Liu Rumeng, Zhao Junhua, Wang Lifeng
Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University, Wuxi 214122, China.
State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Materials (Basel). 2019 Sep 15;12(18):2986. doi: 10.3390/ma12182986.
The propagation characteristics of terahertz (THz) flexural waves in mass chain-filled single-walled carbon nanotubes (MCSCs) are studied using a continuum mechanics approach and molecular dynamics (MD) simulations, where each single-walled carbon nanotube (SWCNT) is modeled as a nonlocal Timoshenko beam based on the nonlocal strain gradient theory. The effect of the surrounding elastic medium and the van der Waals (vdW) interactions between the mass chain and the SWCNT on the wave propagation is quantitatively considered in governing equations, respectively. The analytical expressions of two flexural wave branches and the bandgap between the two branches are derived. When combining our MD simulations of the carbon-atom chain-filled SWCNT, the wave within the bandgap disperses rapidly, and the mass chain has a significant influence on the phase velocity of the flexural wave. The present theoretical solution has a high accuracy in a wide frequency range up to the THz region. In particular, the surrounding elastic medium of the MCSCs remarkably affects the phase velocity for low frequencies, but not for high frequencies. The present study indicates that the wave propagation of a SWCNT could be modulated by changing the filled mass chain and the surrounding elastic medium.
采用连续介质力学方法和分子动力学（MD）模拟研究了填充质量链的单壁碳纳米管（MCSC）中太赫兹（THz）弯曲波的传播特性，其中基于非局部应变梯度理论将每个单壁碳纳米管（SWCNT）建模为非局部铁木辛柯梁。在控制方程中分别定量考虑了周围弹性介质以及质量链与SWCNT之间的范德华（vdW）相互作用对波传播的影响。推导了两个弯曲波分支的解析表达式以及两个分支之间的带隙。当结合我们对填充碳原子链的SWCNT的MD模拟时，带隙内的波迅速色散，并且质量链对弯曲波的相速度有显著影响。目前的理论解在高达太赫兹区域的宽频率范围内具有很高的精度。特别是，MCSC的周围弹性介质对低频的相速度有显著影响，但对高频则没有影响。本研究表明，SWCNT的波传播可以通过改变填充的质量链和周围弹性介质来调制。
