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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应变率条件下的零温单向拉伸破坏过程进行了分子动力学模拟,预测了石墨烯薄膜拉伸破坏的应变率效应.结果表明,石墨烯薄膜的拉伸力学性能具有应变率相关性.当应变率低于5×109s-1时,两种不同手性的单层石墨烯薄膜的拉伸过程经历了一次强化阶段,杨氏模量均随应变率的增大而减小,抗拉强度对应变率不敏感;当应变率高于5×109s-1时,拉伸过程经历了二次强化,尤其锯齿型的,杨氏模量、抗拉强度和对应的拉伸应变均随应变率的增大而显著增大.在不同的应变率下,石墨烯薄膜具有不同的拉伸破坏变形机制.在低应变率下,石墨烯沿主断裂带断裂破坏,而在高应变率下,形成了缺陷簇,具有非晶化特征.
The Tersoff potential was used to simulate the zero-temperature uniaxial tension failure of armchair and Zigzag single-layer graphene films under different strain rates. The graphene film tensile The results show that the tensile mechanical properties of graphene films have the strain rate dependence.When the strain rate is lower than 5 × 109s-1, the tensile properties of two different chiral monolayer graphene films After a strengthening phase, the Young's modulus decreases with the increase of strain rate, and the tensile strength is not sensitive to strain rate. When the strain rate is higher than 5 × 109 s-1, the tensile strength undergoes secondary strengthening In particular, the Young's modulus, the tensile strength and the corresponding tensile strain increase significantly with the increase of the strain rate.The graphene films have different tensile failure mechanisms under different strain rates At low strain rates, graphene breaks down along the main faults, whereas at high strain rates, degenerated clusters are formed that are amorphized.