石墨烯薄膜拉伸性能的分子动力学模拟

摘要

In this paper, the mechanical properties of monolayer and multilayer graphene sheets under tension in two directions were investigated via molecular dynamics simulation, and the corresponding stress-strain relationships and tensile failure modes were discussed. Then, the size effect and the layer effect on the tensile properties of graphene sheets were analyzed by respectively changing the size of the monolayer graphene sheet and the layer number of the multilayer graphene sheet. The results show that (1) the monolayer graphene sheet, of which the elastic moduli are respectively 1078.02GPa (armchair) and 1041.53GPa (zigzag), is isotropic in the linear stretched e-lastic deformation stage, and its tensile properties are insensitive to size; (2) the multilayer graphene sheet is of a stress-strain relationship similar to that of the monolayer graphene sheet and it shows a more obvious isotropic nature in the linear stretched elastic deformation stage; and (3) the tensile failure of armchair graphene sheets starts from one side and extends inwards along the 45°direction, while that of zigzag graphene sheets starts from both sides and extends inwards in a symmetrical manner.%通过分子动力学模拟,对单层和多层石墨烯薄膜在两个方向上的拉伸力学性能进行了研究,得到了相应的应力-应变关系以及拉伸破坏形态.对单层石墨烯薄膜,研究了薄膜尺寸对其拉伸性能的影响；对多层石墨烯薄膜,研究了薄膜尺寸相同时层数对其拉伸性能的影响.结果表明:单层石墨烯薄膜两个方向的弹性模量分别为1 078.02 GPa(扶手椅型)和1041.53 GPa(锯齿型)；在拉伸线弹性变形阶段,单层石墨烯薄膜是各向同性的,且薄膜尺寸变化对单层石墨烯薄膜拉伸性能的影响不大；多层石墨烯薄膜在拉伸过程中的应力-应变关系与单层石墨烯薄膜类似,且在拉伸线弹性变形阶段表现出比单层石墨烯薄膜更为明显的各向同性；扶手椅型石墨烯薄膜的破坏从一侧边缘开始,并沿45°方向向薄膜内部延伸,锯齿型石墨烯薄膜的破坏从两侧边缘开始,对称地向内部延伸.