Molecular mechanics modeling of deformation and failure of super carbon nanotube networks

A generalized molecular structure mechanics (MSM) model is proposed to investigate the deformation and failure behaviors of super carbon nanotubes (SCNTs) within the quasi-static approximation. The failure mechanism of the SCNTs with Y- and X-type junctions was examined by combining a failure criterion for the breakage of the carbon-carbon bonds in the CNT networks. The carbon-carbon bonds are modeled as elastic bars with equivalent stiffness and break as their elongation ratio reaches only 19%, which means that the broken carbon-carbon bonds are ineffective in terms of the Morse potential function. It is shown that the MSM method, combined with the failure criterion of the carbon-carbon bonds, is a powerful approach to simulate the deformation and failure of both Y junctions and X junctions with different chiralities and sizes. The deformation and failure modes of these junctions which involve rotation, bending and stretching of the CNT arms are predicted using the present model and the effects of various parameters of the junctions on their mechanical behaviors are discussed.