Effects Of Defects And Pre-strain On Oscillatory Behavior Of Oscillators Built From Double-walled Carbon Nanotubes

Carbon nanotubes(CNTs)have been widely concerned since their discovery due to the unique mechanical and electrical properties.The super-lubrication characteristic of multiwalled carbon nanotubes(MWCNTs)was proposed that could generate oscillatory frequencies in the gigahertz range.The effects of defects and pre-strain on oscillatory behavior of oscillators built from DWCNTs were investigated by molecular dynamics(MD)method.The following conclusions can be drawn from the present study:(1)Firstly,the influence of vacancy defects on the oscillatory behavior of DWCNTs-based oscillators was analyzed,especially the position,quantity and arrangement of vacancy defects.It was found that the oscillatory behavior of the DWCNT-based oscillators is closely related to the vacancy number and location in case that the vacancies are located in the inner tube.The amplitude and the Q-factor of oscillators decreases gradually,however the oscillation frequency of the oscillators is increasing as the number of vacancies increases.It was also found that the vacancy defects change the off-axial rocking motion and the van der Waals potential,resulting in more energy dissipation.The oscillation of the inner tube is insensitive to the vacancies located in the fixed outer tube.(2)Secondly,the oscillatory behavior of oscillators built from commensurate DWCNTs containing an outer tube or inner tube subject to pre-strain at room temperature was investigated.The result show that the oscillatory behavior of the commensurate DWCNT-based oscillators is closely related to the pre-strain at room temperature.Whatever the commensurate DWCNT-based oscillators is subject to tensile pre-strain or compressive pre-strain,with the increase in the pre-strain,the energy dissipation of the oscillators is significantly accelerated,leading to a faster amplitude attenuation and worse performance.The pre-strain should be eliminated when produce the commensurate DWCNTs-based oscillators at room temperature.(3)Finally,the oscillatory behavior of oscillators built from incommensurate DWCNTs containing an outer tube or inner tube subject to pre-strain at different temperature was investigated.It can be seen from the results that the oscillatory behavior of the incommensurate DWCNT-based oscillators is closely related to the prestrain.the small scale range of strain can improve the Q-factor and stability of incommensurate DWCNTs-based oscillators at low temperature.However,the Q-factor will increase firstly and then decrease with the increase of pre-strain.The reinforcing effects in the small strain are waning at a high temperature,until the stability of incommensurate DWCNTs oscillators is damaged.