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Full-Text Articles in Engineering Science and Materials

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

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 ...


Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu Jan 2019

Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu

Mechanical & Materials Engineering Faculty Publications

The objective of this study is to characterize the micromechanical properties of poly-L-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 μm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus ...


Characterization Of 3d Printed Polylactic Acid/ Polycaprolactone/Titanium Dioxide Composites For Bone Replacement And Grafting, Sandra Elena Najera Beltran Jan 2018

Characterization Of 3d Printed Polylactic Acid/ Polycaprolactone/Titanium Dioxide Composites For Bone Replacement And Grafting, Sandra Elena Najera Beltran

Open Access Theses & Dissertations

A material that mimics the properties of bones was developed by optimizing the ratio of polymer composites of polylactic acid (PLA) and poly-ε-caprolactone (PCL), containing small amounts of titanium oxide (TiO2). Although titanium-based alloys have commonly been used for bone replacement procedures due to their biocompatibility with the human body and their mechanical properties, stress shielding continues to be a problem. The structure of a bone has a porosity which permits the flow of nutrients, blood, oxygen and minerals, and is an issue at the time of creating bone replacements using conventional methods. PLA and PCL have been used in ...


3d Printing Of 316l Stainless Steel And Its Effect On Microstructure And Mechanical Properties, Rawn Penn Oct 2017

3d Printing Of 316l Stainless Steel And Its Effect On Microstructure And Mechanical Properties, Rawn Penn

Graduate Theses & Non-Theses

Laser powder bed fusion or 3D printing is a potential candidate for net shape forming and manufacturing complex shapes. Understanding of how various parameters affect build quality is necessary. Specimens were made from 316L stainless steel at 0°, 30°, 60°, and 90° angles measured from the build plate. Three tensile and four fatigue specimens at each angle were produced. Fracture morphology investigation was performed to determine the fracture mode of specimens at each build angle. Microstructural analysis was performed on one of each orientation. The average grain size of the samples was marginally influenced by the build angle orientation. Tensile ...


Role Of Interphase In The Mechanical Behavior Of Silica/Epoxy Resin Nanocomposites, Yi Hua, Linxia Gu, Sundaralingam Premaraj, Xiaodong Zhang Jan 2015

Role Of Interphase In The Mechanical Behavior Of Silica/Epoxy Resin Nanocomposites, Yi Hua, Linxia Gu, Sundaralingam Premaraj, Xiaodong Zhang

Mechanical & Materials Engineering Faculty Publications

A nanoscale representative volume element has been developed to investigate the effect of interphase geometry and property on the mechanical behavior of silica/epoxy resin nanocomposites. The role of interphase–matrix bonding was also examined. Results suggested that interphase modulus and interfacial bonding conditions had significant influence on the effective stiffness of nanocomposites, while its sensitivities with respect to both the thickness and the gradient property of the interphase was minimal. The stiffer interphase demonstrated a higher load-sharing capacity, which also increased the stress distribution uniformity within the resin nanocomposites. Under the condition of imperfect interfacial bonding, the effective stiffness ...


Thermal Shock Studies On Carbon-Carbon Composites: Experimentation And Analysis, Alma Lucia Leanos Jan 2015

Thermal Shock Studies On Carbon-Carbon Composites: Experimentation And Analysis, Alma Lucia Leanos

Open Access Theses & Dissertations

The oxidation behavior of C/C composites under thermal shock conditions in air is understood and predicted experimentally and by computational efforts. In Chapter. 1, both compressive properties and oxidation behavior of pristine and thermal shock exposed 2D C/C composite specimens were examined. Pristine test specimens were exposed to thermal shock conditions with temperatures ranging from 400°C to 1000°C in an oxidizing environment, followed by compression tests on pristine and thermal shock exposed specimens to obtain their compressive responses.

Similarly, in Chapter. 2, the influence of thermal shock conditions on both, the extent of carbon materials decomposition ...


Single Fiber Mechanical Properties Using Nano-Tensile Testing And Carbon Fiber Structure-Property Relationship, Matthew Erich Kant Dec 2014

Single Fiber Mechanical Properties Using Nano-Tensile Testing And Carbon Fiber Structure-Property Relationship, Matthew Erich Kant

Doctoral Dissertations

Single carbon fibers are studied using a nano-tensile testing system. This system has unprecedented load and displacement resolution, nN and nm respectively, and the ability to perform dynamic testing for storage and loss modulus during quasi-static tensile extension. Furthermore, improved fiber mounting and alignment procedures coupled with the precision of the nano-tensile testing system assist in unprecedented resolution in single fiber mechanical testing for axial modulus and strength. Hence, using these unique capabilities, the moduli and their statistical distribution of many high performance carbon fibers are reported here. From this, a simplified single parameter model describing the strain dependent modulus ...


Nanoparticle-Shelled Bubbles For Lightweight Materials, Teresa Brugarolas Brufau Jan 2014

Nanoparticle-Shelled Bubbles For Lightweight Materials, Teresa Brugarolas Brufau

Publicly Accessible Penn Dissertations

Lightweight materials that are mechanically robust are of great interest in automotive, aerospace, and construction industries. However due to the nature of materials, it is challenging to obtain materials that have high strength, stiffness and toughness, and light weight simultaneously. One approach that tries to address this limitation is the use of composite materials containing hollow microparticles, also known as syntactic foams. The incorporation of hollow microparticles decreases the density of the material at the same time that increases its specific strength. Conventional methods of fabrication of hollow particles involving bulk reactions result in high heterogeneity in geometry as well ...


Polyurethane Films, Foams And Nanocomposites Prepared From Vegetable Oil-Based Polyols, Chaoqun Zhang Jan 2014

Polyurethane Films, Foams And Nanocomposites Prepared From Vegetable Oil-Based Polyols, Chaoqun Zhang

Graduate Theses and Dissertations

ABSTRACT

Polyurethanes (PUs) have been widely used in coatings, adhesives, sealants, and foams. Historically, the raw materials of a PU, polyol and isocyanate, were derived from petroleum. Nowadays, the increasing concerns regarding the depletion of petroleum resources and environmental problems caused by fossil fuels, has triggered great interest in the development of monomers based on renewable resources for PU production. In this project, a novel solvent-free/catalyst-free method was developed to prepare polyols from epoxidized soybean oil and castor oil for PU production. The effects of reaction temperature, reaction time, and reaction ratios of carboxyl acid and epoxy groups on ...


Study Of Mechanical And Thermal Properties Of Soy Flour Elastomers, Kendra Allen Jan 2014

Study Of Mechanical And Thermal Properties Of Soy Flour Elastomers, Kendra Allen

Graduate Theses and Dissertations

Bio-based plastics are becoming viable alternatives to petroleum-based plastics because they decrease dependence on petroleum derivatives and are more environmentally friendly. Raw materials such as soy flour are widely available, low cost, lightweight, stiffness and have high strength characteristics, but weak interfacial adhesion between the soy flour and the polymer poses a challenge. In this study, soy flour was utilized as a filler in thermoplastic elastomer composites. A surface modification called acetylation was investigated at soy flour concentrations of 10 wt%, 15 wt% and 20 wt%. The mechanical properties of the composites were then compared to that of elastomers without ...


The Electronic And Mechanical Properties Of The Xyb14 Complex Borides Studied By First-Principles Methods, Liwen Wan Jan 2013

The Electronic And Mechanical Properties Of The Xyb14 Complex Borides Studied By First-Principles Methods, Liwen Wan

Graduate Theses and Dissertations

Intensive scientific efforts have been invested in searching and designing new superhard materials for applications as abrasives, polishing and cutting tools, wear-resistant and protective coatings. The best-known superhard material to date is diamond. However, its industrial applications are greatly limited by its high cost and susceptibility to chemical corrosion. Alternatively, boron compounds are promising candidates because of boron's hardness and excellent chemical and thermal stability.

Conventional superhard materials, such as diamond and cubic boron nitride, are usually comprised of a strong, covalently bonded network of atoms. This bonding usually results in a dense, highly symmetric crystal structure that is ...


Influence Of Co2 Laser Radiation On The Mechanical Properties Of Portland Cement Pastes, Maria Del Rosario Moreno-Virgen, Juan José Soto-Bernal, José A. Ortíz-Lozano, Adrian Bonilla-Petriciolet, José Vega-Duran, Rosario González-Mota, José Pineda-Piñon Dec 2010

Influence Of Co2 Laser Radiation On The Mechanical Properties Of Portland Cement Pastes, Maria Del Rosario Moreno-Virgen, Juan José Soto-Bernal, José A. Ortíz-Lozano, Adrian Bonilla-Petriciolet, José Vega-Duran, Rosario González-Mota, José Pineda-Piñon

Adrian Bonilla-Petriciolet

This article presents the results of the treatment of fresh cement pastes with CO2 laser radiation (10.6μm), in order to improve its mechanical properties in addition to obtaining lower setting times than those of a natural setting (without radiation). It was observed that the CO2 laser radiation has a positive influence on the mechanical properties of cement paste, not due to the heat produced during irradiation, but due to the effect of electric field propagation on water molecules, whose are arranged around functional groups of the binder and by the effect of ration, causes a micro vibration effect, resulting ...


Processing, Microstructure And Mechanical Behavior Of Nanocomposite Multilayers, Zuqiang Qi Jan 2004

Processing, Microstructure And Mechanical Behavior Of Nanocomposite Multilayers, Zuqiang Qi

LSU Doctoral Dissertations

Nanoscale multilayer coatings have high potential for numerous engineering applications because they can exhibit enhanced properties due to nanoscale effects and combine different properties from individual components. At present, scale effects on the mechanical behavior of multilayers are not well understood. Three multilayer nanocomposite systems, namely Al/Al2O3, Ti/TiN, and Cr/a-C, have been synthesized by using a dual-gun e-beam physical vapor deposition, to investigate the effect of layer thickness, the nature of components and their microstructures on the mechanical behavior. The deposited Al and Ti nanolayers were found to have polycrystalline fcc and hcp structure, respectively, the Cr ...