High velocity impact analysis of free-free carbon nanotubes

In the present work, molecular dynamics (MD) simulations are used to investigate the impact behavior of single-walled carbon nanotubes (SWCNTs) with free boundary conditions in two directions, i.e. vertical and horizontal. To consider the effect of consecutive impacts, the number of carbon nanotubes (CNTs) participated in simulations is chosen from two to five in a row. MD results show that adding the number of impacts increases the magnitude of energy loss in both mentioned directions and reduces the maximum impact force in horizontal cases. In addition, by increasing the velocity of striker CNT from 1 km/s to the maximum value which causes any fracture, the effect of initial velocity on the impact properties and also the ultimate initial velocity for each model are investigated. It is demonstrated that the energy loss and the maximum value of impact force increase as the initial velocity of the striker increases. Also, it is found that the impact strength in the vertical direction is higher than that of the horizontal one, while the horizontal CNTs perform better in the absorption of impact energy. Moreover, for all models, the fracture mechanism of CNTs resulting from the impact process is represented and the procedure of failure is explained.