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Author:
Publisher:
ISBN:
Category : Continuum mechanics
Languages : en
Pages : 32
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Book Description
A method has been proposed for developing structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As important examples with direct application to the development and characterization of single-walled carbon nanotubes and the design of nanotube-based devices, the modeling technique has been applied to determine the effective-continuum geometry and bending rigidity of a graphene sheet, A representative volume element of the chemical structure of graphene has been substituted with equivalent-truss and equivalent-continuum models. As a result, an effective thickness of the continuum model has been determined.
Author:
Publisher:
ISBN:
Category : Continuum mechanics
Languages : en
Pages : 32
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Book Description
A method has been proposed for developing structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As important examples with direct application to the development and characterization of single-walled carbon nanotubes and the design of nanotube-based devices, the modeling technique has been applied to determine the effective-continuum geometry and bending rigidity of a graphene sheet, A representative volume element of the chemical structure of graphene has been substituted with equivalent-truss and equivalent-continuum models. As a result, an effective thickness of the continuum model has been determined.
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723723605
Category : Science
Languages : en
Pages : 32
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Book Description
A method has been proposed for developing structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As important examples with direct application to the development and characterization of single-walled carbon nanotubes and the design of nanotube-based devices, the modeling technique has been applied to determine the effective-continuum geometry and bending rigidity of a graphene sheet. A representative volume element of the chemical structure of graphene has been substituted with equivalent-truss and equivalent continuum models. As a result, an effective thickness of the continuum model has been determined. This effective thickness has been shown to be significantly larger than the interatomic spacing of graphite. The effective thickness has been shown to be significantly larger than the inter-planar spacing of graphite. The effective bending rigidity of the equivalent-continuum model of a graphene sheet was determined by equating the vibrational potential energy of the molecular model of a graphene sheet subjected to cylindrical bending with the strain energy of an equivalent continuum plate subjected to cylindrical bending.Odegard, Gregory M. and Gates, Thomas S. and Nicholson, Lee M. and Wise, Kristopher E.Langley Research CenterCARBON NANOTUBES; CONTINUUM MODELING; SOLID MECHANICS; NANOTECHNOLOGY; GRAPHITE; POTENTIAL ENERGY; TRUSSES; VIBRATION; BENDING
Author: Gregory M. Odegard
Publisher:
ISBN:
Category : Nanostructured materials
Languages : en
Pages : 38
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Book Description
A method has been developed for modeling structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with an equivalent-continuum model. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As an important example with direct application to the development and characterization of single-walled carbon nanotubes, the model has been applied to determine the effective continuum geometry of a graphene sheet. A representative volume element of the equivalent-continuum model has been developed with an effective thickness. This effective thickness has been shown to be similar to, but slightly smaller than, the interatomic spacing of graphite.
Author: Q. Wang
Publisher:
ISBN: 9788178954295
Category :
Languages : en
Pages : 201
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Book Description
Carbon nanotubes are macromolecules of carbon in a periodic hexagonal arrangement with a cylindrical shell shape. Carbon nanotubes have been subjected to extensive research, with subsequent predictions of extremely high strength and exceptional electronic and thermal properties. They also hold substantial promise as fibers in composites and other devices for the development of superconductive devices for micro-electro-mechanical and nano-electro-mechanical system applications. It is expected that the material has great potential in biological, medical, energy storage, sensor, and other applications. It has been broadly recognized that atomic modeling of carbon nanotube is a powerful tool for analysis of carbon nanotube. Due to massive computations involved, the atomic modeling is limited to systems with a small number of molecules and atoms. On the other hand, attempts at applying continuum mechanics models to better investigate the analysis of carbon nanotube with large sizes have been initiated. However, continuum models are unable to adequately capture the atomic structures of carbon nanotube, and the applicability of the models needs to be justified. Recently, developments of multiscale methods have been proposed to the analysis of carbon nanotube. This book is dedicated to the publication of recent developments in modeling of carbon nanotube via atomic modeling, continuum modeling and multiscale methods for predictions of mechanical, electronic, and thermal properties of carbon nanotube. A wide range of fundamentally theoretical, computational topics on modeling and applications of carbon nanotube will be covered in the book. In addition, applications of carbon nanotubes as nano-devices in atomic and molecular transportations and bistable devices in switching or memory elements in signal processing and communications are also reported. It is with great pleasure that we present this book that covers a very wide and varied range of subject areas in modeling and applications of carbon nanotubes. The first chapter employs molecular dynamics simulations to show macroscopic flows of atomic and molecular hydrogen, helium, and a mixture of both gases both inside and outside a carbon nanotube. In particular, the simulations show a nanoseparation effect of the two gases. The new results in the chapter show the mass selectivity of the nanopumping effect can be used to develop a highly selective filter for various gases. The second chapter introduces a fine continuum model that is developed by virtue of the higher-order continuum theory. Moreover, a mesh-free computational framework is developed to implement the numerical simulation of single- walled carbon nanotubes. The rationality of the higher-order continuum model and the efficiency of mesh-free method are illustrated and discussed in the chapter. The study on the mechanics of buckled single-walled and multiwalled carbon nanotubes, carbon nanotube bundles and coupling effect between adjacent carbon nanotubes is reported in chapter three. Simple expressions of the buckle wavelength, amplitude and critical strain for buckling are given analytically, which show good agreement with experiments. Chapter 4 investigate the applicability of elastic shell model in analysis of graphene and carbon nanotubes. The author reports that the elasticity of graphene should be modeled as a shell composed of 2-dimensional (2D) isotropic materials with proper parameters rather than conventional 3D materials based on calculations by density functional theory. In addition, the elasticity of single-walled carbon nanotube with relative large radius can also be modeled as a shell composed of 2D isotropic materials, whereas the elasticity of single-walled carbon nanotubes with relative small radius should be modeled as a more complicated shell with seven elastic constants rather than the orthotropic thin shell. Mechanical integrity of carbon nanotubes is summarized in chapter 5. Young s modulus for the resistance to the infinitesimal deformation and ultimate strength to the finite deformation are tabled, which have been obtained by experiments, molecular dynamics simulations, and ab-initio calculations. Also the recent continuous modeling of carbon nanotubes is sorted out in tracing its advancement in the chapter. Chapter 6 presents an overview of studies on the wave propagation and the vibrational properties in carbon nanotubes by computational modeling and simulation. The models include the atomic-based continuum model, the Euler-beam model, the Timoshenko beam model, and the three-dimensional elastic shell model. Chapter seven reports the investigations of torsional buckling of both single-walled and double-walled carbon nanotubes. In the study of doubled-walled carbon nanotubes via molecular dynamics, a newly revealed buckling mode with one or three thin local rims on the outer tube is discovered while the inner tube shows a helically aligned buckling mode in three dimensions. The distinct buckling modes of the two tubes imply the inapplicability of continuum mechanics modeling in which it is postulated that the buckling modes of the constituent tubes have the same shape. The mechanical properties of single walled carbon nanotubes under both tensile and torsion are investigated using classical molecular dynamics simulations in chapter 8, based on reactive empirical bond-order potential. Based on the predicted mechanical properties, it is predicted that nanotubes may represent new candidates for novel porous, flexible and high strength and tough materials, e.g. ideal as scaffolds in the regenerative medicine. Bistable devices have been widely used as switching or memory elements in signal processing and communications. The bistablity is generally realized electrically or optically. Due to their small size and unique mechanical properties, carbon nanotubes have been proposed to form bistable devices mechanically. The chapter 9 reviews the recent advances of mechanical bistable devices of carbon nanotubes. In the final chapter, the authors have discussed a theoretical model based on kinetic concept of fracture of solids and molecular mechanics simulations for studying the time-dependent behavior of single-walled carbon nanotubes. The major advantage of this model is that the problem of real-time molecular level simulation is circumvented. Compared with recently published data on creep rupture of SWCNT ropes, it is seen that the predictions by the present model is quite reasonable, thus setting up a framework for modeling the time-dependent behavior of carbon nanotubes and their composites. We would like to extend our sincere thanks to the authors for their contributions, especially their precious time and efforts invested in the book. We also would like to thank Transworld Research Network Publishers for the opportunity to publish the book to address very important and challenging issues. The support and love from our families are deeply appreciated.
Author: Konstantinos I. Tserpes
Publisher:
ISBN: 9783319012025
Category :
Languages : en
Pages : 346
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Book Description
Author: Frank Abdi
Publisher: CRC Press
ISBN: 1315341247
Category : Science
Languages : en
Pages : 292
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Book Description
These days, advanced multiscale hybrid materials are being produced in the industry, studied by universities, and used in several applications. Unlike for macromaterials, it is difficult to obtain the physical, mechanical, electrical, and thermal properties of nanomaterials because of the scale. Designers, however, must have knowledge of these properties to perform any finite element analysis or durability and damage tolerance analysis. This is the book that brings this knowledge within easy reach. What makes the book unique is the fact that its approach that combines multiscale multiphysics and statistical analysis with multiscale progressive failure analysis. The combination gives a very powerful tool for minimizing tests, improving accuracy, and understanding the effect of the statistical nature of materials, in addition to the mechanics of advanced multiscale materials, all the way to failure. The book focuses on obtaining valid mechanical properties of nanocomposite materials by accurate prediction and observed physical tests, as well as by evaluation of test anomalies of advanced multiscale nanocomposites containing nanoparticles of different shapes, such as chopped fiber, spherical, and platelet, in polymeric, ceramic, and metallic materials. The prediction capability covers delamination, fracture toughness, impact resistance, conductivity, and fire resistance of nanocomposites. The methodology employs a high-fidelity procedure backed with comparison of predictions with test data for various types of static, fatigue, dynamic, and crack growth problems. Using the proposed approach, a good correlation between the simulation and experimental data is established.
Author: Isaac Elishakoff
Publisher: John Wiley & Sons
ISBN: 1118565886
Category : Technology & Engineering
Languages : en
Pages : 308
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Book Description
The main properties that make carbon nanotubes (CNTs) a promising technology for many future applications are: extremely high strength, low mass density, linear elastic behavior, almost perfect geometrical structure, and nanometer scale structure. Also, CNTs can conduct electricity better than copper and transmit heat better than diamonds. Therefore, they are bound to find a wide, and possibly revolutionary use in all fields of engineering. The interest in CNTs and their potential use in a wide range of commercial applications; such as nanoelectronics, quantum wire interconnects, field emission devices, composites, chemical sensors, biosensors, detectors, etc.; have rapidly increased in the last two decades. However, the performance of any CNT-based nanostructure is dependent on the mechanical properties of constituent CNTs. Therefore, it is crucial to know the mechanical behavior of individual CNTs such as their vibration frequencies, buckling loads, and deformations under different loadings. This title is dedicated to the vibration, buckling and impact behavior of CNTs, along with theory for carbon nanosensors, like the Bubnov-Galerkin and the Petrov-Galerkin methods, the Bresse-Timoshenko and the Donnell shell theory.
Author: Hashem Rafii-Tabar
Publisher: Cambridge University Press
ISBN: 0521853001
Category : Technology & Engineering
Languages : en
Pages : 477
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Book Description
This book presents the key theories, computational modelling and numerical simulation tools required to understand carbon nanotube physics. Specifically, methods applied to geometry and bonding, mechanical, thermal, transport and storage properties are addressed. This self-contained book will interest researchers across a broad range of disciplines.
Author: Gregory M. Odegard
Publisher:
ISBN:
Category : Nanostructured materials
Languages : en
Pages : 20
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Book Description
In this study, a technique has been proposed for developing constitive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method.
Author: Vasyl Harik
Publisher: Academic Press
ISBN: 0128110724
Category : Technology & Engineering
Languages : en
Pages : 326
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Book Description
Mechanics of Carbon Nanotubes: Fundamentals, Modeling and Safety draws on the latest academic research and nanotechnology applications to provide a comprehensive guide on the most recent developments in the science of carbon nanotubes. The fundamentals of nanomechanics and mechanical behavior of carbon nanotubes are presented in initial chapters, followed by more advanced topics such as the classification of carbon nanotubes, carbon nanotubes in nanocomposites, multiwall carbon nanotubes, and recent trends. This book provides a system for the classification of carbon nanotubes into 20 classes, aiding correct selection for various applications, and includes the Atomic Registry Matrix Analysis for nanoscale interfaces, essential for design involving friction or sliding. Parametric maps are included to help readers pick the correct model for a particular CNT geometry, in addition to a thorough examination of the effective thickness paradox and safety issues related to CNTs, such as toxicity at high aspect ratio. Mechanics of Carbon Nanotubes is essential reading for anyone involved in research or engineering that includes carbon nanotubes, be they students or seasoned professionals in the field. It is particularly useful to those working with applications in the areas of microelectronics, robotics, aerospace, composites, or prosthetics. Provides a system for the classification of carbon nanotubes, aiding correct selection for various applications Includes the Matrix Registry Analysis for nanoscale interfaces that is essential for design involving friction or sliding Features parametric maps to help readers pick the right model for a particular CNT geometry (beam vs. shell vs. thin or thick shells, etc.) Presents a thorough examination of the safety issues related to CNTs, including toxicity at high aspect ratio
