中文摘要：

将N层碳纳米管模拟成N层连续弹性壳模型，研究横向扰动波在单个多壁碳纳米管中轴向传播问题。研究表明，当扰动频率低于多壁碳纳米管的临界频率时，振动模态是同轴的；如果扰动频率至少高于多壁碳纳米管的一个临界频率时，振动模态是非同轴的，并以不同的波速传播，或低或高于单壁连续弹性壳模型的波速。因此，多壁碳纳米管的THz高频波存在着复杂现象，振动基本是不同轴的。特别是当多壁碳纳米管THz高频波以不同的速度传播时，传播速度不仅依赖于频率，而且依赖于非同轴的振动模态。

英文摘要：

A multiple-elastic-shell model is presented for wave propagation estimation along an individual MWCNT. The analysis shows that when the frequency is lower than the critical frequencies of the shells in MWCNT, the vibration mode is almost coaxial. However, when the frequency is higher than at least one of the critical frequencies, non-coaxial vibration modes emerge and these vibrations propagate at various speeds significantly higher or lower than the speed predicted by the single-elastic-shell model. Hence, tetra-hertz waves in MWCNTs are essentially non-coaxial with complex phenomena. Tetra-hertz waves in MWCNTs propagate at various speeds, which depend not only on the frequency, but also on the non-coaxial vibration mode.