Effect of Topological Defects on Buckling Behavior of Single-walled Carbon Nanotube

Molecular dynamic simulation method has been employed to consider the critical buckling force, pressure, and strain of pristine and defected single-walled carbon nanotube (SWCNT) under axial compression. Effects of length, radius, chirality, Stone–Wales (SW) defect, and single vacancy (SV) defect on buckling behavior of SWCNTs have been studied. Obtained results indicate that axial stability of SWCNT reduces significantly due to topological defects. Critical buckling strain is more susceptible to defects than critical buckling force. Both SW and SV defects decrease the buckling mode of SWCNT. Comparative approach of this study leads to more reliable design of nanostructures

Mechanical stability of Carbon Nanotubes

University of Technology, Sydney. Department of Chemistry and Forensic SciencesNO FULL TEXT AVAILABLE. Access is restricted indefinitely. The hardcopy may be available for consultation at the UTS Library.NO FULL TEXT AVAILABLE. Access is restricted indefinitely. ----- Consideration of stability of carbon nanotubes (CNTs) as one dimensional carbon based materials and building blocks of numerous advanced devices and potential components of many more instruments is the subject of this project. CNTs are cylindrical structure with honey comb lattice that gives them exceptional mechanical, electrical, chemical and thermal properties which distinguish them from other known material as the most promising material for numerous advanced applications such as composite materials, hydrogen storage, electron microscopy, optoelectronic, etc. However, before practical application of CNTs as components of future materials and devices, their mechanical properties and especially their mechanical stabilities should be investigated in detail. Molecular dynamics simulation and continuum mechanics are two common theoretical approaches which have been employed herein to study the mechanical properties of CNTs. Buckling behaviour and critical axial properties of single-, double-, and multi-walled carbon nanotubes have been studied. Axial and bending stability of double-walled carbon nanotube and its inner and outer tubes with different dimensions and mechanical properties in different buckling modes have been considered. Effects of surrounding elastic medium on the outer tube and the van der Waals interaction between adjacent tubes of multi-walled CNTs and growth in the radius, length, and aspect ratio (length/radius) on the stability of CNTs have been considered thoroughly. Stress-strain curves, elastic modulus, tensile, compressive and bending stiffness of zigzag and armchair CNTs are investigated to figure out the effect of variation in radius and different chirality on mechanical properties of CNTs. Effects of van der Waals interaction and variation in dimensions of CNTs on Young’s modulus, compressive elastic modulus, tensile, compressive, and lateral stiffness, critical buckling strain, critical axial force and pressure of armchair and zigzag CNTs have been investigated. Destructive effects of Stone-Wales, atom vacancy, cell vacancy and cell deformed structural defects on axial and bending stability and buckling behaviour of armchair and zigzag CNTs have been studied Obtained results revealed remarkable agreement between predictions of continuum mechanics analysis and molecular dynamics simulation results. CNTs with different dimensions revealed different mechanical properties and different level of stability against mechanical loading conditions; however, obtained results of this study categorized their properties and found relationships between variations in lengths and radius with alterations in mechanical stabilities and mechanical properties of CNTs. Consideration of destructive effects of defects on the stability of CNTs led to more reliable predictions about the resilience of CNTs under axial forces and bending moments. Comparative style of this study facilitates selection of suitable size and chirality of CNTs for in nanostructures, nanoelectromecanical devices, and numerous other practical applications of CNTs

Molecular dynamic investigation of length dependency of single-walled carbon nanotube

This paper investigates the effects of length's variations on Young's modulus, compressive elastic modulus, tensile, compressive, and lateral stiffness, critical buckling strain, critical axial force and pressure of armchair and zigzag single-walled carbon nanotubes (SWCNTs). Molecular dynamic simulation (MDS) method employed to analyse the mechanical properties of SWCNTs under tensile, compressive, and lateral loads. Both armchair and zigzag SWCNTs demonstrate higher tensile properties than compressive properties. Buckling modes of SWCNTs change with the length. Critical buckling strain of armchair nanotube is higher than that of zigzag type. Stiffness of SWCNTs is independent of length and chirality whereas elastic modulus increases with increase in nanotube's length. © 2010 Elsevier B.V

Bending stability of inner and outer tubes of double-walled carbon nanotube

This paper considers the effects of bending moment on the structure of double-walled carbon nanotube (DWCNT). Two types of DWCNTs with almost the same aspect ratio (length/radius) are selected; also continuum modeling is utilized to study the bending stability of inner and outer tubes. As a result of the van der Waals interaction between adjacent tubes the critical bending moment of inner tube is higher than this moment of outer tube which is indicated from the obtained results of this research; thus, achieving higher reliability in nanostructures, the critical bending moment of outer tube should be taken into account. © 2009 World Scientific Publishing Company

Molecular dynamic investigation of mechanical properties of armchair and zigzag double-walled carbon nanotubes under various loading conditions

Using molecular dynamic simulation (MDS), effects of chirality and Van der Waals interaction on Young's modulus, elastic compressive modulus, bending, tensile, and compressive stiffness, and critical axial force of double-walled carbon nanotube (DWCNT) and its inner and outer tubes are considered. Achieving the highest safety factor, mechanical properties have been investigated under applied load on both inner and outer tubes simultaneously and on each one of them separately. Results indicate that as a compressive element, DWCNT is more beneficial than single-walled carbon nanotube (SWCNT) since it carries two times higher compression before buckling. Except critical axial pressure and tensile stiffness, in other parameters zigzag DWCNT shows higher amounts than armchair type. Outer tube has lower strength than inner tube; therefore, most reliable design of nanostructures can be attained if the mechanical properties of outer tube taken as the properties of DWCNT. © 2009 Elsevier B.V. All rights reserved

Practical molecular dynamic simulation of monolayer graphene with consideration of structural defects

Molecular dynamic simulation method has been employed to consider the mechanical properties of pristine and defected armchair and zigzag monolayer graphene sheets under tension and compression. Effects of Stone Wales (SW), Cell deformed (CD) and cell vacancy (CV) defects on ultimate stress and strain of graphene sheets have been considered. Obtained results indicate that zigzag graphene sheet has higher elastic modulus and stiffness than armchair type. Three SW defects have the highest destructive effect on ultimate stress and strain of zigzag graphene sheet while CV defect reveals the highest reducing effect on those of armchair type. Copyright © 2012 American Scientific Publishers

Consideration of bending and buckling behaviors of monolayer and multilayer graphene sheets

Graphene is a two-dimensional carbon based material. Remarkable mechanical, thermal and electrical properties of graphene make it as promising material for advanced applications; nevertheless, majority of its mechanical properties are still unknown. This research investigates buckling and bending behaviors of monolayer and multilayer armchair and zigzag graphene sheets. Bending stiffness, critical buckling force per unit length and critical strain of graphene sheets have been measured by molecular dynamic simulation method. Zigzag graphene sheet shows higher bending stiffness than armchair sheet. Van der Waals interaction between graphene sheets has an improving effect on the stability of middle layers. Cross-linkages reduce the buckling force per unit length and the buckling strain of multi layer graphene sheets. Copyright © 2012 American Scientific Publishers

Consideration of mechanical properties of single-walled carbon nanotubes under various loading conditions

In this article, mechanical properties of single-walled carbon nanotubes (SWCNTs) with various radiuses under tensile, compressive and lateral loads are considered. Stress–strain curve, elastic modulus, tensile, compressive and rotational stiffness, buckling behaviour, and critical axial compressive load and pressure of eight different zigzag and armchair SWCNTs are investigated to figure out the effect of radius and chirality on mechanical properties of nanotubes. Using molecular dynamic simulation (MDS) method, it can be explained that SWCNTs have higher Young’s modulus and tensile stiffness than compressive elastic modulus and compressive stiffness. Critical axial force of zigzag SWCNT is independent from the radius, but that of armchair type rises by increasing of radius, also these two types show different buckling modes

Consideration of critical axial properties of pristine and defected carbon nanotubes under compression

Carbon nanotubes are hexagonally configured carbon atoms in cylindrical structures. Exceptionally igh mechanical strength, electrical conductivity, surface area, thermal stability and optical transparency of carbon nanotubes outperformed other known materials in numerous advanced applications. However, their mechanical behaviors under practical loading conditions remain to be demonstrated. This study investigates the critical axial properties of pristine and defected single-and multi-walled carbon nanotubes under axial compression. Molecular dynamics simulation method has been employed to consider the destructive effects of Stone-Wales and atom vacancy defects on mechanical properties of armchair and zigzag carbon nanotubes under compressive loading condition. Armchair carbon nanotube shows higher axial stability than zigzag type. Increase in wall number leads to less susceptibility of multi-walled carbon nanotubes to defects and higher stability of them under axial compression. Atom vacancy defect reveals higher destructive effect than Stone-Wales defect on mechanical properties of carbon nanotubes. Critical axial strain of single-walled arbon nanotube declines by 67% and 26% due to atom vacancy and Stone-Wales defects. Copyright © 2012 American Scientific Publishers. All rights reserved

Controlled size and shape of graphene and its application in li-ion battery

Graphene is one-atom-thick film of carbon atoms packed in honeycomb structure with exceptional electrical, thermal, optical, and mechanical properties, which opened up new horizons for next generation nanotechnology-based devices. Two University of Manchester scientists, Andre Geim and Konstantin Novoselov, were awarded the 2010 Nobel Prize in physics "for groundbreaking experiments regarding the two-dimensional material graphene". This chapter reviews the brief history and development of graphene, considers its properties, characterizations and the synthesis methods, and provides a few examples for its advanced application in lithium-ion battery. © 2013 Pan Stanford Publishing Pte. Ltd. All rights reserved