Study On Shearing And Peeling Mechanisms Between Carbon Nanotubes Using Molecular Simulation

Carbon nanotube is a one-dimensional structure, it is limited to wide application in the engineering because of its nano size. Creating carbon nanotubes with macroscopic lengths is necessary and important. Carbon nanotube fibers has high strength and toughness, it can be the ideal composite reinforcement. But experimental results show that the strength of carbon nanotube fibers discrete with the length, diameter and wall number of carbon nanotubes varied. It is also found that when the carbon nanotube fibers fail, most of the carbon nanotubes don t wreck, but the interface of the nanotubes failed. Therefore, it is important to study the interfacial mechanisms of the nanotube fibers. There are two types of the carbon nanotubes failed ways: the shear failure and the peeling failure. So far, scientists have studied the internal friction loss in nanotubes by three ways, the continuum theory, the experiment and the molecular simulation. But the research on the interfacial shearing and peeling between the carbon nanotubes is still in initial stage. So studies on the interfacial shearing and peeling mechanisms between carbon nanotubes using molecular simulation are carried out.Studies are carried out on the relaxation time and the velocity of the friction. The results show that the relaxation time of6ps realized efficiency and accuracy, and reach the temperature and energy balance. The results of ten pulling velocities indicate that shearing and peeling behavior of carbon nanotubes is slightly influenced by the velocity, and the velocity share little effect on the maximum friction force, max peeling and stripping force.Studies are carried out on the influence of carbon nanotubes rotation angle and the ratio of the length and diameter. The results show that, the max friction force verifies as rotation angle, length and diameter change. The max friction force increases as long as the carbon nanotube length becomes longer. The max friction force will be the smallest when the diameter of carbon nanotube reaches a number. The research of the influence of H functional groups and its distribution form indicate that, the functional group affect the friction behavior and the max force, thus provides a way to get functional carbon nanotubes.Studies are carried out on the influence factors of the peeling behavior. The results show that the peeling behavior is divided into three types as the nanotube flexible varies. The max peeling force and peeling distance is larger as the carbon nanotubes length becomes longer. When the diameter increases, max force becomes bigger, but the peeling distance is smaller. The research on the influence of the H functional groups indicates that, when the H coating is around30%, the peeling force achieves the max, once H coating overtakes50%, there is little enhancement. The peeling behavior acts absolutely different when the carbon nanotubes contain covalent bonds. It shows that the deformation of the nanotubes becomes large as the nanotubes cracked. It can also see that the max peeling force varies as the coating of covalent bonds, the distribution of the covalent bonds and condition changes.