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Experiments And Simulation For 6061-T6 Aluminum Alloy Resistance Spot Welded Lap Joints, Radu Stefanel Florea

Theses and Dissertations

This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded …

Manufacturing Processes In An All-Aluminum Airframe, Stewart Mcdougall

Aerospace Engineering

One often overlooked aspect to building an aircraft is the manufacturing process used to put it into production. This may be a major contributor to acquisition cost and requires a large amount of money to implement. Once all the tooling has been purchased, one of the greatest costs is labor. The experience of building an all-aluminum aircraft shows that the production process is one which may be done in many different ways. Minimizing the assembly time is important for aircraft manufacturers and one of the best ways to do that is on the assembly line itself. Specific practices in the …

The Synthesis And Characterization Of Novel Group 13 Nanostructured Building Block Heterogeneous Silicate Catalysts, Joshua G. Abbott

Doctoral Dissertations

A building block approach and sequential addition methodology were utilized to prepare heterogeneous silicate catalysts containing atomically dispersed group 13 metal (B, Al, Ga) centers. The octa(trimethyltin) silsequioxane, Si8[sub]O12[sub](OSnMe3[sub])8[sub], was used as the building block for the synthesis of these materials. Reaction of the building block with a variety of group 13 metal chlorides led to the formation of cross-linked matrices. All prepared materials were characterized by gravimetric analysis, gas absorption, IR, and NMR. In addition, aluminum and boron samples where characterized by 27[sup]Al and 11[sup]B solid state NMR, and gallium samples were studied using x-ray absorption techniques.

Studies found …

Corrosion Assessment Of Cast Aluminum Parts In Ethanol Fuel Blends, P. Wirot, J. Troset, W. Khonraeng, S. Mahabunphachai, E. Viyanit

Journal of Metals, Materials and Minerals

Nowadays, the use of ethanol fuel blends in automobiles has become more and more worldwide since the ethanol mixture would enhance the performance of the engine and fuel economy ($/mile), while reducing the hazardous exhaust released to the environment. However, the use of ethanol fuel blends may induce some material compatibility issues on some automotive parts that were not designed to be used in contact with ethanol. In other words, the humidity in the ethanol would cause corrosion problem on these parts. The goal of this study is to assess the corrosion value of two cast aluminum parts in a …

Global Estimates Of Mineral Dust Aerosol Iron And Aluminum Solubility That Account For Particle Size Using Diffusion-Controlled And Surface-Area-Controlled Approximations, Qin Han, Charles S. Zender, J. Keith Moore, Clifton S. Buck, Ying Chen, Anne Johansen, Christopher I. Measures

All Faculty Scholarship for the College of the Sciences

Mineral aerosol deposition is recognized as the dominant source of iron to the open ocean and the solubility of iron in the dust aerosol is highly variable, with measurements ranging from 0.01–80%. Global models have difficulty capturing the observed variations in solubility, and have ignored the solubility dependence on aerosol size. We introduce two idealized physical models to estimate the size dependence of mineral aerosol solubility: a diffusion‐controlled model and a surface‐area‐controlled model. These models produce differing time‐ and space‐varying solubility maps for aerosol Fe and Al given the dust age at deposition, size‐resolved dust entrainment fields, and the aerosol …

An Exploratory Investigation Into How Cold Working Can Affect The Acoustic Performance Of Thin Aluminum Foil In A Ribbon Microphone, Alexander (Alex) Stanley

Materials Engineering

Ribbons of 4 μm thin 99.1% pure aluminum foil were cut and corrugated to replace the stock ribbon in an Apex 205 ribbon microphone. Prior to corrugation, half of the ribbons were sandwiched between two KimWipes and two pieces of cardstock then hammered to impart strain hardening. Each ribbon was placed into the microphone capsule and the frequency response of each ribbon was measured. A 10 second sine sweep from 20-20,000 Hz was played through a KRK Rokit 5 speaker and recorded through a ribbon microphone placed 6 inches away from the speaker cone. The signal generated by the ribbon …

Characterization Of Positive Macrosegregation At The Subsurface Of Direct-Chill Cast 7050 Aluminum Forging Billets, Aaron Youril

Materials Engineering

Segregation of alloying elements during casting of forging billets may persist to the final forged component leading to unacceptable surface appearance. Determination of the elements or compounds that segregate is the essential first step to solving this problem. Differential Scanning Calorimetry (DSC) was used to determine a composition profile of the macrosegregation occurring at the subsurface of an as-cast 7050 aluminum alloy billet. Data collection was carried out by separating 10 to 20 mg samples from the outer centimeter along the radius of the billet, as well as samples from the bulk interior of the billet for comparison with the …

Review Of Corrosion Aspects Of Compression Ignition Engine Parts Using Biodiesel Blends, B. Singh, John Korstad, Y. C. Sharma

College of Science and Engineering Faculty Research and Scholarship

This paper reviews the effects of corrosion on the engine parts that come in contact with a newly developed biodiesel fuel and its petrodiesel blend. Copper, aluminum, copper alloys (bronze), and elastomers caused significant levels of corrosiveness in biodiesel and biodiesel blend as opposed to low corrosion with petrodiesel. Specimens of stainless steel showed significant resistance to corrosion in biodiesel samples as compared to copper, aluminum, and copper alloys, but the level of corrosion was still higher than that in petrodiesel. Common methods adopted for measurement of corrosion include weight loss through static emersion tests, and electrochemical techniques by electrochemical …

Resonance Frequencies Of A Spherical Aluminum Shell Subject To Static Internal Pressure, Andrew A. Piacsek, Sami Abdul-Wahid, Robert Taylor

All Faculty Scholarship for the College of the Sciences

Measurements of the vibrational response of a spherical aluminum shell subject to changes in the interior pressure clearly demonstrate that resonance frequencies shift higher as the pressure is increased. The frequency shift appears to be smaller for longitudinal modes than for bending wave modes. The magnitude of frequency shift is comparable to analytical predictions made for thin cylindrical shells. Changes in the amplitudes of resonance peaks are also observed. A possible application of this result is a method for noninvasively monitoring pressure changes inside sealed containers, including intracranial pressure in humans.

Synthesis And High-Pressure Structural Studies Of Aux2 (X= Al, Ga, In) Compounds, Jason Lee Baker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Three intermetallic compounds, AuX₂ (X = Al, Ga, In), were synthesized by arc-melting proper stoichiometric ratios of high purity Au, Al, Ga, and In. They were found to be single-phase in the CaF₂ type Fm3m crystalline structure. Interest in these particular intermetallic materials is due to intriguing pressure-induced behavior such as electronic topological transitions (ETTs), and structural phase transitions as well as their use in a variety of practical applications such as a solar spectral absorber and in electronic circuitry. In this study, the high-pressure structure of these materials was studied using high resolution synchrotron x-ray diffraction (XRD) …

Degradation Of Automotive Materials In Palm Biodiesel

A.S. Md Abdul Haseeb

As compared to petroleum diesel, biodiesel is more corrosive for automotive materials. Studies on the characterization of corrosion products of fuel exposed automotive materials are scarce. Automotive fuel system and engine components are made from different ferrous and non-ferrous materials. The present study aims to investigate the corrosion products of different types of automotive materials such as copper, brass, aluminum and cast iron upon exposure to diesel and palm biodiesel. Changes in fuel properties due to exposure of different materials were also examined. Degradation of metal surface was characterized by digital camera, SEM/EDS and X-ray diffraction (XRD). Fuel properties were …

Aluminum In Food – The Nature And Contribution Of Food Additives, Robert A. Yokel

Pharmaceutical Sciences Faculty Publications

No abstract provided.

Strength And Ductility Of Bulk Nanostructured Aluminum Processed By Mechanical Milling, Nesma Tarik Mohamed Aboulkhair

Theses and Dissertations

Aluminum's many exceptional properties promote it to be as a strong candidate for several applications in the aerospace, automotive, building and packaging industries to name a few. As a result, strengthening Aluminum has been the interest of many researchers over the time. The most commonly followed approaches are alloying and thermal treatments. However, recently, refining the internal structure of materials until reaching the nano-scale range to improve their mechanical properties has been fostered. Specifically speaking, research adopting this approach on various metals has yielded promising results. One of the techniques used to produce nanostructured Aluminum powders, which is the one …

An Empirical Method For Correcting The Detector Spectral Response In Energy-Resolved Ct, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Energy-resolving photon-counting detectors have the potential for improved material decomposition compared to dual-kVp approaches. However, material decomposition accuracy is limited by the nonideal spectral response of the detectors. This work proposes an empirical method for correcting the nonideal spectral response, including spectrum-tailing effects. Unlike previous correction methods which relied on synchrotron measurements, the proposed method can be performed on the scanner. The proposed method estimates a spectral-response matrix by performing x-ray projection measurements through a range of known thicknesses of two or more calibration materials. Once estimated, the spectral-response matrix is incorporated into conventional material decomposition algorithms. A simulation study …

The Pharmacokinetics And Toxicology Of Aluminum In The Brain, Robert A. Yokel

Pharmaceutical Sciences Faculty Publications

The chemical forms (species) of aluminum in blood plasma and brain extracellular fluid are considered, as they are the candidates for brain aluminum uptake and efflux. The blood-brain barrier is the primary site of brain aluminum uptake. The mechanism of brain uptake of aluminum transferrin, long thought to be mediated by transferrin-receptor mediated endocytosis, requires further investigation. Brain Al citrate uptake has been attributed to the sodium-independent Lglutamate/ L-cystine exchanger system, system Xc-. Reports have suggested aluminum can compromise blood-brain barrier integrity, however the studies were conducted with aluminum concentrations greatly exceeding those seen in human blood plasma. Aluminum appeared …

A Critical Review On Corrosion Of Compression Ignition (Ci) Engine Parts By Biodiesel And Biodiesel Blends And Its Inhibition, B. Singh, John Korstad, Y. C. Sharma

College of Science and Engineering Faculty Research and Scholarship

This paper reviews the effects of corrosion on the engine parts that come in contact with a newly developed biodiesel fuel and its petrodiesel blend. Copper, aluminum, copper alloys (bronze), and elastomers caused significant levels of corrosiveness in biodiesel and biodiesel blend as opposed to low corrosion with petrodiesel. Specimens of stainless steel showed significant resistance to corrosion in biodiesel samples as compared to copper, aluminum, and copper alloys, but the level of corrosion was still higher than that in petrodiesel. Common methods adopted for measurement of corrosion include weight loss through static emersion tests, and electrochemical techniques by electrochemical …

Die Attach Properties Of Zn-Al-Mg-Ga Based High-Temperature Lead-Free Solder On Cu Lead-Frame

A.S. Md Abdul Haseeb

No abstract provided.

A Reaction Progress Variable Modeling Approach For Non-Ideal Multiphase Explosives, K. P. Ruggirello, P. E. Desjardin, M. R. Baer, M. J. Kaneshige, E. S. Hertel

US Department of Energy Publications

This study concerns the development of a mixture fraction based reaction progress variable formulation for aluminized explosives. Highlights of the formulation include a fully compressible treatment of both the gas and solid phases (both aluminum and alumina), heterogenous and homogenous reactions, and effects of group combustion. Isolated particle simulations are validated against experimental data and DNS and show good agreement of burn times over a range of pressure and oxygen environments. The new models are implemented in the CTH shock physics code using a fractional step approach to allow for efficient computation of particle dynamics. Comparisons are made to experimental …

Identifying Smart Conducting Materials For Wi-Fi Electromagnetic Interference Shielding, Wham Al-Shabib, Daryoush Habibi, Zonghan Xie, Xiaoli Zhao

Research outputs 2012

The objective of this paper is to identify a suitable coating material in order to tune the microwave radiation and produce absorption losses for Wi-Fi devices. It is also desirable to obtain high absorption losses outside the Wi-Fi microwave frequency range of 2.4 GHz. Literature reviews of several types of material are described and compared for the use of the selected material in order to coat a Wi-Fi device for the desired absorption losses for that device. The selected material for the Wi-Fi device is usually a metal material or a combination of metals like Aluminium in polymer matrix with …

Effect Of Al Compounds On Soil Ph And Bioavailability Of Al In Two Acid Soils, Toufiq Iqbal

Turkish Journal of Agriculture and Forestry

Two aluminum compounds, AlCl_3 and Al(OH)_3, were used to determine the effect of Al compounds on pH and bioavailability of Al in 2 acid soils. Both soils were incubated for periods of 3, 10, and 30 days. Al-tolerant (ET8) and Al-sensitive (ES8) wheat seedlings were used as a testing plant to confirm bioavailability of Al^{3+} in soil solution. Both soils were acidified through the addition of Al compounds to detect the maximum Al^{3+} toxicity level of these compounds. The results showed that the AlCl3 compound increased the bioavailability of Al^{3+} in soil solutions. In contrast, AlCl_3 decreased bulk soil pH. …

Rapid And Noncontaminating Sampling System For Trace Elements In Global Ocean Surveys, Gregory A. Cutter, Kenneth W. Bruland

OES Faculty Publications

A system for the rapid and noncontaminating sampling of trace elements with volumes of up to 36 L per depth and including the dissolved and particulate phases has been developed for ocean sections that are a crucial part of programs such as International GEOTRACES. The system uses commercially available components, including an aluminum Seabird Carousel with all titanium pressure housings for electronics and sensors to eliminate zinc sacrificial anodes and holding twenty-four 12 L GO-FLO bottles, and a 7500 m, 14 mm Vectran conducting cable (passing over an A-frame with nonmetallic sheave) spooled onto a traction winch. The GO-FLO bottles …

The Effects Of Informational Prompts And Performance Feedback On Recyclign Behavior, Erin Marie Zandecki

USF Tampa Graduate Theses and Dissertations

Recycling behavior was examined by the implementation of Informational Prompts and Performance Feedback. Prompts containing facts on recycling and waste along with group performance feedback were studied at The Florida Mental Health Institute at The University of South Florida (Tampa campus). Informational Prompts were introduced by placing informational facts about recycling and waste by 26 bins throughout the building. Performance feedback signs were placed by the same bins and included the frequency of recycled material and trash discarded in the recycling bins on a daily basis when the campus was open. The results showed that both interventions increased recycling. Informational …

Study Of Vacancy-Type Defects By Positron Annihilation In Ultrafine-Grained Aluminum Severely Deformed At Room And Cryogenic Temperatures, L H. Su, Cheng Lu, Lizi He, L C. Zhang, P Guagliardo, A K. Tieu, S N. Samarin, J F. Williams, H J. Li

Faculty of Engineering - Papers (Archive)

"Commercial-purity aluminum was processed by equal-channel angular pressing (ECAP) at room temperature (RT-ECAP) and cryogenic temperature (CT-ECAP) with liquid nitrogen cooling between two successive passes.It was found that the RT-ECAPed samples showed equiaxed microstructure after 4 and 8 ECAP passes, while the CT-ECAPed samples displayed slightly elongated microstructure and slightly smaller grain size.Moreover, the CT-ECAPed samples had higher hardness values than the RT-ECAPed samples subjected to the same amount of deformation.Positron annihilation lifetime spectroscopy (PALS) was used to investigate the evolution of vacancy-type defects during the ECAP deformation process.The results showed that three types of defects existed in the ECAPed …

Asymmetric Cryorolling For Fabrication Of Nanostructural Aluminum Sheets, Hailiang Yu, Cheng Lu, K. Tieu, Xianghua Liu, Yong Sun, Qingbo Yu, Charlie Kong

Faculty of Engineering - Papers (Archive)

Nanostructural Al 1050 sheets were produced using a novel method of asymmetric cryorolling under ratios of upper and down rolling velocities (RUDV) of 1.1, 1.2, 1.3, and 1.4. Sheets were rolled to about 0.17 mm from 1.5 mm. Both the strength and ductility of Al 1050 sheets increase with RUDVs. Tensile strength of Al sheets with the RUDV 1.4 is larger 22.3% of that for RUDV 1.1, which is 196 MPa. The TEM observations show the grain size is 360 nm when the RUDV is 1.1, and 211 nm for RUDV 1.4.

Reinforcement With Graphene Nanosheets In Aluminum Matrix Composites, Jingyue Wang, Zhiqiang Li, Genlian Fan, H H Pang, Zhixin Chen, Di Zhang

Faculty of Engineering and Information Sciences - Papers: Part A

Graphene has a high fracture strength of 125 GPa, making it an ideal reinforcement for composite materials. Aluminum composites reinforced with graphene nanosheets (GNSs) were fabricated for the first time through a feasible methodology based on flake powder metallurgy. The tensile strength of 249 MPa was achieved in the Al composite reinforced with only 0.3 wt.% GNSs, which is 62% enhancement over the unreinforced Al matrix. The relevant strengthening mechanisms involved in the GNS/Al composites were discussed along with experimental procedure.

Controls On Dissolved Cobalt In Surface Waters Of The Sargasso Sea: Comparisons With Iron And Aluminum, R. U. Shelley, Peter N. Sedwick, T. S. Bibby, P. Cabedo-Sanz, T. M. Church, R. J. Johnson, A. I. Macey, C. M. Marsay, E. R. Sholkovitz, S. J. Ussher, P. J. Worsfold, M. C. Lohan

OES Faculty Publications

Dissolved cobalt (dCo), iron (dFe) and aluminum (dAl) were determined in water column samples along a meridional transect (∼31°N to 24°N) south of Bermuda in June 2008. A general north-to-south increase in surface concentrations of dFe (0.3-1.6 nM) and dAl (14-42 nM) was observed, suggesting that aerosol deposition is a significant source of dFe and dAl, whereas no clear trend was observed. for near-surface dCo concentrations. Shipboard aerosol samples indicate fractional solubility values of 8-100% for aerosol Co, which are significantly higher than corresponding estimates of the solubility of aerosol Fe (0.44-45%). Hydrographic observations and analysis of time series rain …

A Material System For Reliable Low Voltage Anodic Electrowetting, Mehdi Khodayari, Jose Carballo, Nathan B. Crane

Faculty Publications

Electrowetting on dielectric is demonstrated with a thin spin-coated fluoropolymer over an aluminum electrode. Previous efforts to use thin spin-coated dielectric layers for electrowetting have shown limited success due to defects in the layers. However, when used with a citric acid electrolyte and anodic voltages, repeatable droplet actuation is achieved for 5000 cycles with an actuation of just 10 V. This offers the potential for low voltage electrowetting systems that can be manufactured with a simple low-cost process.