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采用分子动力学模拟方法,研究了多壁碳纳米管振荡器在气体环境下的振动,讨论了气体密度、环境温度对碳管间摩擦力及振荡频率的影响.模拟结果表明,管间摩擦力随气体密度的增大及环境温度的升高而增大.气体分子的碰撞将导致碳管的晶格变形,从而极大改变碳管间的初始理想匹配状态,导致摩擦力增大;随着温度的升高,碳管原子热振动振幅增大和高能量声子的激发,使得碳管振动的机械能更容易转化为热能而被耗散,导致摩擦力增大.气体密度的增大和环境温度的升高,都将导致振幅衰减加快,振荡频率增大.通过与真空状态下的谐振子相比,气体分子与管壁的碰撞是造成能量耗散的一个主要原因,气体环境的阻尼可能是导致碳管谐振子在工程实际中失效的主要原因,其次,环境温度对谐振子也具有重要的影响,低温工作条件对谐振子是有利的.
The molecular dynamics simulation method was used to study the vibration of multi-walled carbon nanotube oscillators in gas environment, and the influence of gas density and ambient temperature on the friction and oscillation frequency between carbon nanotubes was discussed. The simulation results show that the friction between tubes With the increase of gas density and the increase of ambient temperature, the collision of gas molecules will lead to the lattice deformation of carbon nanotubes, which greatly changes the initial ideal match between carbon nanotubes, resulting in increased friction; with The increase of temperature, the increase of the thermal vibration amplitude of carbon nanotubes and the excitation of high-energy phonons make the mechanical energy of the carbon nanotubes more easily converted into heat and dissipated, resulting in an increase of the friction force. The increase of the gas density and the increase of the ambient temperature Will cause the amplitude attenuation to accelerate and the oscillation frequency to increase.The collision of the gas molecules with the tube wall is one of the main causes of the energy dissipation compared with the vacuum state harmonic oscillator.The damping of the gas environment may result in The main reason for the failure of carbon nanotube resonators in engineering practice is, secondly, the ambient temperature also has an important influence on the resonators. The working conditions at low temperature are favorable for the resonators.