| Single-walled carbon nanotubes have excellent tensile mechanical properties,but their ability to withstand out-of-plane deformation is weak,and large-diameter single-walled carbon nanotubes tend to collapse when subjected to radial deformation.Storing helium into single-walled carbon nanotubes to suppress their collapse is a new idea for the study of collapse control of carbon nanotubes.Under different storage rates,carbon nanotubes will form different configurations after they are collapsed,thus achieving the control of the collapse configuration of carbon nanotubes.The research object of this paper is single-walled carbon nanotubes,molecular dynamics and continuum model for the collapse behavior of singlewalled carbon nanotubes is established.Analytical models of storing helium in single-walled carbon nanotubes were established,including continuous medium models for single-walled carbon nanotubes under continuous thin-shell assumptions,germanium atom models using the closest stacking hypothesis,and interaction models for carbon nanotubes and helium atoms.The analytical model is consistent with the results of molecular dynamics simulation,and the relationship between the configuration parameters of the single-walled carbon nanotubes and the number of helium atoms can be effectively obtained.Defining the storage rate of deuterium atoms in carbon nanotubes,based on the analytical model,the limit of depletion of carbon nanotubes was obtained.The whole process of collapse of the carbon nanotubes was obtained by molecular dynamics simulation.On this basis,carbon nanotubes are filled with helium atoms.The final collapsing configuration of the carbon nanotubes under different storage rates was obtained.The shapes are divided into dumbbell type and peanut type respectively,defining the critical storage rate for the transition from dumbbell type to peanut type and the minimum rate of storage for suppressing the collapse of carbon nanotubes.Considering the van der Waals energy interaction between carbon nanotubes and helium atomic clusters,an analytical model for the collapse behavior of carbon nanotubes is established to obtain a criterion for inhibiting the collapse of carbon nanotubes.The preliminary forecast of the minimum rate of collapse of the collapse was obtained.In order to evaluate the mechanical properties of circular cross-section carbon nanotubes and collapsed carbon nanotubes under different storage rates,two working conditions were designed to analysis the displacement and Mises stress under loading of circular cross-section carbon nanotubes and collapsed carbon nanotubes.After analysis,the mechanical response and failure process of carbon nanotubes under different storage rates were obtained.For the analysis of mechanical properties of collapsed carbon nanotubes,the equivalent stiffness was defined to compare the flexural behavior of carbon nanotubes with different collapse configurations.Helium storage has an enhancement effect on these two kinds of carbon nanotubes.However,its reinforcing mechanism is different.In addition,the temperature control of the behavior of carbon nanotubes was discussed,and the regularity of the heat transport behavior of carbon nanotubes was studied.Helium storage has achieved the control and regulation of large-diameter collapsed single-walled carbon nanotubes.The large-diameter collapsed singlewalled carbon nanotubes,with the increase of the storage rate,have a configuration change and the flexural performance is enhanced.The suppression of collapsing into the carbon nanotubes in the single-walled carbon nanotubes provides a new idea for the material preparation and theoretical research of the large-diameter carbon nanotubes,and has broad application prospects. |
