共查询到18条相似文献,搜索用时 62 毫秒
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应用改进的有限元方法,建立考虑层间范德华力作用的壳-弹簧非线性有限元模型,基于B-R运动准则,系统地研究了双壁碳纳米管的动力屈曲问题,得到了轴向冲击载荷作用下双壁碳纳米管的临界动力屈曲载荷和临界动力失效载荷. 研究结果表明,在动力屈曲过程中,双壁碳纳米管层间距的变化非常小,各管的变形相互协调;碳纳米管中应力波的传播导致碳纳米管出现非对称屈曲模态,可明显观测到四个环向波瓣,沿着碳纳米管的轴线方向,四个波瓣的波峰和波谷交替变化. 对碳纳米管动力屈曲问题的研究表明,冲击载荷的大小和持续时间对碳纳米管的动力屈曲有
关键词:
碳纳米管
动力屈曲
冲击载荷 相似文献
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使用分子动力学方法研究几种不同半径尺寸的单壁碳纳米管组成的双壁碳管,预测了其初始稳定构型;分析了其自由弛豫阶段的特征;并模拟了它们在轴向压缩载荷作用下的屈曲行为;研究了不同层间距导致的范德华力变化对屈曲行为的影响.采用Tersoff-Brenner势描述单壁碳纳米管内原子间作用,Lennard-Jones势描述内外层间的范德华相互作用.计算结果表明:在通常意义下的双壁管间距(约0.34 nm)外还可以存在稳定的双壁碳管构型,并且这些新的稳定构型表现出了不同的力学性质.
关键词:
双壁碳纳米管
分子动力学
屈曲 相似文献
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本文考虑自旋轨道耦合作用的情况下,采用紧束缚近似螺旋对称模型计算了单壁碳纳米管的电子能带结构.研究发现:对于Armchair型单壁碳纳米管,自旋轨道耦合作用和弯曲效应共同导致了费米面Dirac点附近电子能带结构的能隙;对于Zigzag型和手性单壁碳纳米管,自旋轨道耦合作用使得电子最高占据态和最低未占据态产生能级劈裂,能级劈裂的大小不但与碳纳米管的直径和手性角密切相关,而且相对于费米面是不对称的;根据指数(n,m)可以将Zigzag型和手性单壁碳纳米管分为金属性碳纳米管(ν=0)
关键词:
单壁碳纳米管
自旋轨道耦合
紧束缚近似螺旋对称模型 相似文献
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The present study has theoretically investigated the combined torsional buckling of double-walled carbon nanotubes (DWCNTs) with axial load in the multi-field coupled condition. The effects of torsion, axial load, thermal-electrical change, surrounding elastic medium and the Van der Waals forces are all taken into consideration. The governing equation of buckling for CNTs subjected to thermo-electro-mechanical loadings has been established based on an elastic shell model of continuum mechanics. Reasonable s... 相似文献
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In this Letter, the thermal buckling properties of carbon nanotube with small scale effects are studied. Based on the nonlocal continuum theory and the Timoshenko beam model, the governing equation is derived and the nondimensional critical buckling temperature is presented. The influences of the scale coefficients, the ratio of the length to the diameter, the transverse shear deformation and rotary inertia are discussed. It can be observed that the small scale effects are significant and should be considered for thermal analysis of carbon nanotube. The nondimensional critical buckling temperature becomes higher with the ratio of length to diameter increasing. Furthermore, for smaller ratios of the length to the diameter and higher mode numbers, the transverse shear deformation and rotary inertia have remarkable influences on the thermal buckling behaviors. 相似文献
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《Current Applied Physics》2014,14(8):1072-1077
Based on molecular dynamics simulations, the mechanical properties and buckling behavior of boron-nitride nanotubes under the action of torsional load are investigated. According to the results, the torsional properties of a boron-nitride nanotube are higher than those of its carbon counterpart. The effect of geometrical parameters on these parameters is also investigated. It is observed that by increasing the radius of nanotubes of the same length, unlike the critical shear strain, the critical torque considerably increases. The effect of chirality is also found to be negligible in the cases of critical shear strain and buckling mode, unlike the critical torque. 相似文献
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搅拌摩擦焊接过程中的材料塑性变形流场与温度场对焊接接头的组织演化及最终的力学性能有着十分重要的影响,许多学者对此进行了大量的研究.近年来的研究结果表明,该过程是一个极其复杂的热力耦合过程,温度场与材料塑性变形流场之间具有相互耦合效应.运用流体力学和传热学原理对准稳态热力耦合过程进行了数值模拟研究,通过计算得到了焊件材料的流场和温度场分布,并设计了相关实验对温度场进行了验证,结果表明该计算结果可以较准确地描述搅拌摩擦焊准稳态热力耦合状态. 相似文献