石墨烯拉伸力学性能温度相关性的数值模拟

采用Tersoff势对扶手椅型(Armchair)和锯齿型(Zigzag)单层石墨烯薄膜在不同热力学温度下(0～3 000 K)的单向拉伸力学性能进行了分子动力学模拟,预测了石墨烯薄膜拉伸力学性能对温度的依赖性,并比较了不同温度条件下相同几何尺寸的扶手椅型和锯齿型单层石墨烯薄膜拉伸力学性能的差异.结果表明:石墨烯薄膜的拉伸力学性能和变形机制对温度有强烈的依赖性,2种不同手性的单层石墨烯薄膜的杨氏模量、抗拉强度、拉伸极限应变均随温度的升高而显著减小.石墨烯薄膜力学性能的各向异性也受温度的影响,当温度低于600 K时,扶手椅型石墨烯薄膜的力学性能优于锯齿型的;但当温度超过600 K时,特别是高温时,扶手椅型薄膜的力学性能的优势逐渐减弱,甚至低于锯齿型的.

Numerical Simulation of Temperature Dependence of Tensile Mechanical Properties for Single Graphene Sheet

The tensile mechanical properties of the armchair and zigzag single graphene sheets at different temperatures (0～3 000 K) were investigated based on molecular dynamics simulation with Tersoff bond-order interatomic potential. The dependence of the tensile mechanical properties of the sheets on the temperature was predicted and analyzed. A study was also made of the difference of the tensile mechanical properties between armchair and zigzag sheets at different temperatures. Simulation results indicate that the tensile mechanical properties and deformation mechanism of the sheets are strongly dependent on the temperature. The Young's modulus, tensile strength and limit tensile strain of the two chiral sheets all decrease significantly with the increasing temperature. It is also found that the mechanical anisotropy of the sheets is also affected by the temperature. When the temperature is less than 600K, the mechanical properties of armchair sheets are superior to those of the zigzag ones. However, when the temperature is over 600 K, this superiority diminishes gradually and even turns into inferiority, especially at a high temperature.