Influence of Defects on the Mechanical Performances of Super Carbon Nanotube

Although nanotechnology processes greatly in recent years, defects are still unavoidable in the production of CNTs and relevant structures, which remarkably reduce their theoretical high-performance. In this study, the influence of defects on the mechanical and fracture performances of SCNT, a CNT-based honeycomb structure, are investigated via molecular dynamics simulations. Defects are revealed to reduce the bearing capacities of SCNTs and the reducing degree significantly relies on both the defect position and the SCNT structure. Defects also modify the cracking path of SCNTs and slow down the fracture propagation, especially for zigzag SCNT. Essentially, defects bring force concentration near the defective area, resulting in the local early fracture. Yet the force concentration degrees of the armchair and zigzag SCNTs are affected by different mechanisms. The force concentration degree of armchair SCNT is displacement-controlled, but that of zigzag SCNT is determined by the force redistribution. The underlying reason for controlling the influence of defect is found to be the force transfer mode of the armchair and zigzag SCNT. With the fact that defects widely exit in the CNT-based networks, this investigation could provide valuable information for the practical applications of CNT-based structures.