ABSTRACT
The special molecular structure of the carbon nanotubes (CNTs) has imparted in them a specialty in their chemical and physical properties. They have caught the attention of the researchers of the past decade for their exceptional properties such as high Young’s modulus, high tensile and compressive strength, extraordinary flexibility and resilience, high electrical and thermal conductivity, and so on. The more understanding of the relationship between the structural order of the nanotubes and their mechanical properties will be deeper, the more will be the progress in the quality of the carbon nanotube based composites and other applications. Again, the electrical properties of the CNTs may be tuned by mechanical deformation. Such properties are of great interest for applications such as sensor or smart materials. The mechanical properties of both the single wall carbon nanotubs (SWCNTs) and multi wall carbon nanotubes (MWCNTs) have been studied which confirmed that the tensile strength of the CNTs is 1000 times greater than that of steel. The in-plane C-C bond in CNTs is strong covalent σ bond. In contrary, there exists a weak π bond out of the plane which acts in between the shells of a multi-walled carbon nanotube or in between different single-walled CNTs in a bundle. The combination of high strength, high stiffness, and high elastic modulus along the axial direction with low density and high aspect ratio of the tubes has imparted in them, excellent mechanical properties such that they may be used as reinforcing fibers in a polymer matrix to prepare low weight, high strength structural composites. As a component of a fiber-filled composite, the exact knowledge of the mechanical characteristics of the CNTs is necessary to tailor them for specific use. However, the proper strength and failure behavior of the material’s can only perfectly be understood by atomistic simulation. In the nano-regime, the continuum mechanics is inadequate and an atomistic description of the system is necessary. Moreover, SWCNT bundles or MWCNTs are often taken as experimental samples and their breaking or the buckling process is very complex phenomena which can be handled by atomistic simulation technique. Here the power of molecular dynamics simulation technique is exploited in investigating the mechanical characteristics of three different types of SWCNTs, their bundles, and MWCNTs to compare their mechanical properties and failure mechanism.
