Engineering Commons^™

Processing, Properties And Prospects For Melt Infiltrated (Mi) Sicf-Ceramic Composites, Raj Singh

Composites at Lake Louise (CALL 2015)

Ceramic materials exhibit superior mechanical properties at high temperatures. But, their use as structural components is severely limited because of their brittleness. Fiber-reinforced ceramic matrix composites (FRCMC), by incorporating fibers in ceramic matrices, not only exploit their attractive high-temperature strength but also enhance their toughness thereby rendering these attractive for many applications. Some of these applications require an understanding of the interrelationship among processing, fiber-matrix interface and mechanical properties both at room and elevated temperatures.

Processing of FRCMC is typically done by chemical vapor infiltration (CVI), filament winding and hot-pressing, and polymer infiltration and pyrolysis (PIP) approaches. Most of these …

Manipulating Electromagnetic Local Density Of States By Graphene Plasmonics, Yongpin P. Chen, Wei E.I. Sha, Li (Lijun) Jun Jiang, Jun Hu

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic local density of states (ELDOS) counts the number of electromagnetic modes at a spatial point where a particle (atom, molecule, and quantum dot) spontaneously emits electromagnetic waves. ELDOS can be interpreted as a density of vacuum fluctuations of electromagnetic fields. Moreover, ELDOS is essential to control spontaneous decay rate (SDR) of particles; and thus plays a critical role in modern optical and quantum devices. Having a great degree of freedom to tune permittivity, graphene is an emerging building block to manipulate the ELDOS. In this work, we study SDR of a particle near a metallic split-ring resonator, which is …

Use Of Fdm Components For Ion Beam And Vacuum Applications, Eric Miguel Tridas

USF Tampa Graduate Theses and Dissertations

This study focuses on novel approaches to the modeling and construction of devices used in ion beam and vacuum systems. Turbulent computational fluid dynamics simulations were performed to model the air flow into an ion funnel system. The results of these simulations were coupled one-way with electrodynamics simulations of the fields generated by the ion funnel. Using the turbulence kinetic energy (k), a spatially varying estimation of the fluctuating component of the velocity field was calculated. These resulting simulations more accurately predicted the ion transmission through the system. Using fused deposition modeling (FDM) novel construction methods for the ion funnel …

Determining Hydrodynamic Forces In Bursting Bubbles Using Dna Nanotube Mechanics, Rizal F. Hariadi, Erik Winfree, Bernard Yurke

Materials Science and Engineering Faculty Publications and Presentations

Quantifying the mechanical forces produced by fluid flows within the ocean is critical to understanding the ocean’s environmental phenomena. Such forces may have been instrumental in the origin of life by driving a primitive form of self-replication through fragmentation. Among the intense sources of hydrodynamic shear encountered in the ocean are breaking waves and the bursting bubbles produced by such waves. On a microscopic scale, one expects the surface-tension–driven flows produced during bubble rupture to exhibit particularly high velocity gradients due to the small size scales and masses involved. However, little work has examined the strength of shear flow rates …

Quantifying The Information Habits Of High School Students Engaged In Engineering Design, Nathan Mentzer, Michael J. Fosmire

Journal of Pre-College Engineering Education Research (J-PEER)

stract This study measured the information gathering behaviors of high school students who had taken engineering design courses as they solved a design problem. The authors investigated what types of information students accessed, its quality, when it was accessed during the students’ process, and if it impacted their thinking during the activity. Students overwhelmingly relied on internet searching to acquire information, rather than printed materials available to them. The sites they found were generally popular rather than technical, and persuasive (i.e., trying to sell something) rather than informative. The high school students understood the need for information, as they sought …

Effect Of An Engineering Camp On Students’ Perceptions Of Engineering And Technology, Rebekah Hammack, Toni A. Ivey, Juliana Utley, Karen A. High

Journal of Pre-College Engineering Education Research (J-PEER)

Students’ knowledge about a profession influences their future decisions about careers. Research indicates that students tend to hold stereotypical views of engineers, which would hinder engineering as a career choice. The purpose of this study was to measure how participating in a week long engineering summer camp affected middle school students’ (N519) attitudes towards engineering and their conceptions of engineering and technology. Results indicate that participation in the programs had a positive impact on the students’ understandings of what technology is and the work engineers do. Although the results indicate a positive impact on participants, it is not clear which …

Teacher Beliefs About Motivating And Teaching Students To Carry Out Engineering Design Challenges: Some Initial Data, James P. Van Haneghan, Susan A. Pruet, Rhonda Neal-Waltman, Jessica M. Harlan

Journal of Pre-College Engineering Education Research (J-PEER)

The present study examines middle school teachers’ beliefs about seven learning outcomes related to a project that involves developing and examining the effects of a set of engineering design modules constructed for use by middle school math and science teachers. Overall, the teachers involved in the intervention appear to believe they have the instructional skills, professional development, and resources to carry out the modules. Teachers from all of the schools (both intervention and comparison schools) for the most part valued the outcomes as important. Results of the study indicate that, although teachers believe they value and can obtain most of …

Engineered Gag-Based Coatings For Mesenchymal Stem Cells, Johna Temenoff

Composites at Lake Louise (CALL 2015)

The therapeutic potency of delivered mesenchymal stem cells (MSCs) in tissue engineering applications may be improved by priming cells toward a differentiated state prior to implantation. Mimicking native extracellular matrix (ECM) interactions, the electrostatic attraction between negatively-charged glycosaminoglycans (GAGs such as heparin and chondroitin sulfate) and positively-charged proteins may act to locally sequester factors present in the culture media (or secreted by nearby cells) to further enhance stem cell response to soluble factors prior to cell transplantation for musculoskeletal disorders.

In these experiments, we desulfated the GAG heparin and heparin (Hep) and desulfated (Hep-) heparin were biotinylated via HOBT/EDC chemistry. …

Single And Double Heterojunction Nanorods For Optoelectronics, Moonsub Shim

Composites at Lake Louise (CALL 2015)

Understanding charge separation and recombination processes and developing materials that can efficiently direct charge carriers with nanoscale precision are of fundamental importance in advancing next-generation electronics, optoelectronics and energy technologies. As semiconductor heterostructures have enabled today’s electronics and optoelectronics, the introduction of active heterojunctions can impart new and improved capabilities that will facilitate integration of colloidal quantum dots into high performance devices. With anisotropic shapes that can be exploited for assembly, charge carrier manipulation and optical anisotropy, incorporating heterojunctions in colloidal semiconductor nanorods presents a promising direction. Various motifs of epitaxial heterojunctions introduced in nanorods through solution chemistry will be …

Concept And Development Of Solid State Ionic Capacitors, Takaaki Tsurumi, Ryoma Ishikawa, Takuya Hoshina, Hiroaki Takeda, Yukio Sakabe

Composites at Lake Louise (CALL 2015)

Development of a new energy storage device that can replace lithium ion batteries is one of the most important subjects for the future of human. Capacitors have an advantage over batteries with respect to the endurance for charge - discharge recycling. Electric double-layer capacitor (EDLC) has been used for some applications but they are still restricted because of relatively low energy density of EDLC in comparison with lithium ion battery and the leakage of liquid electrolyte from packages. Another issue on capacitors is the limit of capacitance density of multi-layered ceramic capacitors (MLCCs). MLCCs are currently used for many electronic …

Electric Eels: Bizarre Natural Phenomena Or Inspiration For Novel Nanocomposite Energy Storage, Erik Spoerke

Composites at Lake Louise (CALL 2015)

The global rush to develop new high energy density, high power density electrical energy storage has motivated a variety of creative, alternative approaches to new technology development. We have adopted one such creative approach, looking to the electric eel as a model for how to manipulate and store electrical energy. These remarkable organisms are capable of repeatedly generating and discharging 1 Ampere of current at over 600V!

The cellular machinery responsible for electrical energy storage in organisms like the electric eel is quite complex (Figure 1), but the driving force behind these sophisticated processes hinges on the relatively simple concept …

Structural Optimization Of Fiber-Reinforced Composite Dental Bridges, Yung Chen, Alex Fok

Composites at Lake Louise (CALL 2015)

The much improved strength of dental restorative materials has brought more flexibility to the design of dental prosthesis, leading to the concept of minimally invasive dentistry. Fiber-reinforced composite (FRC) systems, for example, which provide excellent tooth-colored appearance, allow the amount of tooth removal to be minimized. Clinically, the ideal indication of FRC restoration is single tooth replacement. Depending on the position of the missing tooth, the periodontal status of the neighboring teeth, and the patient’s occlusal force or any existing parafunctional habits, the following two fixed partial denture (FPD) designs can be prescribed: a 3-unit dental bridge supported by two …

Pgx – Technology: A Versatile Technology For Generating Advanced Biopolymer Materials, Bernhard Seifried

Composites at Lake Louise (CALL 2015)

A novel technology is presented utilizing Pressurized Gas eXpanded (PGX) liquids for processing aqueous solutions or dispersions of high molecular weight biopolymers, such as starch, polysaccharides, gums, pectins or cellulose nanocrystals into open-porous morphologies, consisting of nano-scale particles and pores. The highly tune-able PGX process can generate exfoliated nano-composites and highly porous morphologies ranging from sub-micron particles (50nm) to micron-sized granules (2mm), as well as micro- and nanofibrils, granules, fine powders and aerogels with porosities of >99% and specific surface areas exceeding 300 m²/gram. The technology is based on a spray drying method, operating at mild temperatures (40°C) …

Well-Ordered Nanohybrids And Nanoporous Materials From Block Copolymer Templates, Rong Ho

Composites at Lake Louise (CALL 2015)

The design of nanostructured materials and their corresponding morphologies has attracted intense attention. Although many technologies have been explored to fabricate nanostructured materials, templated synthesis is one of the most important approaches to fabricate nanostructured materials with precisely controlled structures and morphologies from their constituent components. Here, we aim to use the self-assembly of block copolymers as an emerging and powerful tool to fabricate well-defined nanomaterials with precise control over the structural dimensions and shape, as well as over the composition and corresponding spatial arrangement. The fabrication of well-ordered nanoporous polymers from the self-assembly of degradable block copolymers, in particular …

Thermosetting Polymers And Composites From Agricultural Oils, Michael Kessler, Richard Larock

Composites at Lake Louise (CALL 2015)

Renewable, bio-based thermosetting copolymer resins, ranging from tough and ductile rubbers to hard and glassy plastics to durable waterborne latex coatings, have been prepared by the polymerization of soybean, corn and linseed oils with various co-monomers. The development of these resin formulations with the right combination of processing viscosity, cure kinetics, and ultimate thermal mechanical properties for various manufacturing processes will be discussed. As expected, the thermal and mechanical properties, as well as the long term environmental durability of the material, are shown to be highly dependent on vegetable-oil composition, processing conditions, and co-monomer chemistry. These new bioplastic composites are …

Rare Earths, Rare-Earth Oxides, And The Ocides’ Unique Character: Application For Environmental Catalysts, Nobuhito Imanaka

Composites at Lake Louise (CALL 2015)

The rare earths series will be comprehensively introduced. The difference among lanthanide, lanthanoid, and rare earths will be also clearly defined. After these lectures, the unique characteristics of rare-earth oxides will be addressed. As one of promising applications of the rare earth oxides, the oxides’ unique character of oxide anion migration in the solids will be also introduced and also for the application as the environmental catalysts.

Here, we focused on C-type cubic Gd₂O₃, and Y₂O₃ which has relatively strong basicity among rare earth elements, as a fundamental oxide to develop a novel …

Nanostructured Metal-Ceramic Composites By Internal Reduction, Ivar Reimanis, Amy Morrissey

Composites at Lake Louise (CALL 2015)

The nucleation and growth of metallic particles within metal-doped oxides exposed to reducing conditions is relevant to the processing of materials for catalysts, fuel cells, and structural applications. Here, the precipitation of metallic nickel during the internal reduction of nickel-doped yttria stabilized zirconia (YSZ) is studied with electron microscopy and SQUID magnetometry. It is shown that the microstructure evolution proceeds in three distinct stages, each with its own kinetics description, dependent on the porosity and grain size. The transitions between stages depend on concentration gradients and electrostatic potentials that act upon the relevant transporting species, namely oxygen vacancies, electrons, nickel …

Stimulus-Responsive And Conductive Composites For Remote Sensing Applications, Anastasia Elias, Preetam Anbukarasu, Dominic Sauvageau

Composites at Lake Louise (CALL 2015)

Inexpensive and portable sensors are increasingly democratizing data collection and data analysis on both large and small scales. Materials which are both conducting and responsive (able to undergo a change in property in response to a desired stimulus) could form the basis for a variety of sensors. In our work, we are developing these materials for use in radio frequency identification (RFID) tags in which the conducting and responsive material is integrated directly into the antenna of the tag. A change in the dielectric properties of the antenna leads to a measurable change in the remotely-readable properties of the device, …

Magneto-Ionic Control Of Interfacial Magnetism, Geoffrey Beach

Composites at Lake Louise (CALL 2015)

Voltage control of magnetism has the potential to substantially reduce power consumption in spintronic memory and logic devices, while offering new functionalities through field-effect operation [1-4]. Magneto-electric coupling has most often been achieved using complex oxides such as ferroelectrics, piezoelectrics, or multiferroic materials. Here I describe a new approach to voltage control of magnetism based on solid-state electrochemical switching of the interfacial oxidation state [2-4] in thin metallic ferromagnets. In ultrathin ferromagnet/oxide bilayers, strong perpendicular magnetic anisotropy (PMA) often arises from arises from interfacial hybridization between the ferromagnetic metal and oxygen ions. By using a solid-state ionic conductor with high …

Use Of Capillary Flow To Create Flexible And Embedded Electronics, Lorraine Francis, Ankit Mahajan, Robert Lade, Chris Macosko, Daniel Frisbie

Composites at Lake Louise (CALL 2015)

Continuous printing processes are attractive for manufacturing electronic devices on flexible substrates and embedding electronically functional materials into polymers. In this presentation, a new method to create flexible electronics based on embedded conductive networks is presented. The route involves creating the electronic architecture in a curable polymer layer on a flexible substrate and then using capillary flow to create the conductive network. In this presentation, the method will be discussed with an emphasis on the role of processing. A key process step is liquid ink flow in channels. Liquid flow in open capillary channels depends on the channel geometry and …

Self-Assembly Directs Enamel Formation And Regeneration, Malcolm Snead

Composites at Lake Louise (CALL 2015)

Enamel is a unique bioceramic tissue covering our teeth, which by improving feeding and nutrition fueled an explosion in vertebrate evolution. Enamel is also the tissue affected by the most prevalent infectious disease of humankind, caries. While enamel is the hardest tissue in the vertebrate body it develops as a soft extracellular protein matrix precursor synthesized by ameloblast cells that is composed mainly of the proteins amelogenin and ameloblastin. Amelogenins are small-, hydrophobic-, inherently disordered proteins that self-assembly to form nanospheres through the interaction of two domains located at opposite molecular ends, whereas, ameloblastin self-assembles through but a single N’-terminal …

Stability Of Oxides/Environmental Barrier Coating Candidate Materials In Hightemperature, High-Velocity Steam, Elizabeth Opila, Robert Golden

Composites at Lake Louise (CALL 2015)

Stability of oxides/Environmental Barrier Coating (EBC) candidate materials in high-temperature, high-velocity steam has been characterized using a steam-jet furnace modeled after Lucato et al [1]. The objective of this work is to quantify stability of oxides for use as coatings on SiC-based composites in turbine engine environments with the long term goal of developing thermochemical life prediction models for EBCs. SiO₂, TiO₂, Y₂O₃, and rare earth silicates were exposed in one atmosphere steam flowing at approximately 170 m/s at temperatures between 1200 and 1400°C for times up to 375 h. Oxide recession, …

Automated Fiber Placement Of Multifunctional Fiber-Reinforced Composites, Christopher Hansen, Konstantine Fetfatsidis, Andrew Burke, Bradford Olson

Composites at Lake Louise (CALL 2015)

Multi-functional composite materials, in which additional functions exist beyond the primary structural function, offer broad scope for system-level performance enhancements. Key functions targeted for composite structures include thermal management, self-healing, and structural health monitoring capabilities. Aerospace and other advanced fiber-reinforced composites applications, which will benefit from these capabilities, are increasingly being manufactured via Automated Fiber Placement (AFP); however, the lack of (1) available material systems suitable for AFP and (2) the lack of processing knowledge regarding their deposition and compaction hinder the automated manufacture of these multifunctional features. Here, we present efforts to create functional pre-preg materials suitable for AFP …

Shape Reconfigurable Liquid Metals, Michael Dickey

Composites at Lake Louise (CALL 2015)

Shape often defines the function of materials. Shape reconfigurable materials are those that can change shape (and thus, function) in response to a stimulus. We have been studying new methods to pattern and control the shape of a micromoldable liquid metal and embed it in functional polymers to create conductors that are soft, self-healing, ultra-stretchable, and shape reconfigurable. The metal is a gallium-based metal alloy that is a low-viscosity liquid at room temperature with low toxicity and negligible volatility. Despite the large surface tension of the metal, it can be molded into non-spherical shapes due to the presence of an …

Printing Living Tissues, Jennifer Lewis

Composites at Lake Louise (CALL 2015)

The ability to pattern biomaterials in planar and three-dimensional forms is of critical importance for several applications, including drug safety screening, tissue engineering and repair. 3D printing enables one to rapidly design and fabricate soft materials in arbitrary patterns without the need for expensive tooling, dies, or lithographic masks. In this talk, our efforts to creating vascularized living tissues via 3D bioprinting will be described. I will present recent advances in the design of cell-laden inks, extracellular matrices and fugitive (vascular) inks for 3D bioprinting of vascularized, heterogeneous cell-laden tissue constructs with as well as ongoing efforts to characterize these …

Icosahedral Phase Strengthened Nanocomposites For Structural Components, Thomas Watson

Composites at Lake Louise (CALL 2015)

The discovery of quasicrystals (QCs) in rapidly solidified Al-Mn alloys has led to a fundamental change in the way that we view the structural spectrum from the amorphous to the crystalline state. This also opened up the possibility of a new class of aluminum-based alloys, because the lack of long-range order in QCs precludes the operation of the usual plastic deformation mechanisms. While a significant amount of work has been done in this area with regards to understanding QCs at the atomic level, very little work has been performed on large-scale materials because the desired microstructures tend to require high …

Polymer Melts Inside Nanoscale Cylindrical Pores: Chain Conformations, Polymer Diffusion And Local Dynamics, Karen Winey

Composites at Lake Louise (CALL 2015)

Polymers in composites and inside porous media are frequently confined to spaces that are comparable to or even smaller than their mean end-to-end distances in the unconfined bulk state. Understanding the impact of nanoscale confinement on both polymer structure and dynamics is critical for a variety of applications including hydraulic fracturing fluids, porous inorganic thin films in the electronics industry, and composites. To date, our work focuses on polymer melts under nanoscale cylindrical confinement. The polymer center-of-mass diffusion into cylindrical pores in anodized aluminum oxide membranes (diameters 18 – 80 nm) was measured using elastic recoil detection. This ion beam …

Dispersion Of Powders In Complex Systems, James Adair

Composites at Lake Louise (CALL 2015)

This talk will discuss our colloidal and interfacial as well as materials chemistry approaches for manipulating and dispersing complex material systems. The talk focuses mostly on aqueous dispersion schemes, but the physical chemistry and utility of the ethanol-water system in preparing colloidal suspensions for diagnostic and drug delivery systems for human healthcare will also be presented. Complex material systems covered can include the following topics: fine ceramic multi-component powder dispersion; managing aqueous dispersion with thermodynamically unstable materials via interfacial passivation strategies; and dispersion of nanoscale particulates in simple and complex physiological environments. Many ceramic and metal systems in suspension are …

Cure Kinetics And Interfacial Phenomena In Polymer Matrix Composites, John Kieffer, Michael Aldridge, Katherine Sebeck, Eleanor Coyle

Composites at Lake Louise (CALL 2015)

Polymer matrix composites with textile reinforcement are used in a wide range of aerospace and industrial applications. Continuum mechanical predictions of the composite behaviors have been inaccurate, possibly because of the lack of information with regard to polymer materials properties, especially near the interfaces with the reinforcing fibers. Concurrent micro-Brillouin and Raman light scattering provides sufficiently high spatial resolution to probe the mechanical properties and chemical composition of the interphase regions of the matrix, without interfering with the thermo-mechanical equilibrium of the material. Using this technique, we mapped the elastic properties of epoxy resin in between and within the fiber …

Additive Manufacturing Of Bulk Refractory Fiber Within The Ta-Hf-C System For Ultra High-Temperature Reinforced Composite Materials, James Maxwell, Ryan Hooper, Nicholas Webb, Jimmy Allen

Composites at Lake Louise (CALL 2015)

This work discusses the production of ultra-high temperature material (UHTM) fibers that can be used to reinforce composite materials in extreme environments. Carbon-fiber-based, carbon-matrix composites are commonly used for many UHTM applications; however within an oxygen containing atmosphere, C-C composites are limited by oxidation well-below their ultimate sublimation temperatures. Hence, research is being carried out to create alternative materials, with very high melting points, but that have greater oxidation resistance. SiC-fiber reinforced composites offer one alternative, but are limited to temperatures below 1870K. Of the 12 binary compounds that have melting points above 3270K, Hafnium Carbide (4170K) and tantalum carbide …