School of Electrical and Mechanical Engineering, Xidian University, Xi'an 710071, China.
Nanoscale Res Lett. 2014 Jan 22;9(1):41. doi: 10.1186/1556-276X-9-41.
A molecular dynamics study on nanoindentation experiments is carried out for some single-layer rectangular graphene films with four edges clamped. Typical load-displacement curves are obtained, and the effects of various factors including indenter radii, loading speeds, and aspect ratios of the graphene film on the simulation results are discussed. A formula describing the relationship between the load and indentation depth is obtained according to the molecular dynamics simulation results. Young's modulus and the strength of the single-layer graphene film are measured as about 1.0 TPa and 200 GPa, respectively. It is found that the graphene film ruptured in the central point at a critical indentation depth. The deformation mechanisms and dislocation activities are discussed in detail during the loading-unloading-reloading process. It is observed from the simulation results that once the loading speed is larger than the critical loading speed, the maximum force exerted on the graphene film increases and the critical indentation depth decreases with the increase of the loading speed.
采用分子动力学方法对一些边缘固定的单层矩形石墨烯片进行了纳米压痕实验研究。得到了典型的载荷-位移曲线，并讨论了压头半径、加载速度和石墨烯片的纵横比等各种因素对模拟结果的影响。根据分子动力学模拟结果，得到了一个描述载荷与压入深度关系的公式。测量得到单层石墨烯片的杨氏模量和强度约为 1.0 TPa 和 200 GPa。结果发现，石墨烯片在临界压入深度处的中心点发生破裂。在加载-卸载-再加载过程中，详细讨论了变形机制和位错活动。从模拟结果中可以看出，一旦加载速度大于临界加载速度，施加在石墨烯片上的最大力就会增加，而临界压入深度则随加载速度的增加而减小。
