Study Of The Mechanical Properties Of Carbon Nanocones With Vacancy Defects Using Molecular Dynamics Simulation

Carbon nanomaterials such as fullerenes,nanotubes,graphene and carbon nanocones are known by their low density,high strength,high thermal conductivity,high electrical conductivity and high specific surface ratio.Based on these advanced properties,carbon nanomaterials have been applied extensively in many engineering disciplines.However,it is an inevitable fact that these substances suffer from various defects including point defects,line defects and surface defects under laboratory and industry preparation conditions.The point defects are most common among the aforementioned defects and a representative type is the vacancy defect.Recent studies show that vacancy defects have significant influences on the mechanical properties of carbon nanomaterials.Due to improvement in production techniques for carbon nanotubes and graphene,researchers and engineers have gained comprehensive and in depth understanding of carbon nanotubes and graphene in past decades.This is then followed by detailed research on carbon nanocone recently.At present,domestic and international studeis on the mechanical properties of carbon nanocone are still rare,especially the articles about mechanical properties of carbon nanocone with vacancy defects are few reported.Therefore,the study of the mechanical properties of carbon nanocone with vacancy defects,to some extent,gives a supplement for the study contents of mechanical properties of carbon nanocone with vacancy defects in China,and has a reference role for the application of mechanics of carbon nanocone,such as nanosensor and nanoprobe.At first,considering the affection of cone angle,cone height,type of vacancy defects and different potential energy function to the mechanical properties of carbon nanocone,tensile contrast experiments are done by molecular dynamics simulations.Based on the results of contrast tests,regarding a series of carbon nanocones with zigzag vacancy defects as the research object,and AIREBO as the potential energy function,this paper makes further research on the effect of relevant parameters(size,location,distribution,etc.)on the mechanical properties of carbon nanocone.Relying mainly on tensile mechanical properties,compressive and torsional mechanical properties as subsidiary,the molecular dynamics stimulations study are done comprehensively and systematically to obtain relationship curve between temperature and time,relationship curve between tensile load and tensile strain,configuration evolution,ultimate tensile load,ultimate compressive load,ultimate torsional moment,tensile strain limit,compressive strain limit and torsional angle limit under a variety of conditions of defects.In this paper,the results show as follows:firstly,when the distance between the center of zigzag vacancy defect and the top of nanocone is less than a threshold,the ultimate tensile load and tensile strain limit are decreased sharply and then remain basically unchanged.Secondly,keeping the aforementioned distance constant and increasing the number of zigzag vacancy defects of the same size in the circumferential direction of carbon nanocone will only decrease the ultimate tensile load and tensile strain limit slightly.Keeping the aforementioned distance and the number of vacancy defects constant,the different distribution of vacancy defects in the circumferential direction of carbon nanocone,shows insignificant impact on ultimate tensile load and tensile strain limit.Thirdly,for vacancy defects whose center position is in the half of cone high,the ultimate tensile load and tensile strain limit are gradually decreased to a certain level and then remain basically unchanged.Fourthly,for vacancy defects whose center position is in the half of cone high,with the orientation of vacancy defect being changed from axial direction to transverse direction,ultimate tensile load and tensile strain limit are decreased gradually.Lastly,for the compressive and torsional tests,with the increasement of the number of vacancy defects in the circumferential direction of carbon nanocone,ultimate load and deformation limit will decline and be sharper than tensile tests'.