单层石墨烯薄膜材料纳米压痕过程的分子动力学解析  

Molecular dynamics simulation of nanoindentation of single-layer graphene sheet

作　　者：张霖[1] 赵宏伟[1] 杨倚寒 马智超[1] 黄虎[1] 马志超[1] 

机构地区：[1]吉林大学机械科学与工程学院,长春130022

出　　处：《吉林大学学报（工学版）》2013年第6期1558-1565,共8页Journal of Jilin University:Engineering and Technology Edition

基　　金：'863'国家高技术研究发展计划项目(2012AA041206);国家重大科学仪器设备开发专项项目(2012YQ030075);国家自然科学基金项目(50905073;51275198;51105163);吉林省科技发展计划重点项目(20110307)

摘　　要：在原子尺度上分析了单层石墨烯的纳米力学性能和变形损伤机理,得到了纳米压痕仿真的载荷-位移曲线;对不同半径金刚石压头、不同半径石墨烯材料、不同温度以及边界条件等因素对石墨烯纳米力学性能的影响分别进行了讨论,并得到了以下结论:当压头压入深度小于临界深度hc时,石墨烯材料发生纯弹性形变;达到hc时,石墨烯薄膜压头下方原子键断裂并产生撕裂破坏;大于hc时,在压头下方区域的原子相对位置不能完全恢复到压入前的位置,这些原子成为石墨烯材料再次加载时的破坏起点。薄膜材料出现裂口后,集中于压头下方的最大应力迅速减小,应力随之发生了均匀化分布。此外,石墨烯材料半径主要影响压痕过程中的临界深度,而对临界载荷、弹性模量和破坏应力的影响不大。温度升高引发石墨烯薄膜材料的弹性模量和破坏极限均出现了一定程度的下降。The nanoindentation of single-layer graphene sheets is simulated using molecular dynamics simulation. The nano-mechanical properties and failure mechanisms of single-layer graphene sheets are investigated at atomic scale. A typical load-displacement curve is obtained and the influences of the radii of indenter and graphene, temperature and different boundary conditions on the simulation results are analyzed. Observation of the deformation process shows that, when the indenter displacement reaches a critical depth, he, the single-layer graphene sheet undergoes plastic ripping damage due to the atomic bond breaking beneath the indenter. Further analysis of the stress distribution on the graphene around the destruction area reveals that, when a gap is generated on the graphene, the maximum stress decreases rapidly and a homogenization distribution occurs. In addition, repeated loading-unloading processes are performed on the graphene sheet. When the penetration depth is less than the critical value, he, the sheet undergoes an entire elastic deformation. However, when penetration depth is larger than he, the deformed hexagon beneath the indenter can not be fully restored to the original state. Easier deformation of graphene may initiate from these bonds, which in turn, results in significant decrease in strength and deformation of the graphene. In addition, the elastic modulus and deformation mechanism of the graphene sheet are strongly dependent on the temperature. The rise of temperature leads to the decrease in the elastic modulus and the failure limit to some extent. Different radii of the single-layer graphene sheets affect the critical penetration depth on nanoindentation. This is due to the homogenization distribution of deformation in a wide range on graphene sheet. But it has a little effect on the elastic modulus and failure stress.

关 键 词：非金属材料力学性能 单层石墨烯薄膜 分子动力学 纳米压痕 应力分布 

分 类 号：TB332[一般工业技术—材料科学与工程]