Mechanical Properties Evaluation of Carbon Nanotube Sheets

The use of carbon nanotubes in nanotechnology and leading industries are of extreme important and have many applications. One such application is producing nanotube thin pages called buckypaper. These pages that also known as nanotube sheets have significant physical, chemical, mechanical, thermodynamics and electromagnetic properties such as strength several times more than steel and also density about one seventh of steel. So, manufacturing and modelling of such materials have taken attention of scientists and engineers more than before. However, understanding of the nano mechanics behaviour for nanotube sheet is still in its infancy. This motivates the present research to find faster and simpler methods than before to calculate the mechanical properties of this material by using finite element method. Toward this purpose molecular network of the buckypaper which is consist of ordered arrangement of nanotubes, is modelled as a structure with its atoms as nodes, bonds as 3D-beam elements and Van der Waals forces by the means of nonlinear forces. A computer program was developed to calculate the mechanical properties of buckypapers specially, modulus of elasticity. The program has the ability to create nanotube structures with different chiralities. The nanotubes then arrange together to create a simple ordered network with periodic boundary conditions which is a good resemble for the real buckypaper. Finally, the results are compared with atomic scale models in Molecular Mechanics. The results of simulations have predicted reasonable Young’s moduli for single wall carbon nanotubes comparing to those found in the literature [1]. For single layer and multi layer buckypaper model, higher young moduli values have obtained from simulations in compare with the results reported from experimental testing [2]. The difference is mainly due to the exclusion of factors such as particle impurity, uneven thickness, imperfect alignment, etc. Therefore, these higher values may represent the upper bound young’s moduli for the buckypaper which could be achieved ultimately when their fabrication techniques are continuously improved in the future.

کلیدواژه ها:

Buckypaper ، Finite element ، Mechanical properties ، Molecular Mechanics ، Carbon nanotube sheets