Mechanical Properties Of Carbon Nanotubes And Influence Analysis Of Size And Temperature

The carbon nanotubes(CNTs)have many good mechanical properties.In this study,the mechanical properties of carbon nanotubes of different type sizes under thermal environment temperature are studied,and some contents are improved and supplemented in order to enrich the theory of mechanical properties of carbon nanotubes.The first direction of research is the study of Young’s modulus of carbon nanotubes.The Young’s modulus of single-walled carbon nanotubes(SWCNTs)at different temperatures was studied by means of molecular structure mechanics and continuum mechanics.In the process of research and derivation,the mechanical constants are improved,the influence of wall thickness is considered,and the influence of wall thickness is expressed by theoretical formula.In this paper,the finite element method is used to establish the model for the double-walled carbon nanotubes.In order to consider the influence of van der Waals force,a nonlinear spring element is developed,and the equivalent Young’s modulus of double-walled carbon nanotubes under the influence of temperature is derived by numerical simulation method.Finally,the Young’s modulus of single-walled carbon nanotubes and double-walled carbon nanotubes are compared and validated with other data.The second direction of the research is the study of the volume modulus of carbon nanotubes under the change of ambient temperature.There are not many literatures for the study on the bulk modulus of carbon nanotubes,especially on the influence of ambient temperature change.In this paper,the volume modulus of single-walled and double-walled carbon nanotubes under ambient temperature change was studied,which enriched the study of the volume modulus of carbon nanotubes under the influence of temperature.The third direction of the research is the thermal buckling analysis of curved carbon nanotubes(CCNTs).In recent years,researchers generally focus on the study of perfect carbon nanotubes,but carbon nanotubes are likely to bend in the production process or when combined with elastic media,so it is particularly important to study the mechanical properties of curved carbon nanotubes.In addition,based on the influence analysis of ambient temperature on the mechanical properties of carbon nanotubes,in this paper,the parameters of ambient temperature change were specially added in the buckling analysis to more comprehensively analyze the thermal buckling characteristics of bending carbon nanotubes.Moreover,Eringen nonlocal elastic theory and stress gradient theory are used to simulate the bending CNTs as Euler-Bernoulli bending beams.The governing equations of the bending motion of CNTs are derived,and the analytical solution of thermal buckling of curved carbon nanotubes was obtained by differential quadrature method.