Study On Mechanics Of Peeling Carbon Nanotube From The Surface Of Carbonfiber By Molecular Simulation

Carbon fiber reinforced epoxy composite is widely used in aerospace field, which has the characters such as high specific strength,high specific modulus,thermostability and corrosion resisting. But this kind of composite can not transfer load due to the low wettability between the fiber and the epoxy which lead to crack. It has been effectively improved, after grafting carbon nanotube to the fiber, that the wettability and the effect of the mechanical inter-lock between the fiber and the matrix. By this method,the shear strength is also significantly improved. The main failure mode of this kind of hierarchical composite is the pull-out of carbon nanotube from epoxy and the peeling from carbon fiber. So far, many studies on the mechanics of pull-out have been carried out by experiments, modeling and molecular simulation. However, studies on the mechanics of peeling are still in initial stage. In order to deeply uncover the mechanics of peeling, studies on details of this mechanics are carried out by the method of molecular simulation.Studies are carried out on influences by velocity of peeling and chirality. The results indicate that behavior of carbon nanotube is slightly influnced in the region between0.01A/ps and0.10A/ps. And that peeling behavior of the carbon nanotube is also slightly influnced by chiarlity.Studies are carried out on influence by the ratio of the length and diameter of carbon nanotube. Carbon nanotube can be viewed as rigid rod which is peeled from the surface of carbon fiber when the value of this ratio is small than4.9which is named as critical ratio, and can be viewed as soft rope when this ratio is bigger than4.9. For the DWCNT, the critical ration is5.89which indicate that increase in the number of the walls can improve the rigidity of carbon nanotube.Studies are carried on influences by radial deformation and chemical connection between carbon nanotube and carbon fiber. The results indicate that bigger diameter of carbon nanotube can lead to more intensive interaction which results in maximum peeling force. And the maximum peeling force can be greatly improved by the chemical connection between the nanotube and the fiber.