Abstract： The fracture parameters of graphene are very important to graphene devices. But the relative research is still in the primary stage. In this paper, the tensile fracture process of pre-cracked armchair graphene is simulated by molecular dynamics software - LAMMPS. Firstly, the energy release rate and the stress intensity factor of graphene are calculated by continuum theory and molecular dynamics calculation. It is found that the energy release rate of graphene GIC is 10.11 J/m2 and the stress intensity factor KIC is 3.33MPam^1/2. Further more，a new model based on continuum theory and molecular dynamics is proposed to accurately compute the crack speed in graphene. The factors, including initial crack length and strain loading rate, that affect the crack speed of graphene are discussed. The results show that the crack initiation length and strain loading rate affect the crack speed to a certain degree. Before reaching the limit crack speed, the shorter the initial crack length is, the higher the crack speed is. But with the increasing of the initial crack length, the crack speed is insensitivity to the initial crack length. On the other hand, the higher the strain loading rate, the higher the crack speed is. Besides, the influence relationship on crack speed between initial crack length and strain loading rate is preliminarily discussed. The results show that the influence of initial crack length and strain loading rate on crack speed is related to some extent. With the increasing of strain loading rate, the sensitivity of crack speed to the initial crack length decreases. Based on the previous findings and discussion, this study finally comes to an objective analysis of the limit crack speed. The limit crack speed is 8350 m/s. The conclusions are expected to provide some reference for the practical design and application of graphene devices.
2018, Vol. 39 
