Engineering Commons^™

Floating Wind Farm Experiments Through Scaling For Wake Characterization, Power Extraction, And Turbine Dynamics, Juliaan Bossuyt, OndˇRej FercˇÁk, Zein Sadek, Charles Meneveau, Dennice Gayme, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

In this study, wind and water tunnel experiments of turbulent wakes in a scaled floating wind farm are performed. Scaling of a floating wind farm with a scaling ratio of 1:400 is made possible by relaxing geometric scaling of the turbine platform system, such that the dynamic response can be correctly matched, and to allow for relaxing Froude scaling such that the Reynolds number can be kept large enough. Four dimensionless parameters, describing the relative importance of wind and wave loads compared to turbine inertia, are used to guide the scaled floater design. Free decay tests of the pitch and …

Uncovering Transient Dynamics And Equilibrium States Of Particle Aggregates With RaúL BayoáN Cal, RaúL BayoáN Cal

PDXPLORES Podcast

In this episode of PDXPLORES, Raúl Bayoán Cal, Professor of Mechanical & Materials Engineering at the Maseeh College of Engineering and Computer Science, discusses his latest National Science Foundation award-winning research, Uncovering Transient Dynamics and Equilibrium States of Particle Aggregates in Fluids, investigating transient dynamics of fluid mechanics in the absence of gravity. These experiments, which utilize the Dryden Drop Tower and research facilities aboard the International Space Station, will benefit the study of granular media in aggregation models such as pollen deposition, algae growth, and plastic pollution.

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Flow In Additively Manufactured Super-Rough Channels, Samuel Altland, Xiaowei Zhu, Stephen Mcclain, Robert Kunz, Xiang Yang

Mechanical and Materials Engineering Faculty Publications and Presentations

Metal additive manufacturing has enabled geometrically complex internal cooling channels for turbine and heat exchanger applications, but the process gives rise to large-scale roughness whose size is comparable to the channel height (which is 500 μm). These super-rough channels pose previously unseen challenges for experimental measurements, data interpretation and roughness modelling. First, it is not clear if measurements at a particular streamwise and spanwise location still provide accurate representation of the mean (time- and plane-averaged) flow. Second, we do not know if the logarithmic layer survives. Third, it is unknown how well previously developed rough-wall models work for these large-scale …

Materials And Methodologies For Spectroscopic And Optical Analytical Applications In Cultural Heritage Conservation Science, Lyndsay Nichole Kissell

Dissertations and Theses

The field of conservation science falls in the intersection of science and art. The work of conservation scientists may include any single subdiscipline of chemistry, though it is most commonly a highly interdisciplinary field taking skills from analytical, organic, and inorganic chemistry, as well as surface and materials science. The aims of conservation scientists are to answer questions about the production and aging of material cultural heritage. Knowing the materials used by an artist can lead to insight about the intentions of the object and knowing how those materials degrade will enable the use of preventative measures to ensure the …

Random Lasing In Nano-Crystalline Zinc-Oxide Films, Benito Reynaldo Resendiz

Dissertations and Theses

In this thesis, we explore the preparation of random lasers (RLs) using solution-deposited, randomly packed nano-particle films of zinc oxide (ZnO) impregnated with silicon dioxide (SiO₂) nanospheres. RLs have their scatterers randomly oriented, while their lasing comes from light propagating along closed paths through the scattering environment. It is shown here that random lasing is readily observed in films made of submicron sized ZnO particles. Adding transparent SiO₂ nanospheres to the films, we show there is an effective improvement of the lasing that is observable in all of the samples spectra. Specifically, we found that the lasing …

Improved Predictive Modeling Techniques For Non-Linear Solder Material Behavior, Arman Millian Ahari

Dissertations and Theses

Accurate prediction of fatigue life of solder joints in electronic packaging applications becomes of critical importance as semiconductor device technology and manufacturing constraints grow in complexity. To gain visibility on IC device performance and reliability, thermo-mechanical simulation is performed based on a unified, viscoplastic material model, which is dependent on nine parameters.

In this study, an improved method of Anand parameter extraction, which involves curve-fitting non-linear experimental stress data, is proposed to improve the accuracy of numerical predictions for solder reliability. Theoretical equations for uni-axial stress-strain response and creep response are derived, then details on their relevance to experimental and …

Optimization Of 3d Printed Mold Performance For Injection Molding Via Hollow Infill Patterns, Alan Fong

University Honors Theses

The applicability of hollow infill patterns has been explored for its applications in making 3D printed polymer-based injection molds in the additive manufacturing industry. Hollow infill patterns offer a significant reduction in material costs as well as the opportunity for reducing the cooling times via pumping a coolant fluid through the hollow cavity in a similar fashion to traditional conformal cooling channels. A 3D Jacks Support Hollow mold model was determined to be the best performing design. FEA analysis was conducted to determine the maximum reduction in internal volume (percentage of material saved) that could be achieved without exceeding the …

Impact Of Green And White Roofs On Air Handler Filters And Indoor Ventilation Air, Pradeep Ramasubramanian, Irvan Luhung, Serene B. Y. Lim, Stephan C. Schuster, Olyssa Starry, Elliott T. Gall

Mechanical and Materials Engineering Faculty Publications and Presentations

Rooftop surfaces near building outdoor air intakes may contribute to the mass loading on filters and compounds emitted to ventilation air downstream of the filter. In laboratory analyses, we characterized microbial composition, primary volatile organic compound (VOC) emissions, ozone removal rates, and VOC emissions in the presence of ozone on filters collected from air handlers located on the green and white roof sections of a big-box retail store. Total DNA masses per area of filter were 26.3 ± 11.9 ng cm−2 and 6.3 ± 6.5 ng cm−2 for green and white roof filters respectively, with higher mass observed in winter …

A Three-Dimensional Musculoskeletal Model Of The Dog, Heiko Stark, Martin S. Fischer, Alexander Hunt, Fletcher Young, Roger Quinn, Emanuel Andrada

Mechanical and Materials Engineering Faculty Publications and Presentations

Abstract The domestic dog is interesting to investigate because of the wide range of body size, body mass, and physique in the many breeds. In the last several years, the number of clinical and biomechanical studies on dog locomotion has increased. However, the relationship between body structure and joint load during locomotion, as well as between joint load and degenerative diseases of the locomotor system (e.g. dysplasia), are not sufficiently understood. Collecting this data through in vivo measurements/records of joint forces and loads on deep/small muscles is complex, invasive, and sometimes unethical. The use of detailed musculoskeletal models may help …

Lagrangian Diffusion Properties Of A Free Shear Turbulent Jet, Bianca F. Viggiano, Thomas Basset, Stephen Solovitz, Thomas Barois, Mathieu Gibert, Nicolas Mordant, Laurent Chevillard, Romain Volk, Mickael Bourgoin, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

A Lagrangian experimental study of an axisymmetric turbulent water jet is performed to investigate the highly anisotropic and inhomogeneous flow field. Measurements are conducted within a Lagrangian exploration module, an icosahedron apparatus, to facilitate optical access of three cameras. Stereoscopic particle tracking velocimetry results in three-component tracks of position, velocity and acceleration of the tracer particles within the vertically oriented jet with a Taylor-based Reynolds number Reλ≃230. Analysis is performed at seven locations from 15 diameters up to 45 diameters downstream. Eulerian analysis is first carried out to obtain critical parameters of the jet and relevant scales, namely the Kolmogorov …

The Corrosion Of Stainless Steel Made By Additive Manufacturing: A Review, Gyeongbin Ko, Wooseok Kim, Kyungjung Kwon, Tae-Kyu Lee

Mechanical and Materials Engineering Faculty Publications and Presentations

The advantages of additive manufacturing (AM) of metals over traditional manufacturing methods have triggered many relevant studies comparing the mechanical properties, corrosion behavior, and microstructure of metals produced by AM or traditional manufacturing methods. This review focuses exclusively on the corrosion property of AM-fabricated stainless steel by comprehensively analyzing the relevant literature. The principles of various AM processes, which have been adopted in the corrosion study of stainless steel, and the corrosion behaviors of stainless steel depending on the AM process, the stainless steel type, and the corrosion environment are summarized. In this comprehensive analysis of relevant literature, we extract …

The Hot Cracking Susceptibility Subjected The Laser Beam Oscillation Welding On 6xxx Aluminum Alloy With A Partial Penetration Joint, Minjung Kang, Jason Cheon, Dong Hyuck Kam, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

A laser beam oscillation method using Galvano mirrors, which allows wide weld beads and controls thermal stress distribution, was suggested to suppress the formation of solidification cracks in laser welds. In order to understand the solidification cracking behavior in relation to the bead shape, laser beam oscillation welding was performed under various oscillation widths and frequency conditions. To evaluate the effect of the oscillation parameter on solidification cracking susceptibility, a regression analysis based on the shape of the bead was performed. Stress distribution generated during the laser beam oscillation welding process was also analyzed using finite element modeling simulation. From …

Development Of Graphene Synthesis And Characterization Techniques Toward Cmos Applications And Beyond, Otto Kno Zietz

Dissertations and Theses

Graphene exhibits mechanical and electrical properties which, coupled with its two dimensional (2D) morphology, make it an attractive material component for inclusion in a wide range of industries. Since the discovery of graphene in 2004, industry adoption has been limited due to the demanding synthesis requirements for high quality and connected graphene as well as the difficulties associated with direct incorporation. Chemical vapor deposition (CVD) has emerged as the most cost efficient method for producing high quality graphene at scales suitable for mass production. However, the 1000°C temperatures and micrometer thick catalysts required for this process preclude direct inclusion in …

Parametric Investigation Of Effect Of Abnormal Process Conditions On Self-Piercing Riveting, Taek-Eon Jeong, Dong-Hyuck Kam, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

Self-piercing riveting (SPR) is one of the mechanical joining processes, and its application to Al/Fe dissimilar materials combination, which is hard to weld, is expanding in the automotive industry. The main process parameters in SPR are types of rivet and die, setting force, and rivet setting speed. Previously, the relationship between the main process parameters and output parameters such as cross-sectional characteristics and joint strength has been studied to optimize the SPR process. In practical applications, there are unexpected and abnormal process conditions such as poor fit-up, angular misalignment, edge offset distance, and inaccurate setting and pre-clamping forces, and their …

Enhanced Carrier Transport By Transition Metal Doping In Ws2 Field Effect Transistors, Maomao Liu, Sichen Wei, Simran Shahi, Hemendra Nath Jaiswal, Paolo Paletti, Sara Fathipour, Maja Remskar, Jun Jiao, Wansik Hwang, Fei Yao, Huamin Li

Physics Faculty Publications and Presentations

High contact resistance is one of the primary concerns for electronic device applications of two-dimensional (2D) layered semiconductors. Here, we explore the enhanced carrier transport through metal–semiconductor interfaces in WS₂ field effect transistors (FETs) by introducing a typical transition metal, Cu, with two different doping strategies: (i) a “generalized” Cu doping by using randomly distributed Cu atoms along the channel and (ii) a “localized” Cu doping by adapting an ultrathin Cu layer at the metal–semiconductor interface. Compared to the pristine WS₂ FETs, both the generalized Cu atomic dopant and localized Cu contact decoration can provide a Schottky-to-Ohmic contact …

Ten Questions Concerning The Implications Of Carpet On Indoor Chemistry And Microbiology, Sarah R, Haines, Rachel I. Adams, Brandon E. Boor, Thomas A. Bruton, John Downey, Andrea R. Ferro, Elliott T. Gall, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

Carpet and rugs currently represent about half of the United States flooring market and offer many benefits as a flooring type. How carpets influence our exposure to both microorganisms and chemicals in indoor environments has important health implications but is not well understood. The goal of this manuscript is to consolidate what is known about how carpet impacts indoor chemistry and microbiology, as well as to identify the important research gaps that remain. After describing the current use of carpet indoors, questions focus on five specific areas: 1) indoor chemistry, 2) indoor microbiology, 3) resuspension and exposure, 4) current practices …

Potential Of Module Arrangements To Enhance Convective Cooling In Solar Photovoltaic Arrays, B. Stanislawski, Fabien Margairaz, Raúl Bayoán Cal, Marc Calaf

Mechanical and Materials Engineering Faculty Publications and Presentations

When solar photovoltaic (PV) module temperatures rise during operation, commonly-installed modules experience an efficiency loss between 0.1 and 0.5% per degree above 25+C. Thus, extensive research has aimed to reduce the operating temperature of solar modules. However, many cooling solutions require additional cost or equipment that precludes their implementation in utility-scale PV plants. Based on previous studies of land-atmosphere interactions of surface thermal heterogeneity, we hypothesize that certain solar farm arrangements may enhance natural convective heat transfer between the solar modules and surrounding flow. Due to the strong non-linear relationship between module temperature and convective heat transfer, enhancing the convective …

Utility-Scale Solar Pv Performance Enhancements Through System-Level Modifications, Andrew D. S. Glick, Naseem Ali, Juliaan Bossuyt, Marc Calaf, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Performance of solar PV diminishes with the increase in temperature of the solar modules. Therefore, to further facilitate the reduction in cost of photovoltaic energy, new approaches to limit module temperature increase in natural ambient conditions should be explored. Thus far only approaches based at the individual panel level have been investigated, while the more complex, systems approach remains unexplored. Here, we perform the first wind tunnel scaled solar farm experiments to investigate the potential for temperature reduction through system-level flow enhancement. The percentage of solar irradiance converted into electric power depends upon module efficiency, typically less than 20%. The …

Data-Driven Modeling Of The Wake Behind A Wind Turbine Array, Naseem Ali, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

The wake flow in a wind turbine array boundary layer is described using the Koopman operator. Dynamics of the flow are decomposed into the linear and forcing terms, and the low-energy delay coordinates are revealed. The rare events show the non-Gaussian long tails that capture the switching and bursting phenomena. The near-wake region shows the incoherent phase space region, where the dynamics are strongly nonlinear. The far-wake region is marked with the small non-Gaussian forcing term, and the dynamics are largely governed by linear dynamics. The data-driven predictive model is built based on the Hankel-based dynamic mode decomposition and treats …

Hot Deformation Data For Haynes 214, Haynes 230 And Inconel 740h, Benjamin Adam, Julie Tucker, Graham Tewksbury

Mechanical and Materials Engineering Faculty Publications and Presentations

This article presents the datasets gathered for the hot processing of three Ni-based superalloys intended for A-USC application, Haynes 214, Haynes 230 and Inconel 740H. Isothermal compression tests were conducted with a Gleeble 3500 at temperatures between 1000 C and 1200 C and strain rates between 0.01/s and 1/s to a full true strain of 0.7. The obtained true stress-true strain curves were used as basis for hot processing maps, linking temperature, stress and strain rate. Subsequently, all samples were sectioned through the geometric centre to provide microstructural information, captured using EBSD, as well as EDX for the evolution of …

The Optimized Synthesis Of Copper Nanowire For High-Quality And Fabrication Of Core-Shell Nanowire, Suhyun Lee

Dissertations and Theses

Flexible electronics are the promising technology for prospective application in foldable phones. Currently, indium tin oxide (ITO) has been widely used for electronic devices including flat-panel display. However, it is brittle and expensive. Metal nanowires are considered as alternative materials. Among various metal nanowires, copper nanowires are attractive because of its high electrical conductivity, better flexibility, and low cost compared with ITO. However, copper nanowires are very prone to oxidize, which causes subsequent degradation of electrical conductivity. Due to this oxidation issue, core-shell structure nanowires, which are formed silver shell having high conductivity and low resistivity on the surfaces of …

Contamination Of Coupling Glass And Performance Evaluation Of Protective System In Vacuum Laser Beam Welding, Yongki Lee, Jason Cheon, Byung-Kwon Min, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

Vacuum laser beam welding enables deeper penetration depth and welding stability than atmospheric pressure laser welding. However, contaminated coupling glass caused by welding fumes in the vacuum space reduces laser transmittance, leading to inconsistent penetration depth. Therefore, a well-designed protective system is indispensable. Before designing the protective system, the contamination phenomenon was quantified and represented by a contamination index, based on the coupling glass transmittance. The contamination index and penetration depth behavior were determined to be inversely proportional. A cylindrical protective system with a shielding gas supply was proposed and tested. The shielding gas jet provides pressure-driven contaminant suppression and …

Using Thermal Gradient Measurements To Compare Bath Temperature And Agitation Effects On The Quenching Performance Of Palm Oil, Canola Oil And A Conventional Petroleum Oil, Bozidar Matijevic, Bruno F. Canale, Božidar Lišcic, George Totten

Mechanical and Materials Engineering Faculty Publications and Presentations

A proprietary Liscic/Petrofer cylindrical Inconel 600 probe of 50-mm diameter and 200-mm length which was instrumented with three thermocouples on the same radius of the crosssection at the middle of the length was used to determine the differences in quenching performance of two vegetable oils, palm oil and canola oil, and they were compared to a locally produced conventional petroleum oil quenchant. The cooling curves and heat transfer performance of these oils were determined at different bath temperatures and agitation rates. The work was performed at the Quenching Research Centre located at the Faculty for Mechanical Engineering, University of Zagreb, …

X-Ray Determination Of Compressive Residual Stresses In Spring Steel Generated By High-Speed Water Quenching, Diego E. Lozano, George E. Totten, Yaneth Bedolla-Gil, Martha Guerrero-Mata, Marcel Carpio, Gabriela M. Martinez-Cazares

Mechanical and Materials Engineering Faculty Publications and Presentations

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core …

Effects Of Steel Type And Sandblasting Pretreatment On The Solid-Liquid Compound Casting Characteristics Of Zinc-Coated Steel/Aluminum Bimetals, Jesik Shin, Taehyeong Kim, Kyoungmook Lim, Hoon Cho, Daeho Yang, Changyeol Jeong, Sung Yi

Mechanical and Materials Engineering Faculty Publications and Presentations

Effects of zinc-coated steel type and steel surface sandblasting pretreatment in the solid-liquid compound casting of layered type steel/aluminum bimetals were investigated. The Zn coating behavior and its effects on interfacial microstructure evolution and fracture mechanism were also discussed. The aluminum fluidity in thin plate type flow channels formed by the steel insert and the mold wall primarily depended on the insert surface roughness and secondarily on the wettability. As-galvanized (GI) steel/aluminum bimetal joints showed the bonding strength of 20 MPa and more, while galvannealed (GA) steels showed poor bonding. The interfacial bonding zone consisted of most Al13Fe4, Al8Fe2Si, Al4.5FeSi …

To Burn-In, Or Not To Burn-In: That’S The Question, Ephraim Suhir

Mechanical and Materials Engineering Faculty Publications and Presentations

In this paper it is shown that the bathtub-curve (BTC) based time-derivative of the failure rate at the initial moment of time can be considered as a suitable criterion of whether burn-in testing (BIT) should or does not have to be conducted. It is also shown that the above criterion is, in effect, the variance of the random statistical failure rate (SFR) of the mass-produced components that the product manufacturer received from numerous vendors, whose commitments to reliability were unknown, and their random SFR might vary therefore in a very wide range, from zero to infinity. A formula for the …

Parallelized Particle Swarm Optimization To Estimate The Heat Transfer Coefficients Of Palm Oil, Canola Oil, Conventional, And Accelerated Petroleum Oil Quenchants, Zoltán Fried, Imre Felde, Rosa L. Simencio Otero, Jônatas M. Viscaino, George E. Totten, Lauralice Canale

Mechanical and Materials Engineering Faculty Publications and Presentations

An inverse solver for the estimation of the temporal-spatial heat transfer coefficients (HTC), without using prior information of the thermal boundary conditions, was used for immersion quenching into palm oil, canola oil, and two commercial petroleum oil quenchants. The particle swarm optimization (PSO) method was used on near-surface temperature-time cooling curve data obtained with the so-called Tensi multithermocouple, and a 12.5 by 45 mm Inconel 600 probe. The fitness function to be minimized by a PSO approach is defined by the deviation of the measured and calculated cooling curves. The PSO algorithm was parallelized and implemented on a graphics accelerator …

Monitored Indoor Environmental Quality Of A Mass Timber Office Building: A Case Study, Jason Stenson, Suzanne L. Ishaque, Aurélie Laguerre, Andrew Loia, Georgia Maccrone, Ignace Mugabo, Dale Northcutt, Mariapaola Riggio, Andre Barbosa, Elliott T. Gall, Kevin Van Den Wymelenberg

Mechanical and Materials Engineering Faculty Publications and Presentations

A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to …

Simulation To Fabrication—Understanding The Effect Of Niaucu Alloy Catalysts For Controlled Growth Of Graphene At Reduced Temperature, Huahan Zhan, Bin Jiang, Otto Zietz, Samuel Olson, Jun Jiao

Mechanical and Materials Engineering Faculty Publications and Presentations

It is a significant challenge to grow large-scale, high quality, monolayer graphene at low temperature for the applications in industry, especially for the complementary metal oxide semiconductor fabrication process. To overcome this difficulty, we simulated the decomposition of acetylene (C2H2) on (100) surfaces of primarily nickel (Ni) catalysts with small mol fractions of gold (Au) and copper (Cu), using a 4 × 4 × 4 periodic supercell model. Based on the calculation of the reaction energies to decompose the C-H or C≡C bonds on different catalyst surfaces, a differential energy is proposed to clearly scale the decomposition difficulties such that …

Plasma-Enhanced Chemical Vapor Deposition Of Acetylene On Codeposited Bimetal Catalysts Increasing Graphene Sheet Continuity Under Low-Temperature Growth Conditions, Joshua Tracy, Otto Zietz, Samuel Olson, Jun Jiao

Mechanical and Materials Engineering Faculty Publications and Presentations

Here, we report a novel method for low-temperature synthesis of monolayer graphene at 450 °C on a polycrystalline bimetal Ni-Au catalyst. In this study, low-temperature chemical vapor deposition synthesis of graphene was performed at 450 °C on codeposited Ni-Au which shows successful monolayer graphene formation without an extra annealing process. The experimental results suggest that electron beam codeposition of bimetal catalyst is the key procedure that enables the elimination of the pre-growth high-temperature annealing of the catalyst prior to graphene synthesis, an indispensable process, used in previous reports. The formation was further improved by plasma-assisted growth in which the inductively …