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Full-Text Articles in Engineering

Numerical Simulation Of Laser Induced Elastic Waves In Response To Short And Ultrashort Laser Pulses., Alireza Zarei May 2024

Numerical Simulation Of Laser Induced Elastic Waves In Response To Short And Ultrashort Laser Pulses., Alireza Zarei

All Dissertations

In an era of intensified market competition, the demand for cost-effective, high-quality, high-performance, and reliable products continues to rise. Meeting this demand necessitates the mass production of premium products through the integration of cutting-edge technologies and advanced materials while ensuring their integrity and safety. In this context, Nondestructive Testing (NDT) techniques emerge as indispensable tools for guaranteeing the integrity, reliability, and safety of products across diverse industries.

Various NDT techniques, including ultrasonic testing, computed tomography, thermography, and acoustic emissions, have long served as cornerstones for inspecting materials and structures. Among these, ultrasonic testing stands out as the most prevalent method, …


Mechanics Of Pure Bending And Eccentric Buckling In High-Strain Composite Structures, Jimesh D. Bhagatji, Oleksandr G. Kravchenko, Sharanabasaweshwara Asundi Jan 2024

Mechanics Of Pure Bending And Eccentric Buckling In High-Strain Composite Structures, Jimesh D. Bhagatji, Oleksandr G. Kravchenko, Sharanabasaweshwara Asundi

Mechanical & Aerospace Engineering Faculty Publications

To maximize the capabilities of nano- and micro-class satellites, which are limited by their size, weight, and power, advancements in deployable mechanisms with a high deployable surface area to packaging volume ratio are necessary. Without progress in understanding the mechanics of high-strain materials and structures, the development of compact deployable mechanisms for this class of satellites would be difficult. This paper presents fabrication, experimental testing, and progressive failure modeling to study the deformation of an ultra-thin composite beam. The research study examines the deformation modes of a post-deployed boom under repetitive pure bending loads using a four-point bending setup and …


Advancements And Challenges In Additively Manufactured Functionally Graded Materials: A Comprehensive Review, Suhas Alkunte, Ismail Fidan, Vivekanand Naikwadi, Shamil Gudavasov, Mohammad Alshaikh Ali, Mushfig Mahmudov, Seymur Hasanov, Muralimohan Cheepu Jan 2024

Advancements And Challenges In Additively Manufactured Functionally Graded Materials: A Comprehensive Review, Suhas Alkunte, Ismail Fidan, Vivekanand Naikwadi, Shamil Gudavasov, Mohammad Alshaikh Ali, Mushfig Mahmudov, Seymur Hasanov, Muralimohan Cheepu

Engineering Technology Faculty Publications

This paper thoroughly examines the advancements and challenges in the field of additively manufactured Functionally Graded Materials (FGMs). It delves into conceptual approaches for FGM design, various manufacturing techniques, and the materials employed in their fabrication using additive manufacturing (AM) technologies. This paper explores the applications of FGMs in diverse fields, including structural engineering, automotive, biomedical engineering, soft robotics, electronics, 4D printing, and metamaterials. Critical issues and challenges associated with FGMs are meticulously analyzed, addressing concerns related to production and performance. Moreover, this paper forecasts future trends in FGM development, highlighting potential impacts on diverse industries. The concluding section summarizes …


In Situ High Temperature Fiber-Optic Raman Sensor For Industrial Applications, Bohong Zhang Jan 2024

In Situ High Temperature Fiber-Optic Raman Sensor For Industrial Applications, Bohong Zhang

Doctoral Dissertations

"Continuous casting in steel production uses specially developed oxyfluoride glasses (mold fluxes) to lubricate a mold and control the solidification of the steel in the mold. The composition of the flux impacts properties, including basicity, viscosity, and crystallization rate, all of which affect the stability of the casting process and the quality of the solidified steel. However, mold fluxes interact with steel during the casting process, resulting in flux chemistry changes that must be considered in the flux design. Currently, the chemical composition of mold flux must be determined by extracting flux samples from the mold during casting and then …


Nonlinear Finite Element Model For Functionally Graded Porous Circular/Annular Micro-Plates Under Thermal And Mechanical Load, Enrique Nava Munoz Dec 2023

Nonlinear Finite Element Model For Functionally Graded Porous Circular/Annular Micro-Plates Under Thermal And Mechanical Load, Enrique Nava Munoz

Masters Theses

A nonlinear finite element model for micro circular/annular plates under thermal and mechanical loading is developed using a third order shear deformation theory. In the kinematic assumptions, the change of plate thickness is allowed and no transverse shear strains are considered on the top and bottom surfaces. A power-law distribution is utilized to account for variations of two constituents through the thickness of the plate. Three different types of porosity distributions are considered. The strain gradient effect in micro scale structures is considered using the modified couple stress theory. The dynamic version of the principle of virtual displacements is used …


Boron Nitride Nanotubes: Force Field Parameterization, Epoxy Interactions, And Comparison With Carbon Nanotubes For High-Performance Composite Materials, Swapnil S. Bamane, Michael B. Jakubinek, Krishan Kanhaiya, Behnam Ashrafi, Hendrik Heinz, Gregory Odegard Feb 2023

Boron Nitride Nanotubes: Force Field Parameterization, Epoxy Interactions, And Comparison With Carbon Nanotubes For High-Performance Composite Materials, Swapnil S. Bamane, Michael B. Jakubinek, Krishan Kanhaiya, Behnam Ashrafi, Hendrik Heinz, Gregory Odegard

Michigan Tech Publications

Boron nitride nanotubes (BNNTs) are a very promising reinforcement for future high-performance composites because of their excellent thermo-mechanical properties. To take full advantage of BNNTs in composite materials, it is necessary to have a comprehensive understanding of the wetting characteristics of various high-performance resins. Molecular dynamics (MD) simulations provide an accurate and efficient approach to establish the contact angle values of engineering polymers on reinforcement surfaces, which offers a measure for the interaction between the polymer and reinforcement. In this research, MD simulations and experiments are used to determine the wettability of various epoxy systems on BNNT surfaces. The reactive …


Non-Destructive Infrared Thermographic Curing Analysis Of Polymer Composites, Md Ashiqur Rahman, Javier Becerril, Dipannita Ghosh, Nazmul Islam, Ali Ashraf Feb 2023

Non-Destructive Infrared Thermographic Curing Analysis Of Polymer Composites, Md Ashiqur Rahman, Javier Becerril, Dipannita Ghosh, Nazmul Islam, Ali Ashraf

Mechanical Engineering Faculty Publications and Presentations

Infrared (IR) thermography is a non-contact method of measuring temperature that analyzes the infrared radiation emitted by an object. Properties of polymer composites are heavily influenced by the filler material, filler size, and filler dispersion, and thus thermographic analysis can be a useful tool to determine the curing and filler dispersion. In this study, we investigated the curing mechanisms of polymer composites at the microscale by capturing real-time temperature using an IR Thermal Camera. Silicone polymers with fillers of Graphene, Graphite powder, Graphite flake, and Molybdenum disulfide (MoS2) were subsequently poured into a customized 3D printed mold for …


Biomass Characterization And Insulation Optimization Studies, Hussein Awad Kurdi Saad Nov 2022

Biomass Characterization And Insulation Optimization Studies, Hussein Awad Kurdi Saad

Doctoral Dissertations and Master's Theses

This study indicates how biomass materials can be effectively used as naturally sustainable alternatives to insulation materials. Barley grains and oak leaves, straw, and jute are collected, and crushed into powders/ chopped pieces. The physical characteristics are measured to characterize each powder. The biomass powder reinforced composites are manufactured in varying weight ratios. The density and thermal conductivity of composite materials are measured. The properties of composites compared to those of commercial insulation materials are found to be close to them. Furthermore, genetic algorithms (GA) can be used to achieve multi-objective optimization entailing maximizing insulation (minimizing heat transfer) and simultaneously …


Analysis Guidelines And Functionalities Of The Catia Native Fea Solver For Composite Materials, Mohamed Edrisy Feb 2022

Analysis Guidelines And Functionalities Of The Catia Native Fea Solver For Composite Materials, Mohamed Edrisy

Electronic Theses and Dissertations

The emergence of commercial FEA solvers was a significant breakthrough that boosted the accuracy and complexity of engineering design. While composite materials are special materials, their mechanical properties can be custom made by considering the needs and requirements of the design problem. Given the rapidly expanding global consumption of composite materials, access to FEA solvers capable of assigning these materials is an absolute requirement.The CATIA software is a platform for designing, analyzing, and manufacturing of parts. However, there is no meaningful documentation in the public domain exploring the finite element functionalities of CATIA software for composite materials. Isotropic materials are …


Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian Jan 2022

Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian

Dissertations, Master's Theses and Master's Reports

Composite materials require a multi-scale approach to fully understand its behavior. At the micro level, material behavior analysis is conducted most often using numerical or analytical approaches. These models, however, require validation from experimental data to ensure material predictions are accurate. This study compares a semi-analytical micromechanical analysis tool, MAC/GMC, to experimental results of in-situ microscale transverse compression testing conducted at AFRL facilities. Effective properties, stress-strain curves, stress and strain fields, and damage predictions are compared with experimental outputs. Both generalized method of cells (GMC) and high-fidelity generalized method of cells (HFGMC) theories implemented within MAC/GMC show results that agree …


Data-Driven Damage Initiation Criteria For Carbon Fiber Reinforced Polymer Composites, Alexander Richard Post Nov 2021

Data-Driven Damage Initiation Criteria For Carbon Fiber Reinforced Polymer Composites, Alexander Richard Post

College of Computing and Digital Media Dissertations

Computational progressive failure analysis (PFA) is vital for the design, verification, and validation of carbon fiber reinforced polymer (CFRP) composites. However, the computational cost of PFA is usually high due to the complexity of the model. The damage initiation criterion is one of the essential components of a PFA code to determine the transition of a material’s state from pristine or microscopically damaged to macroscopically damaged. In this thesis, data-driven models are developed to determine the matrix damage initiation based on the Mohr-Coulomb model and Hashin model. For 2D plane stress states, the computational cost for determining damage initiation can …


Impact Behavior Of Laminated Composites Built With Fique Fibers And Epoxy Resin: A Mechanical Analysis Using Impact And Flexural Behavior, Julian Rua, Mario F. Buchely, Sergio Neves Monteiro, Gloria I. Echeverri, Henry A. Colorado Sep 2021

Impact Behavior Of Laminated Composites Built With Fique Fibers And Epoxy Resin: A Mechanical Analysis Using Impact And Flexural Behavior, Julian Rua, Mario F. Buchely, Sergio Neves Monteiro, Gloria I. Echeverri, Henry A. Colorado

Materials Science and Engineering Faculty Research & Creative Works

This research analyzes the behavior of natural fiber reinforced laminated polymer composites (NFRPC) under mechanical solicitations. Samples were fabricated with epoxy resin matrix reinforced with a multilayer natural fique fiber in a bi-directional commercial fabric configuration. Different reinforcement contents without additives were prepared taking in the account the simplicity in processing, fabrication cost, and applications in which this material might be used with high performance standards. Charpy notched impact and 3-point bending test were carried out to evaluate the mechanical behavior and the work of fracture, which was improved significatively with the fibers, showing an increase from 5 to 30 …


Design, Analysis And Experimental Evaluation Of 3d Printed Variable Stiffness Structures, Rossana R. Fernandes Aug 2021

Design, Analysis And Experimental Evaluation Of 3d Printed Variable Stiffness Structures, Rossana R. Fernandes

Doctoral Dissertations and Master's Theses

The rapid progress of additive manufacturing (AM) introduces new opportunities but also new challenges for design and optimization to ensure manufacturability, testability and accurate representation/prediction of the models. The present dissertation builds a bridge between design, optimization, AM, testing and simulation of advanced optimized variable-stiffness structures. The first part offers an insight on the mechanical, viscoelastic and failure characteristics of AM continuous fiber composites. This understanding was used in the second part to investigate the feasibility of different topology and fiber-orientation optimization methods and the manufacturability of the resulting models. The study also assesses the effects of the manufacturing constraints …


Solvent Analysis Of Phenolic Resin Glass Fiber Reinforced Prepreg During Out-Time, Sixin Zhai, Crystal Ipong Jun 2021

Solvent Analysis Of Phenolic Resin Glass Fiber Reinforced Prepreg During Out-Time, Sixin Zhai, Crystal Ipong

Materials Engineering

Phenolic resin glass fiber reinforced prepregs are highly suitable for airplane interior components due to their high fire resistance, high temperature performance, and low-density characteristics. Safran Cabin seeks to improve their storage of the phenolic resin prepreg during their manufacturing process. The issues the company faces are the occasional delamination of prepreg laminas or the loss of tackiness rendering the lamina unfit for use. The area of investigation was determining the weight loss of volatiles during out-time. The term “out-time” consists of the time the prepreg experiences in transit, on the shop floor, and in short-term temperature-controlled storage. Simulated storage …


Exploring The Impact Of Composite Material Fires And Associated Response Protocol On The Material Analysis During An Aircraft Accident Investigation, Flavio A. C. Mendonca, Natalie Zimmermann, Peng Hao Wang, Julius Keller Jan 2021

Exploring The Impact Of Composite Material Fires And Associated Response Protocol On The Material Analysis During An Aircraft Accident Investigation, Flavio A. C. Mendonca, Natalie Zimmermann, Peng Hao Wang, Julius Keller

Publications

Metals, beginning in the 1930s, have been frequently used as the material of choice for aircraft construction (Hallion, 1978; Jakab, 1999). Common metals used in the aviation industry range from alloyed and heat-treated aluminum to titanium, magnesium, and superalloys, the latter used in specialized applications (Hallion, 1978; Mouritz, 2012). Nevertheless, a shift in aircraft construction – specifically in terms of the materials used – began in the 1970s, as composite materials were introduced into commercial aircraft (Mouritz, 2012). Among others, the increased use of composited materials was – and still is – propelled by the ability to manufacture comparative lightweight …


Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer Dec 2020

Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer

Theses and Dissertations

Composite materials are strong, lightweight, and stiff making them desirable in aerospace applications. However, a practical issue arises with composites in that they behave unpredictably in bolted joints, where damage and cracks are often initiated. This research investigated a solution to correcting the problem with composite bolted joints. A novel hybrid composite material was developed, where thin stainless steel foils were placed between and in place of preimpregnated composite plies during the cure cycle to reinforce stress concentrations in bolted joints. This novel composite was compared to control samples experimentally in quasi-static monotonic loading in double shear configuration in 9-ply …


Properties And Performance Of The Basalt-Fiber Reinforced Texture Roof Tiles, Parinya Chakartnarodom, Wichit Prakaypan, Pitcharat Ineure, Nutthita Chuankrerkkul, Edward A. Laitila, Nuntaporn Kongkajun Dec 2020

Properties And Performance Of The Basalt-Fiber Reinforced Texture Roof Tiles, Parinya Chakartnarodom, Wichit Prakaypan, Pitcharat Ineure, Nutthita Chuankrerkkul, Edward A. Laitila, Nuntaporn Kongkajun

Michigan Tech Publications

The mechanical and the physical properties, and the performance of texture roof tiles reinforced with the basalt fibers were observed. The samples of the basalt-fiber reinforced texture roof tiles were produced on the industrial scale by using filter pressing method. After forming, the as-molded samples were air cured and characterized based on ASTM C1185 standard for their mechanical properties and physical properties. In addition, the roof-tile installation test was also performed. The results showed that the samples of the basalt-fiber reinforced texture roof tile (BFRT) could be produced on the industrial scale by using the common setting of the forming …


Modeling Hybrid Composites Using Tsai-Wu And Hashin Failure Criterion, Candice R. Roberts Mar 2020

Modeling Hybrid Composites Using Tsai-Wu And Hashin Failure Criterion, Candice R. Roberts

Theses and Dissertations

Hybrid composites require further study and testing for future use in various fields. This study focuses on simulating a Hybrid Composite using IM7-977-3 laminae with steel foils in Abaqus under bolt loading by using Hashin and Tsai-Wu failure criterion. Initial simulations contain only the IM7-977-3 composite with cohesive layers. Foil samples were then tested for accurate material properties from which the simulations were then updated to include steel foils. The two models show that Tsai-Wu failure criterion, while great for anisotropic material in tension, does not prove accuracy around the hole of the composite material which is in compression. Hashin …


Low Weight Design Of A Pressure-Fed System For A Small Payload Launch Vehicle, Lucero Buendia Jan 2020

Low Weight Design Of A Pressure-Fed System For A Small Payload Launch Vehicle, Lucero Buendia

Open Access Theses & Dissertations

Carbon fiber reinforced polymer (CFRP) composites have become of great interests to aerospace industries because of their low-cost, lightweight and their tailorable mechanical properties. In aerospace structures, for example, heavy metals have been used in cryogenic fuel and oxidizer tanks for over 50 years. However, weight savings can be substantial if materials such as composites are used instead. From Delta IV heavy-lift launch vehicle it is known that cryogenic composite tanks can save approximately up to 30% of weight in fuel and oxidizer tanks. Although there is a wealth of studies in the mechanical behavior of composites at room temperature, …


Seismic Behavior Of Composite Bridge Columns, Mohanad M. Abdulazeez Jan 2020

Seismic Behavior Of Composite Bridge Columns, Mohanad M. Abdulazeez

Doctoral Dissertations

“This study investigates experimentally and numerically the seismic behavior of large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) innovative bridge columns as a sustainable approach to endure and rapidly recover from natural disasters such as earthquakes. The HC-FCS column consisted of a concrete shell sandwiched between an outer fiber-reinforced polymer (GFRP) tube and an inner steel tube to provided continuous confinement for the concrete shell along with the height of the column. The columns have a slender inner steel tube with diameter-to-thickness (Ds/ts) ratios ranged between 85 to 254. Each steel tube was embedded into the footing, while the …


Influence Of Composite Materials Surface Metal Mesh On Helicopter Lightning Stroke Effects, Junling Huang, Jiayu Xie Nov 2019

Influence Of Composite Materials Surface Metal Mesh On Helicopter Lightning Stroke Effects, Junling Huang, Jiayu Xie

Journal of System Simulation

Abstract: The metal wire mesh is usually adopted to prevent the lightning stroke on composite materials. The effects of different materials and different thickness of metal mesh on helicopter lightning electromagnetic effect are compared. According to the method recommended by SAE-ARP5416, a numerical simulation software is used for carrying out the high current injection simulation. The results show that the surface mount metal mesh can effectively reduce the harm of lightning electromagnetic coupling effect; the difference between aluminum and copper on anti-lightning stroke effect is not obvious; when the thickness of aluminum grid is less than 0.15 mm, the …


Composite Materials Based On Twaron And Nano Materials, Omnia Hamdy, Remon A. Mankarious, M. A. Radwan, M. A. Sadek, Hany A. Elazab Nov 2019

Composite Materials Based On Twaron And Nano Materials, Omnia Hamdy, Remon A. Mankarious, M. A. Radwan, M. A. Sadek, Hany A. Elazab

Chemical Engineering

This research aims to participate in producing body shield that can overcome pervious drawbacks using behaviour of shear thickening fluid. Initially, the rheological behaviour of silica-polyethylene glycol shear thickening fluid is examined at different concentrations. Then, ballistic fabric samples are impregnated into silica-polyethylene glycol shear thickening fluid at various concentrations of silica and tested using gas gun simulating real ballistic threat. After that, the impact of rubbery hot water pack filled with around 66.67 wt% starch in water is tested using gas gun. Results showed as the concentration of silica increases, the indentation depth in the impregnated fabric decreases which …


Composite Materials Based On Twaron And Nano Materials, Omnia Hamdy, Remon A. Mankarious, M. A. Radwan, M. A. Sadek, Hany A. Elazab Nov 2019

Composite Materials Based On Twaron And Nano Materials, Omnia Hamdy, Remon A. Mankarious, M. A. Radwan, M. A. Sadek, Hany A. Elazab

Chemical and Biochemical Engineering Faculty Research & Creative Works

This research aims to participate in producing body shield that can overcome pervious drawbacks using behavior of shear thickening fluid. Initially, the rheological behavior of silica-polyethylene glycol shear thickening fluid is examined at different concentrations. Then, ballistic fabric samples are impregnated into silica-polyethylene glycol shear thickening fluid at various concentrations of silica and tested using gas gun simulating real ballistic threat. After that, the impact of rubbery hot water pack filled with around 66.67 wt% starch in water is tested using gas gun. Results showed as the concentration of silica increases, the indentation depth in the impregnated fabric decreases which …


Prototyping A Conductive Polymer Steering Pad For Rail Freight Service, Anthony A. Villarreal, Constantine Tarawneh, Miguel Ontiveros, James Aranda, Robert Jones Jul 2019

Prototyping A Conductive Polymer Steering Pad For Rail Freight Service, Anthony A. Villarreal, Constantine Tarawneh, Miguel Ontiveros, James Aranda, Robert Jones

Mechanical Engineering Faculty Publications and Presentations

The AdapterPlus™ steering pad is a polymer component on a railcar that helps to reduce stresses on the axle as a railcar rounds a curve. One railway application requires a minimum of 240 mA to be passed through the steering pad to the rail, which activates air valves that control automated cargo gates. Currently, two copper studs are inserted into the pad to provide a conductive path. However, after continuous cyclic loading caused by normal service operation, the copper studs deform, wear, and eventually lose contact between the two surfaces rendering the pad nonconductive. One proposed solution to this problem …


Predicting The Mechanical Properties Of Nanocomposites Reinforced With 1-D, 2-D And 3-D Nanomaterials, Scott Edward Muller May 2019

Predicting The Mechanical Properties Of Nanocomposites Reinforced With 1-D, 2-D And 3-D Nanomaterials, Scott Edward Muller

Graduate Theses and Dissertations

Materials with features at the nanoscale can provide unique mechanical properties and increased functionality when included as part of a nanocomposite. This dissertation utilizes computational methods at multiple scales, including molecular dynamics (MD) and density functional theory (DFT), and the coupled atomistic and discrete dislocation multiscale method (CADD), to predict the mechanical properties of nanocomposites possessing nanomaterials that are either 1-D (carbyne chains), 2-D (graphene sheets), or 3-D (Al/amorphous-Si core-shell nanorod).

The MD method is used to model Ni-graphene nanocomposites. The strength of a Ni-graphene nanocomposite is found to improve by increasing the gap between the graphene sheet and a …


Strength Of Reinforced Concrete Elements Strengthened With Carbon Fiber External Reinforcement, B. Sagatov, N. Rakhmanov Apr 2019

Strength Of Reinforced Concrete Elements Strengthened With Carbon Fiber External Reinforcement, B. Sagatov, N. Rakhmanov

Problems of Architecture and Construction

The article presents the results of experimental studies of the mechanism of force transmission through cracks in reinforced concrete elements strengthened with external reinforcement from carbon-fiber materials. New results to assess the ultimate shear resistance and stiffness of sections of reinforced concrete elements with cracks are described.


Prospects And Possibilities Of Use Of Composite Materials In Construction Production In The Republic Of Uzbekistan, B. Matniyazova, Kh. Matniyazov Jan 2019

Prospects And Possibilities Of Use Of Composite Materials In Construction Production In The Republic Of Uzbekistan, B. Matniyazova, Kh. Matniyazov

Problems of Architecture and Construction

In this article we observed the modern construction composition materials on the basis of wood particles, which given on the examples of the large researches and the development in this area in chair “Processing of wood materials” in Kazan technological university and in the chair of “Technology of building materials articles and construction” in Jizzakh polytechnic institute.


Interlaminar Damage Detection In Composite Materials, Hariharan Rangarajan Jan 2019

Interlaminar Damage Detection In Composite Materials, Hariharan Rangarajan

Williams Honors College, Honors Research Projects

Using ceramic matrix composites (CMCs) for high-temperature applications in jet engines increases durability and reduces weight and cooling requirements resulting in improved efficiency and fuel savings. Understanding, detecting, and monitoring different types of damage is essential to achieve optimal performance of CMC components. The Direct Current Potential Drop (DCPD) method is a non-destructive technique of estimating damage in composite materials.

DCPD technique works by measuring nodal potential differences when current is flown through the material. Direct current spreading in different woven and laminate composites is modeled to follow a ladder resistor network in which the nodal voltages decrease exponentially as …


Form Stable Phase-Change Materials, Russell Dent, Marjan Kashfipour, Nitin Mehra, Jiahua Zhu Jan 2019

Form Stable Phase-Change Materials, Russell Dent, Marjan Kashfipour, Nitin Mehra, Jiahua Zhu

Williams Honors College, Honors Research Projects

This work investigates the use of two different polyols, xylitol (Xyl) and erythritol (Ery), in conjunction with boron nitride (BN) aerogels, for the purpose of creating thermally conductive composites. While the BN filler in Xyl composites achieved a high anisotropic thermal conductivity of up to 4.53 W/m-K at 18.2 weight percent filler loading, they do not exhibit good phase-change material qualities due to a low solidification enthalpy even at low cooling rates. Alternatively, the BN-Ery composites have shown promising results with a solidification enthalpy of 225.14 J/g and a melting enthalpy of 385.84 J/g at a heat rate of 5 …


Effective Magnetic And Electric Response Of Composite Materials, Mona Hassan Alsaleh Nov 2018

Effective Magnetic And Electric Response Of Composite Materials, Mona Hassan Alsaleh

Doctoral Dissertations

Metamaterials (MMs) are nanocomposite materials consisting of metal-dielectric resonators much smaller in size than the wavelength of the incident light. Common examples of metamaterials are based on split ring resonators (SRRs), parallel wires or strips and fishnet structures. These types of materials are designed and fabricated in order to provide unique optical responses to the incident electromagnetic radiation that are not available in naturally existing materials. The MMs can exhibit unusual properties such as strong magnetism at terahertz (THz) and optical frequencies. Additionally, negative index materials (NIMs) can provide negative index of refraction which can be used in many applications …