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Articles 1 - 18 of 18
Full-Text Articles in Engineering
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Theses and Dissertations
Ultra high temperature ceramics (UHTCs) are leading candidates for aerospace structural applications in high temperature environments, including the leading edges of hypersonic aircraft and thermal protection systems for atmospheric re-entry vehicles. Before UHTCs can be used in such applications, their structural integrity and environmental durability must be assured, which requires a thorough understanding and characterization of their creep and oxidation behavior at relevant service temperatures.
Investigation Of Electrolyte Wetting In Lithium Ion Batteries: Effects Of Electrode Pore Structures And Solution, Yangping Sheng
Investigation Of Electrolyte Wetting In Lithium Ion Batteries: Effects Of Electrode Pore Structures And Solution, Yangping Sheng
Theses and Dissertations
Beside natural source energy carriers such as petroleum, coal and natural gas, the lithium ion battery is a promising man-made energy carrier for the future. This is a similar process evolved from horse-powered era to engine driven age. There are still a lot of challenges ahead like low energy density, low rate performance, aging problems, high cost and safety etc.
In lithium ion batteries, investigation about manufacturing process is as important as the development of material. The manufacturing of lithium ion battery, including production process (slurry making, coating, drying etc.), and post-production (slitting, calendering etc.) is also complicated and critical …
Finite Element Analysis (Fea) Study Of The Thermal Stress Concentrations In Planar-Type Sodium Sulfur (Nas) Secondary Batteries, Jeffrey P. Colker
Finite Element Analysis (Fea) Study Of The Thermal Stress Concentrations In Planar-Type Sodium Sulfur (Nas) Secondary Batteries, Jeffrey P. Colker
Theses and Dissertations
The importance of a reliable and safe way to store energy, and allow for on-demand usage, has led to much research in the field of secondary battery development. The thesis herein explores a technology that has shown promising results when implemented in large-scale energy grid applications. Though the technology has proven viable in both load-leveling on existing grids as well as serving to legitimize renewable energy sources, the development of such advanced battery systems is not without challenge. Sodium-sulfur (NaS) secondary cells have shown promising results when implemented in the aforementioned energy storage applications. One of the main drawbacks to …
Environmental Degradation Of Nickel-Based Superalloys Due To Gypsiferous Desert Dusts, Matthew B. Krisak
Environmental Degradation Of Nickel-Based Superalloys Due To Gypsiferous Desert Dusts, Matthew B. Krisak
Theses and Dissertations
More than twenty-five years of continuous operation in the dusty environments of Southwest Asia have shown that degradation of gas turbine engine components due to particle ingestion is a serious threat to operations. In particular, the continued push for higher engine operating temperatures has brought a new emphasis to the damage mechanisms (for example CMAS glass formation and hot corrosion) caused by ingested particles forming molten deposits on engine components. Despite decades of research little progress has been made to mitigate the effects of CMAS and hot corrosion degradation to engine components. This research focused on hot corrosion specifically. A …
Characterization Of Point Defects In Lithium Aluminate (Lialo2) Single Crystals, Maurio S. Holston
Characterization Of Point Defects In Lithium Aluminate (Lialo2) Single Crystals, Maurio S. Holston
Theses and Dissertations
Lithium aluminate (LiAlO2) is an insulating wide-band gap material currently under development for tritium breeding and radiation detection and dosimetry applications. Point defects are imperfections in a crystal lattice localized over a few atomic lengths that can alter the electrical, mechanical, or optical properties of materials. An understanding of point defect behavior is a necessary precursor for optimizing lithium aluminate for nuclear applications. This dissertation has identified and characterized the major point defects created and induced through x-ray and neutron radiation using electron paramagnetic resonance and fluorescence spectroscopy, thermoluminescence, and optical absorption. This dissertation explains for the first …
Corrosion Fatigue Crack Growth Behavior At Notched Hole In 7075-T6 Under Biaxial And Uniaxial Fatigue With Different Phases, Ali Khawagi
Theses and Dissertations
This research investigates fatigue crack propagation behavior in both air and saltwater (3.5% NaCl) environments from pre-cracked notched circular hole in a 7075-T6 cruciform specimen. With stress ratio of 0.5, biaxility stress ratio of unity, and frequency of applied load of 10 Hz, the crack growth behavior was investigated under in-plane biaxial tension-tension fatigue with 45⁰, 90⁰ and 180⁰ phase difference conditions and then compared to previous fatigue tests with no phase difference to study the effect of changing the phase differences between the applied loads on the crack growth rate. Finite Element Analysis (FEA) was used to calculate cyclic …
The Optimization Of Concrete Mixtures For Use In Highway Applications, Mohamadreza Moini
The Optimization Of Concrete Mixtures For Use In Highway Applications, Mohamadreza Moini
Theses and Dissertations
Portland cement concrete is most used commodity in the world after water. Major part of civil and transportation infrastructure including bridges, roadway pavements, dams, and buildings is made of concrete. In addition to this, concrete durability is often of major concerns. In 2013 American Society of Civil Engineers (ASCE) estimated that an annual investment of $170 billion on roads and $20.5 billion for bridges is needed on an annual basis to substantially improve the condition of infrastructure. Same article reports that one-third of America’s major roads are in poor or mediocre condition [1]. However, portland cement production is recognized with …
Thermodynamic And Kinetic Simulation Of Transient Liquid-Phase Bonding, Brad Allen Lindner
Thermodynamic And Kinetic Simulation Of Transient Liquid-Phase Bonding, Brad Allen Lindner
Theses and Dissertations
ABSTRACT
THERMODYNAMIC AND KINETIC SIMULATION OF TRANSIENT LIQUID-PHASE BONDING
by
Brad Lindner
The University of Wisconsin-Milwaukee, 2015
Under the Supervision of Professor Benjamin C. Church
The use of numeric computational methods for the simulation of materials systems is becoming more prevalent and an understanding of these tools may soon be a necessity for Materials Engineers and Scientists. The applicability of numerical simulation methods to transient liquid-phase (TLP) bonding is evaluated using a type 316L/MBF-51 material system. The comparisons involve the calculation of bulk diffusivities, tracking of interface positions during dissolution, widening, and isothermal solidification stages, as well as comparison of …
Tin Nanoparticles Encapsulated In Hollow Tio2 Spheres As High Performance Anode Materials For Li-Ion Batteries, Xiang Pan
Theses and Dissertations
Tin, an anode material with a high capacity for lithium-ion batteries, has poor cyclic performance because of the high volume expansion upon lithiation. Based on a literature review of the applications of lithium-ion batteries and current research progress of the tin-based anode materials for lithium-ion batteries, we developed a method to synthesize hollow TiO2 spheres with tin nanoparticles anchored on the inner surface of the TiO2 shell. Such a unique tin/TiO2 composite alleviates the volume change of tin–based anode materials in charge-discharge processes. SnCl2·2H2O (Tin (II) chloride dihydrate) and titanium (IV) isopropoxide (TIPT) were used as the Sn source and …
Experimental Evaluation Of The Effect Of Coal Combustion Products On Constructability, Damage And Aging Resistance Of Asphalt Mastics, Emil Garibaldy Bautista
Experimental Evaluation Of The Effect Of Coal Combustion Products On Constructability, Damage And Aging Resistance Of Asphalt Mastics, Emil Garibaldy Bautista
Theses and Dissertations
Developing a cost-efficient and long-term road infrastructure requires innovative approaches that are both green and environmentally sustainable. Today, building a sustainable, long-lasting, and efficient road infrastructure with little or no repairs is a challenging task and highly innovative technological breakthroughs are urgently needed. For many years fly ash has been effectively used as a partial replacement of portland cement in the production of different types of concrete, as well as in embankments and soil stabilization. On the other hand, the use of Coal Combustion Products (CCPs), including fly ash, as a mineral filler in asphalt pavements has been very limited. …
Novel Two-Dimensional Nanomaterials And Their Gas Sensing Properties, Haihui Pu
Novel Two-Dimensional Nanomaterials And Their Gas Sensing Properties, Haihui Pu
Theses and Dissertations
Graphene, an atomic thin two-dimensional (2D) material with C atoms arranged in a honeycomb lattice, has sparked an unprecedented research interest across various scientific communities since its initial mechanical isolation in 2004. The linear energy dispersion with respect to the momentum within 1 eV around the Fermi level at the high symmetric K (Dirac) points in the Brillouin zone renders graphene a wonder material for scientists. However, graphene’s semimetallic nature significantly limits its high-end applications, e.g., in digital logic circuits. Therefore, continued efforts in opening the band gap for graphene and in searching for novel 2D semiconducting materials are rewarding. …
A Study On The Synthesis - Structure - Property - Performance Relationship Of Bulk Functionalized Polyurethane Foams For Water Filtration Applications, Subhashini Gunashekar
A Study On The Synthesis - Structure - Property - Performance Relationship Of Bulk Functionalized Polyurethane Foams For Water Filtration Applications, Subhashini Gunashekar
Theses and Dissertations
Polymers, macromolecules made of repeat units, are one of the major building blocks of life. They exist naturally in the form of DNA, proteins, sugars, cellulose, natural rubber etc. However, it was only in the mid twentieth century man began to understand its true nature and developed a new class of materials called ‘Plastics’. In recent years, the concept of a truly tailor made polymer has become a reality as a result of better understanding of the polymer structure-property relationships, newer polymerization techniques and due to the availability of new low cost monomers. Polymers from different elements with any desired …
The Design Of High Performance And Ultra-High Performance Fiber Reinforced Cementitious Composites With Nano Materials, Scott W. Muzenski
The Design Of High Performance And Ultra-High Performance Fiber Reinforced Cementitious Composites With Nano Materials, Scott W. Muzenski
Theses and Dissertations
The use of high performance and ultra-high performance cementitious composites (HPC/UHPC) in critical elements of infrastructure can be a sustainable alternative to conventional concrete. These materials provide superior durability, reducing the need for maintenance and early replacement. The use of special cements and nano-materials improve the strength and durability of HPC/UHPC composites by providing a denser microstructure. The addition of high performance fibers enhances the ductility and restricts the crack size, reducing water penetration in cracked material. In HPC, the addition of superhydrophobic admixtures further reduces water permeability and thus provides superior durability and freeze-thaw resistance by producing a preferred …
Fatigue Behavior Of Im7/Bmi 5250-4 Composite At Room And Elevated Temperatures, James T. Tipton
Fatigue Behavior Of Im7/Bmi 5250-4 Composite At Room And Elevated Temperatures, James T. Tipton
Theses and Dissertations
The tension-tension fatigue and tension-compression fatigue behaviors of the IM7/BMI 5250-4 composite were investigated. The tension-tension fatigue of the composite with 0/90 and ±45 fiber orientations was studied at 23, 170, and 190°C. The tension-compression fatigue of the composite with 0/90 fiber orientation was examined at 23°C. The tensile and compressive properties of the composite were also evaluated at room and elevated temperatures for both 0/90 and ±45 fiber orientations. Elevated temperature had little effect on the tensile properties of the 0/90 fiber orientation, but strongly influenced the ±45 tensile properties as well as the compressive properties of both fiber …
Multi-Platform Arabinoxylan Scaffolds As Potential Wound Dressing Materials, Donald C. Aduba Jr
Multi-Platform Arabinoxylan Scaffolds As Potential Wound Dressing Materials, Donald C. Aduba Jr
Theses and Dissertations
Biopolymers are becoming more attractive as advanced wound dressings because of their naturally derived origin, abundance, low cost and high compatibility with the wound environment. Arabinoxylan (AX) is a class of polysaccharide polymers derived from cereal grains that are primarily used in food products and cosmetic additives. Its application as a wound dressing material has yet to be realized. In this two-pronged project, arabinoxylan ferulate (AXF) was fabricated into electrospun fibers and gel foams to be evaluated as platforms for wound dressing materials. In the first study, AXF was electrospun with varying amounts of gelatin. In the second study, AXF …
Peracetic Acid Sterilization Of Electrospun Polycaprolactone Scaffolds, Suyog Yoganarasimha
Peracetic Acid Sterilization Of Electrospun Polycaprolactone Scaffolds, Suyog Yoganarasimha
Theses and Dissertations
Sterilization of tissue engineered scaffolds is an important regulatory issue and is at the heart of patient safety. With the introduction of new biomaterials and micro/nano structured scaffolds, it is critical that the mode of sterilization preserve these built-in features. Conventional sterilization methods are not optimal for engineered polymeric systems and hence alternate systems need to be identified and validated. PCL is polyester with a low melting point (heat labile), susceptible to hydrolysis and is popular in tissue engineering. Electrospinning generates some nanoscale features within the scaffold, the integrity of which can be affected by sterilization method. Chapter 1 explores …
Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab
Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab
Theses and Dissertations
Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO2 capture.
Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to 1200 …
A Study To Evaluate Non-Uniform Phase Maps In Shape Memory Alloys Using Finite Element Method, Naren Motte
A Study To Evaluate Non-Uniform Phase Maps In Shape Memory Alloys Using Finite Element Method, Naren Motte
Theses and Dissertations
The unique thermo-mechanical behavior of Shape Memory Alloys (SMAs), such as their ability to recover the original shape upon heating or being able to tolerate large deformations without undergoing plastic transformations, makes them a good choice for actuators.
This work studies their application in the aerospace and defense industries where SMA components can serve as release mechanisms for gates of enclosures that have to be deployed remotely. This work provides a novel approach in evaluating the stress and heat induced change of phase in a SMA, in terms of the transformation strain tensor. In particular, the FEA tool
ANSYS has …