Centre of Excellence in Design, Robotics and Automation (CEDRA), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
Nanotechnology. 2020 Mar 13;31(11):115708. doi: 10.1088/1361-6528/ab598e. Epub 2019 Nov 20.
In this paper, the mechanical properties of graphene nanosheets are evaluated based on the nonlinear modified Morse model. The interatomic interactions including stretching and bending of the covalent bonds between carbon atoms, are replaced by nonlinear extensional and torsional spring-like elements. The finite element method is implemented to analyze the model under different loading conditions and linear characteristics of the graphene structure including the Young's modulus, surface modulus, shear modulus and Poisson's ratio are evaluated for various geometries and chirality where these properties are shown to be size and aspect ratio dependent. It is also found that when the dimensions of the sheets are greater than a certain threshold, the structure behaves quasi-isotropically and the directional elastic moduli become close to each other by a relative difference no more than 1%. Using the nonlinear stress-strain curve, the yielding point and ultimate stress and strains of the graphene sheet are also evaluated. The results of this study are compared with available experimental data and previous numerical simulations, where good agreement is achieved.
本文基于非线性修正 Morse 模型评估了石墨烯纳米片的力学性能。原子间相互作用，包括碳原子间的共价键的伸缩和弯曲，被非线性拉伸和扭转的弹簧状元件所取代。采用有限元方法对模型在不同加载条件下进行了分析，并针对不同的几何形状和手性评估了石墨烯结构的线性特性，包括杨氏模量、表面模量、剪切模量和泊松比。结果表明，这些特性与尺寸和纵横比有关。还发现，当片材的尺寸大于一定的阈值时，结构表现出准各向同性，并且定向弹性模量彼此接近，相对差异不超过 1%。利用非线性应力-应变曲线，还评估了石墨烯片的屈服点和极限应力和应变。研究结果与现有的实验数据和以前的数值模拟进行了比较，结果吻合良好。
