCS) model are explored to predict rupture time, minimum-creep-strain-rate (MCSR), damage, damage evolution, and creep deformation. Increase knowledge in manufacturing methods has pushed the limit of material science and the development of new materials. Conventional testing is required to qualify materials against creep which according to the ASME B&PV III code, 10,000+ hours of experiments are necessary for each heat before materials are put into service. This process is costly and not feasible for new materials. As an alternative, models have been employed to predict creep behaviors and reduce …

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Femtosecond Laser Machining Of Drilled Holes In Silicon Nitride, Stephani Nevarez May 2022

Femtosecond Laser Machining Of Drilled Holes In Silicon Nitride, Stephani Nevarez

Open Access Theses & Dissertations

In this study, the laser drilling parameters of a Nd:YAG ultrashort pulsed laser are evaluated to produce zero taper through holes on silicon nitride ceramics. Manufacturing of ceramics is expensive and difficult because of the mechanical and thermal properties of ceramics, limiting applications. Additionally, the high level hardness of the ceramic can affect the ceramic and the manufacturing tool. There is a need to explore non-contact machining such as laser machining to expand the uses of ceramics in industry applications.In order to accomplish this goal, understanding of the physical mechanisms that occurs while laser ablation is needed. Furthermore, the minimum …

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All-In-One Multi3d System: Exploring Potential Of 5-Axis Material Extrusion Additive Manufacturing, Angel Vega May 2022

All-In-One Multi3d System: Exploring Potential Of 5-Axis Material Extrusion Additive Manufacturing, Angel Vega

Open Access Theses & Dissertations

Additive Manufacturing (AM) has experienced consistent growth since its inception across its seven process categories, especially Material Extrusion (MEX) with systems that can be seen in commercial and industrial settings. As MEX evolves, innovation can be traced in the growing variety of available process materials and new system capabilities leading to greater interest in the technology across various industries including automotive, aerospace and even nuclear weapons. This has created an increasing demand for end-use parts from MEX systems leading to more complex machines with additional Degrees of Freedom (DoF), specialized workflows, and expanded post processing that address the drawbacks of …

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Effects Of Sizing Agents On Mechanical Properties Of Carbon Fiber–Polymer Composites Via Fused Filament Fabrication Additive Manufacturing., Benjamin D. Mitchell May 2022

Effects Of Sizing Agents On Mechanical Properties Of Carbon Fiber–Polymer Composites Via Fused Filament Fabrication Additive Manufacturing., Benjamin D. Mitchell

Electronic Theses and Dissertations

This study demonstrated the effects of changing the sizing agent parameter during the preparation of carbon fibers on the mechanical properties of composite made with acrylonitrile butadiene styrene (ABS) as the matrix material and carbon fibers as the fiber material. Three types of sizing agents produced by Allnex were used to coat three different batches of carbon fibers that were mixed with a torque rheometer and extruded with a barrel-style melt extruder into continuous spools of 1.75 mm filament for use with commercial 3D printers. Tensile tests were conducted on the filaments and tensile bars printed from the materials. Results …

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Ng-Torque/Tension Testing Of Bolts With Epoxy Primer, Gabrielle Van Brunt May 2022

Ng-Torque/Tension Testing Of Bolts With Epoxy Primer, Gabrielle Van Brunt

Undergraduate Honors Capstone Projects

This capstone project is in conjunction with Northrop Grumman (NG). The goal of the project is for NG to apply an epoxy in the future to aerospace structures that they produce. This epoxy is meant to prevent corrosion of threaded joints in the structures. Although NG has the epoxy and has no issues procuring it, NG does not know the properties of the epoxy; it cannot be used until the epoxy’s nut factor is experimentally determined. The epoxy nut factor will be used for design and drawing purposes on various projects. To determine the nut factor, the Aggiepoxy team created …

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Material Synthesis And Machine Learning For Additive Manufacturing, Jaime Eduardo Regis May 2022

Material Synthesis And Machine Learning For Additive Manufacturing, Jaime Eduardo Regis

Open Access Theses & Dissertations

The goal of this research was to address three key challenges in additive manufacturing (AM), the need for feedstock material, minimal end-use fabrication from lack of functionality in commercially available materials, and the need for qualification and property prediction in printed structures. The near ultraviolet-light assisted green reduction of graphene oxide through L-ascorbic acid was studied with to address the issue of low part strength in additively manufactured parts by providing a functional filler that can strengthen the polymer matrix. The synthesis of self-healing epoxy vitrimers was done to adapt high strength materials with recyclable properties for compatibility with AM …

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Triggering Thermal Runaway In Lithium-Ion Batteries, Chris John May 2022

Triggering Thermal Runaway In Lithium-Ion Batteries, Chris John

Honors Scholar Theses

The proliferation of lithium-ion batteries enables electric devices such as cell phones to electric vehicles to become a reality. A latent danger, however, exists in these batteries. Mechanical, thermal, or electrical damage can initiate a phenomenon known as thermal runaway (TR). This damage causes internal short circuits within the battery, releasing heat and triggering exothermic decomposition reactions. The battery will catch fire if rapid cooling is not present. While experimental designs exist for evaluating TR, significant safety hazards and impracticality may impede testing efforts. Finite element analysis, therefore, becomes a vital tool in modeling TR and mitigation techniques. However, there …

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Modelling And Development Of An Automated Ldpe Autoclave Reactor In Cfd For Revealing Ethylene Hot Spots, Eric Turman May 2022

Modelling And Development Of An Automated Ldpe Autoclave Reactor In Cfd For Revealing Ethylene Hot Spots, Eric Turman

Masters Theses

Computational Fluid Dynamics (CFD) was employed to develop a rigorous model of a low-density polyethylene (LDPE) autoclave reactor. Different numerical settings within the solver were evaluated to minimize false diffusion and to reflect the sensitive heat generation taking place during free radical polymerization. The rigorous CFD model employed reaction kinetics, Proportional Integral Derivative (PID) automated thermal management, and a rotating stirrer shaft. Validation was carried out to determine the sensitivity to time-step size, turbulence model, and grid resolution. Data were compared to an industrial scale plant autoclave to guide the development of CFD. Time-step independence was confirmed by comparing the …

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Electrically Conductive Bearing Adapter Polymer Pad For Use In Freight Railcar Service Applications, Jesse M. Aguilera May 2022

Electrically Conductive Bearing Adapter Polymer Pad For Use In Freight Railcar Service Applications, Jesse M. Aguilera

Theses and Dissertations

Many freight railcars rest on polymer adapter pads made of injection-molded Thermoplastic Polyurethane (TPU) polymers which feature two copper studs to provide electrical conductivity through the adapter pads, which power onboard systems. In service, pads experience impact and cyclic loading, resulting in wear and plastic compression of the copper studs. This leads to signal interruptions and periodic replacement of the polymer pads, which results in downtime due to maintenance and reduced reliability since pad failure is unpredictable. These limitations in the current design are the impetus to create an electrically conductive polymer adapter pad that does not rely on the …

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Railcar Wheel Impact Detection Utilizing Vibration-Based Wireless Onboard Condition Monitoring Modules, Marco A. Barrera May 2022

Railcar Wheel Impact Detection Utilizing Vibration-Based Wireless Onboard Condition Monitoring Modules, Marco A. Barrera

Theses and Dissertations

The current limitations in established rail transport condition monitoring methods have motivated the UTCRS railway research team at UTRGV to investigate a novel solution that can address these deficiencies through wired, onboard, and vibration-based analytics. Due to the emergence of the Internet of Things (IoT), the research team has now transitioned into developing wireless modules that take advantage of the rapid data processing and wireless communication features these systems possess. This has enabled UTCRS to partner with Hum Industrial Technology, Inc. to assist them in the development of their “Boomerang” wireless condition monitoring system. Designed to revolutionize the way the …

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Evaluation Of Accelerated Testing Methods To Predict The Effects Of Chemical Exposure On Mechanical Properties Of Polyester Composites In Municipal Wastewater Service, Roberto A. Garcia May 2022

Evaluation Of Accelerated Testing Methods To Predict The Effects Of Chemical Exposure On Mechanical Properties Of Polyester Composites In Municipal Wastewater Service, Roberto A. Garcia

Theses and Dissertations

Composite Access Products (CAP) is a company that is determined to replace traditional steel manhole covers with fiber reinforced polymer alternatives that have similar performance while also introducing several advantages. CAP can achieve this by manufacturing the polymer manhole covers using high-speed, high pressure compressing molding to produce lightweight, long-lasting, corrosive resistant covers. CAP’s composite covers have been approved for use by TXDOT in roadway zones. Despite this, they must now undergo more testing and verification for use in environments with highly corrosive elements such as sewage environments and waste processing plants. In these situations, the polymer manhole covers will …

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Machine Learning Based Aerodynamic Shape Optimization, Noe Martinez Jr. May 2022

Machine Learning Based Aerodynamic Shape Optimization, Noe Martinez Jr.

Theses and Dissertations

The coefficient of pressure distribution for various 2D airfoil geometries were found using source – vortex panel methods. The data obtained in these simulations was used in multiple machine learning models which would predict the airfoil geometry from a given coefficient of pressure distribution. The neural networks employed were fully connected feedforward networks with Levenberg – Marquardt backpropagation and one model employed Bayesian Regularization. A novel tool for optimizing airfoil shape for a given coefficient of pressure distribution was created which performed well during testing. These models serve as the first step in minimizing the conflict between aerodynamic and stealth …

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Self-Diverting Nanofluid In-Situ Gelled Acid For Matrix Acidizing Applications In Carbonate Formations, Javier Alejandro Perez May 2022

Self-Diverting Nanofluid In-Situ Gelled Acid For Matrix Acidizing Applications In Carbonate Formations, Javier Alejandro Perez

Theses and Dissertations

The main purpose of this project is to develop a nanofluid system that would help to divert the injected acid from the main flow regime into a relatively lower permeability zone and being able to dissolve the rock significantly. The system is meant to successfully create acidic gel in-situ after injecting the fluid in solution. It is expected that by altering either pH, temperature or amount of reactants, the viscosity of the fluid can be controlled so that the gel can be broken at a desired time.

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An Experimentally Validated Finite Element Model Of Thermal Transient Response Of A Railroad Bearing Adapter, Javier E. Arroyo May 2022

An Experimentally Validated Finite Element Model Of Thermal Transient Response Of A Railroad Bearing Adapter, Javier E. Arroyo

Theses and Dissertations

Wayside hot box detectors (HBDs) are devices used to determine the health of railcar components such as bearings, axles, and brakes by monitoring the radiated temperature form these components. HBDs have been instrumental in reducing rail derailments in the decade, but the number of non-verified bearing removals has increased significantly. To combat these limitations, researchers have opted to use wireless onboard sensor devices directly mounted on the bearing adapter. The wireless onboard health monitoring system developed by the University Transportation Center for Railway Safety (UTCRS) utilizes temperature and vibration sensors to detect the condition of rolling stock. However, because the …

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Cloth-Water Interaction For Air Humidification In Hdh Desalination, Alejandro Corona Martinez May 2022

Cloth-Water Interaction For Air Humidification In Hdh Desalination, Alejandro Corona Martinez

Theses and Dissertations

The humidification-dehumidification (HDH) desalination technology is a promising desalination process that has the potential to provide cost-effective and environmentally friendly saltwater desalination, especially when combined with renewable energy sources. The working principle mimics the natural hydrologic cycle, involving the evaporation of seawater into water vapor (humidification) and condensation into freshwater (dehumidification). HDH desalination can be land-based or ocean-based. Some of the advantages of ocean-based systems include removing pretreatment processes, utilization of ocean energy (i.e. thermal and kinetic), and eliminating brine production. This study focuses on the design and experimental testing of a novel humidifier …

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Machine Learning Tools In The Predictive Analysis Of Ercot Load Demand Data, Md Riyad Hossain May 2022

Machine Learning Tools In The Predictive Analysis Of Ercot Load Demand Data, Md Riyad Hossain

Theses and Dissertations

The electric load industry has seen a significant transformation over the last few decades, culminating in the establishment and implementation of electricity markets. This transition separates electric generation services into a distinct, more competitive sector of the industry, allowing for the introduction of greater unpredictability into the system. Forecasting power system load has developed into a core research area in power and energy demand engineering in order to maintain a constant balance between electricity supply and demand. The purpose of this thesis dissertation is to reduce power system uncertainty by improving forecasting accuracy through the use of sophisticated machine …

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Investigation Of A Simultaneaous Direct And Indirect Contact Dehumidifier Using Parallel Strings For Hdh Desalination, Josue Perez Perez May 2022

Investigation Of A Simultaneaous Direct And Indirect Contact Dehumidifier Using Parallel Strings For Hdh Desalination, Josue Perez Perez

Theses and Dissertations

Freshwater is a limited and precious resource. Currently, half a billion people in the world face sever water scarcity all year round. Humidification dehumidification (HDH) systems have received special attention among the variety of small-scale desalination technologies due to its potential to create affordable and sustainable seawater desalination, especially when combined with natural power sources such as waves, wind, and solar rays. Improvements in the development of HDH desalination systems have been achieved in recent years. Nonetheless, the improvements that have received most attention focus on solar heaters and humidifiers. Dehumidification systems have often been adapted from air conditioning condensation …

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Interpolation And Extrapolation Of Optimally Fitted Kinematic Error Model For Five-Axis Machine Tools, Le Ma, Douglas A. Bristow, Robert G. Landers May 2022

Interpolation And Extrapolation Of Optimally Fitted Kinematic Error Model For Five-Axis Machine Tools, Le Ma, Douglas A. Bristow, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Machine tool geometric errors are frequently corrected by populating compensation tables that contain position-dependent offsets to each commanded axis position. While each offset can be determined by directly measuring the individual geometric error at that location, it is often more efficient to compute the compensation using a volumetric error model derived from measurements across the entire axis space. However, interpolation and extrapolation of measurements, once explicit in direct measurement methods, become implicit and obfuscated in the curve-fitting process of volumetric error methods. The drive to maximize model accuracy while minimizing measurement sets can lead to significant model errors in workspace …

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Experimentation Of Abrasion Erosion At High Temperature For Concentrated Solar Power Systems, Tessa Mei-Lin Fong May 2022

Experimentation Of Abrasion Erosion At High Temperature For Concentrated Solar Power Systems, Tessa Mei-Lin Fong

Boise State University Theses and Dissertations

Concentrated solar power (CSP) is an alternative and sustainable way to produce energy. Studies have shown that running these plants at high temperatures above 700°C can increase the thermal efficiency in heat transfer. Molten salt is usually used as the heat transfer medium but cannot be used due to its low maximum temperature and high freezing point. Running these plants at high temperature brings up the concern of erosion and oxidation. Abrasion erosion occurs through the interaction of particles and material. The goal of this research is to understand material degradation due to abrasion erosion to understand the durability of …

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