单壁及双壁纳米碳管径向压缩特性的分子动力学研究

采用Tersoff-Brenner势与L-J势的分子动力学方法,研究了双石墨层作用下(13,0)(、22,0)锯齿形碳管以及它们组合的(13,0)/(22,0)双壁碳管的径向压缩力学特性.根据计算结果,讨论了三种碳管压缩过程中的构型、能量、压缩载荷等的变化及其差异.研究表明,压缩过程中,(22,0)碳管出现了明显的“塌陷”现象,“塌陷”时,能量及外载一度下降;(13,0)/(22,0)碳管的能量吸收能力及承受压缩载荷能力最大;(22,0)碳管的能量吸收能力与承受压缩载荷能力最差,且体积最容易压缩;当压缩应变小于12%时,(13,0)/(22,0)碳管的内管的构型、体积及其能量变化量均很小;内壁与外壁之间的Van der Waals能在整个压缩(13,0)/(22,0)碳管能量变化中仅占很小的份额.

MD simulations of diametrally compressed single-walled and double-walled carbon nanotubes

By the Tersoff-brenner potential based MD(Molecular dynamics) method,the diametral compressive properties of(13,0),(22,0) carbon nanotube and(13,0)/(22,0) double-walled nanotube under the action of graphite layers were investigated.According to the obtained results,the variations and difference of geometrical configurations,energy and external loading for the three carbon-tubes during the compression were discussed.It is shown that,during the compression,the "cave-in" phenomenon only occurs to the(22,0) tube,and at the time of the "cave-in",both the energy and external loading for the(22,0) tube fall;for the same compressive strain,the(13,0)/(22,0) nanotube has the maximal energy-absorbing and carrying compressive loading capability,and the(22,0) tube has the maximal volume-shrinkage,as well as the minimal energy-absorbing and carrying compressive loading capability;when strain is less than 12%,both the variation of the volume and energy of the internal tube in the compressed(13,0)/(22,0) tube are very small;the Van der waals energy between the internal and external tubes of the(13,0)/(22,0) nanotube is still small during the whole compression.