基于分子动力学的碳纳米管屈曲性能的研究
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摘要
本文利用LAMMPS软件研究了扶手椅型单壁碳纳米管受轴向载荷压缩时的屈曲性能.通过对比分析完美碳纳米管与含S-W缺陷碳纳米管在受压时的力学性能,揭示出不同温度和S-W缺陷的不同分布方式对碳纳米管屈曲性能的影响规律.研究结果表明:碳纳米管的屈曲性能随着温度的升高而明显变差,这种影响在低温区尤为显著,碳纳米管的弹性模量受温度的影响很小;相同缺陷个数下,周向分布的S-W缺陷比轴向分布的S-W缺陷对碳纳米管屈曲性能的影响要大;在轴向方向上,均匀分布、集中分布和非均匀分布的S-W缺陷对碳纳米管的力学性能产生的影响类似,在周向方向上,集中分布对碳纳米管力学性能的影响比均匀分布的要大.
In this paper,the buckling properties of armchair single-walled carbon nanotubes subjected to axial compression was studied by using LAMMPS software. By comparing the mechanical properties of perfect carbon nanotubes and defective carbon nanotubes under compression,the effects of different temperatures and distribution of S-W defects on the buckling properties of carbon nanotubes were revealed. The results show that:the buckling properties of carbon nanotubes become worse with the increase of temperature,especially in the low temperature region,the elastic modulus of carbon nanotubes is little affected by temperature.Under the same number of defects,the S-W defects with circumferential distribution have greater influence on the buckling properties of carbon nanotubes than the S-W defects with axial distribution. In the axial direction,uniform distribution,concentrated distribution and non-uniform distribution of S-W defects have similar effects on the mechanical properties of carbon nanotubes. In the circumferential direction,concentrated distribution has greater influence on the mechanical properties of carbon nanotubes than uniform distribution.
In this paper,the buckling properties of armchair single-walled carbon nanotubes subjected to axial compression was studied by using LAMMPS software. By comparing the mechanical properties of perfect carbon nanotubes and defective carbon nanotubes under compression,the effects of different temperatures and distribution of S-W defects on the buckling properties of carbon nanotubes were revealed. The results show that:the buckling properties of carbon nanotubes become worse with the increase of temperature,especially in the low temperature region,the elastic modulus of carbon nanotubes is little affected by temperature.Under the same number of defects,the S-W defects with circumferential distribution have greater influence on the buckling properties of carbon nanotubes than the S-W defects with axial distribution. In the axial direction,uniform distribution,concentrated distribution and non-uniform distribution of S-W defects have similar effects on the mechanical properties of carbon nanotubes. In the circumferential direction,concentrated distribution has greater influence on the mechanical properties of carbon nanotubes than uniform distribution.
引文
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[2]Modi A,Koratkar N,Lass E,et al.Miniaturized gas ionizationsensors using carbon nanotubes[J].Nature,2003,424(6945):171-174.
[3]Rueckes T,Kim K,Joselevich E,et al.Carbon nanotubebased nonvolatile random access memory for molecular computing[J].Science,2000,289(5476):94-97.
[4]Zhang W M,Meng G.Reliability of MEMS and its failure analysis[J].Journal of Mechanical Strength,2005,27(6):855-859.
[5]Yakobson B I,Brabec C J,Berhnolc J.Nanomechanics of carbon tubes:Instabilities beyond linear response[J].Physical Review Letters,1996,76(14):2511-2514.
[6]李琰,朱长纯,姚振华.碳纳米管的分子动力学模拟[J].微细加工技术,2003(1):9-14.
[7]Xie G Q,Han X,Long S Y,et al.Buckling of a single wall carbon nanotube under an axial pressure based on the nonlocal elastic theory[J].ActaPhysicaSinica,2005,54(9):4192-4197.
[8]Yao X,Qiang H.Investigation of axially compressed buckling of a multi-walled carbon nanotube under temperature覱eld[J].Composites Science and Technology,2007,67(1):125-134.
[9]Mielke S L.The role of vacancy defects and holes in the fracture of carbonnanotubes[J].Chemical Physics Letters,2004,390(4-6):413-420.
[10]Hao X,Qiang H,Yao X.Buckling of defective singlewalled and double-walled carbon nanotubes under axial compression by molecular dynamics simulation[J].Composites Science and Technology,2008,68(7):1809-1814.
[11]Pozrikidis C.Effect of the stone wales defect on the structure and mechanical properties of singlewall carbon nanotubes in axial stretch and twist[J].Archive of Applied Mechanics,2009,79(2):113-123.
[12]Xin H,Han Q,Yao X H.Buckling of defective singlewalled and double-walled carbon nanotubes under axial compression by molecular dynamics simulation[J].Composites Science and Technology,2008,68(7-8):1809-1814.
[13]Tersoff J.New empirical approach for the structure and energy of covalent systems[J].Physical Review B,1988,37(12):6991-7000.
[14]Brenner D W.Empirical potential for use in simulating the chemical vapor deposition of diamond films[J].Physical Review B,1990,42(15):9458-9471.
[15]StuartS J,TuteinA B,HarrisonJ A.A reactive potential for hydrocarbons with intermolecular interactions[J].Journal of Chemical Physics,2000,112(14):6472-6486.
[16]BrennerD W,Shenderova O A,Harrison J A,et al.Asecond-generation reactive empirical bond order(REBO)potential energy expression for hydrocarbons[J].Journal of Physics-Condensed Matter,2002,14(4):783-802.