Study On Tensile,pull And Damping Properties Of Carbon Nanotubes Based On Molecular Dynamics

Carbon nanotubes(CNTs)have been widely used in many fields such as nano electromechanical systems and composite structures due to their excellent mechanical properties and damping properties.In recent years,more and more researchers are concerned about the carbon nanotube size and temperature and other factors affect its mechanical properties and damping performance.In this paper,single-walled carbon nanotubes and multi-walled carbon nanotubes were used to study the factors(such as diameter,length,chirality,number of walls and defects)and temperature on the key mechanical properties of carbon nanotubes(such as Young's modulus and Quality factor).In this paper,the molecular dynamics simulation model of single-walled carbon nanotubes and multi-walled carbon nanotubes is constructed.The models of tensile,drawing and bending of carbon nanotubes are defined by AIREBO potential function,L-J potential and free boundary conditions.With the help of simulation analysis,the relationship between different influencing factors and their mechanical properties and damping performance is analyzed in detail.The following conclusions are obtained:The tensile properties of carbon nanotubes show that the Young's modulus increases with length(or diameter)when the length(or diameter)is small.When the length(or diameter)is large,the Young's modulus is not sensitive to length(Or diameter).The tensile properties of carbon nanotubes decrease with the increase of temperature,and the damage strain and damage stress of armor-shaped carbon nanotubes are the best,and the Young's modulus of sawtooth carbon nanotubes is the highest.The tensile properties of carbon nanotubes decrease with the increase of the number of defects.The number of carbon nanotube walls has little effect on its tensile properties.Multi-walled carbon nanotubes inter-wall drawing study found that the pull performance is not sensitive to length and chirality.The tensile strength of the multi-walled carbon nanotubes increases linearly with the increase of the diameter,and the interface shear stress and surface energy density increase with the increase of diameter and converge to the fixed value.The pull force increases with the number of walls,and when the wall distance is greater than the cutoff radius,the increase in the number of walls has no effect on the pull performance.Carbon nanotubes have found that the Quality factors of carbon nanotubes decrease with increasing frequency under different confined loads and different bending resonant modes,and their Quality factors decrease with increasing temperature.As the diameter of the carbon nanotubes increases,the Quality factor decreases.As the length of carbon nanotubes increases,the Quality factor decreases.The Quality factor of carbon nanotubes decreases with the increase of the number of defects.When the outer diameter of carbon nanotubes is the same,the Quality factor increases with the number of its walls.At the same time,the effects of size and temperature on the Quality factor of carbon nanotubes were verified by thermoelasticity and phonon-phonon damping model.