# 以缺陷石墨烯撕裂性能微观机理提升材料力学实验的内涵Enhancing the Connotation of Material Mechanics Experiment by Microscopic Mechanism of Defect Graphene Tearing Performance

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The measurement of the mechanical properties of materials is a basic skill which is necessary for materials, mechanical and civil engineering students, but the mechanism of material stress is not fully demonstrated in the material mechanics experiments. In the process of experiment, the atomic displacement and force change of the material tearing process can be visually displayed at the atomic and molecular level to further explore the connotation and microscopic scale perfor-mance of the material mechanics experiment to improve students’ in-depth understanding of the microscopic mechanism of material mechanics. This paper designs a tear simulation experiment based on typical two-dimensional material defect graphene of molecular dynamics. Molecular dy-namics simulation of the mechanical properties and deformation mechanism of perfect single-layer sawtooth and armchair-type graphene tears with single-atomic vacancy defects and diatomic vacancy defects was carried out by molecular dynamics. Through the visual demonstration of atomic displacement and force during the stretching process, the teaching quality of material mechanics can be improved, and students’ deeper understanding of the causes of mechanics can be enhanced.

1. 引言

2. 计算方法及物理模型

${E}_{b}=\frac{1}{2}\underset{i,j}{\overset{N}{\sum }}\text{ }\text{ }{V}_{ij}^{tot}=\frac{1}{2}\underset{i,j}{\overset{N}{\sum }}\left({f}_{c,ij}{V}_{ij}^{SR}+{S}_{ij}{V}_{ij}^{LR}\right)$

${V}_{ij}^{SR}={V}_{R}\left({r}_{ij}\right)-{B}_{ij}{V}_{A}\left({r}_{ij}\right)$

${S}_{ij}=1-{f}_{c,ij}$

${V}_{R}$${V}_{A}$ 分别表示原子i和原子j之间的排斥力和吸引力，作用力类型主要取决于原子间距， ${B}_{ij}$ 表示键序。

${f}_{c,ij}$ 是截断函数，随距离 ${r}_{ij}$ 的增加从1衰减到0，表示原子i与其最近邻原子间的相互作用。

3. 计算结果及分析

3.1. 空位缺陷对石墨烯撕裂力学性能的影响

Figure 1. Physical model of single-layer graphene film. (a) serrated type; (b) armchair type

Figure 2. Schematic of the vacancy defects in single-layer graphene films. (a) single-atom vacancy defect; (b) double-atom vacancy defect I; (c) double-atom vacancy defect II

—应变关系曲线如图3所示，由图可以看出，当锯齿型石墨烯应变量小于1.25%时，石墨烯应力随应变呈线性增长，石墨烯处于弹性变形，应变消失后并不影响石墨烯的结构；当应变量在1.25%~2.5%的范围内时，石墨烯应力处于屈服阶段，此时应变在很小的范围内波动，但应力却不断增大；当应变量超过2.5%之后，石墨烯应力处于强化阶段，石墨烯同时具有弹性变形和因为断裂而产生的塑性变形，但是在应变量增大的过程中，弹性变形逐渐消失，只留下塑性变形。锯齿型石墨烯缺陷的存在对其断裂时应变的影响不大，但它使断裂最大强度明显小于完美锯齿型石墨烯的最大强度。扶手椅型石墨烯的应力—应变曲线趋势与锯齿型石墨烯的大体一致，但是在扶手椅型石墨烯的强化阶段出现了锯齿型石墨烯所没有的应变量在增加，应力却减小的“缩颈”现象结合表1可知。

Figure 3. Stress-strain curves of serrated and armchair-type single-layer graphene films with vacancy defects. (a) serrated type; (b) armchair type

Table 1. Effect of vacancy defects on the tearing mechanical properties of single layer graphene films (unit: Stress: GPa Strain: %)

3.2. 空位缺陷对石墨烯变形的影响

Figure 4. Local atomic structure of tearing perfect single-layer graphene films. (a) serrated type; (b) armchair type

3.3. 温度对石墨烯薄膜的影响

3.4. 撕裂时石墨烯不同原子受力

Figure 5. Local atomic structure of tearing vacancy defects single-layer graphene films. (a) serrated type with single-atom defect; (b) armchair type with single-atom defect; (c) serrated type with double-atom vacancy defect; (d) armchair type with double-atom vacancy defect

Figure 6. Tearing stress-temperature curves of serrated and armchair-type perfect graphene films

Figure 7. Schematic of the direction of force in tearing of two-atoms vacancy defects type II single layer graphene film

4. 结论

NOTES

*通讯作者。

 [1] 任芳, 朱光明, 任鹏刚. 纳米石墨烯复合材料的制备及应用研究进展[J]. 复合材料学报, 2014, 31(2): 263-272. [2] 高艳, 陈红征, 等. 石墨烯材料的功能化及其在聚合物太阳能电池中的应用[D]: [博士学位论文]. 杭州: 浙江大学, 2012. [3] Varghese, S.S., Lonkar, S., Singh, K.K., Swaminathan, S. and Abdala, A. (2015) Recent Advances in Graphene Based Gas Sensors. Sensors and Actuators B-Chemical, 218, 160-183. https://doi.org/10.1016/j.snb.2015.04.062 [4] 钟轶良, 莫再勇, 杨莉君, 廖世军. 改性石墨烯用作燃料电池阴极催化剂[J]. 化学进展, 2013, 25(5): 717-725. [5] Hua, J., Zhang, Y.H. and Wu, X.X. (2016) Vibration Analysis of Detective Graphene Based on the Molecular Structural Mechanics Method. International Journal of Computational Materials Science and Engineering, 5, Article ID: 1650002. https://doi.org/10.1142/S2047684116500020 [6] Hua, J., Liu, Y. and Hou, Y. (2016) Study on Irradiation Repair of Graphene with a Crack. International Journal of Computational Materials Science and Engineering, 5, Article ID: 1650011. https://doi.org/10.1142/S2047684116500111 [7] 曹宇臣, 郭鸣明. 石墨烯材料及其应用[J]. 石油化工, 2016, 45(10): 1149-1159. [8] Geim, A.K. and Novoselov, K.S. (2007) The Rise of Graphene. Nature Materials, 6, 183-191. https://doi.org/10.1038/nmat1849 [9] Novoselov, K.S., Geim, A.K., Morozov, S.V., et al. (2004) Electric Field Effect in Atomically Thin Carbon Films. Science, 306, 666-669. https://doi.org/10.1126/science.1102896 [10] Hashimoto, A., Suenaga, K., Gloter, A., et al. (2004) Directevidence for Atomic Defects in Graphene Layers. Nature, 430, 870. https://doi.org/10.1038/nature02817 [11] Meyer, J.C., Kisielowski, C., Emi, R., et al. (2008) Direct Imaging of Lattice Atoms and Topological Defects in Graphene Membranes. Nano Letters, 8, 3582. https://doi.org/10.1021/nl801386m [12] 王玉娟, 李志翔, 毕可东, 等. 缺陷对石墨烯摩擦性能影响的分子动力学研究[J]. 摩擦学学报, 2016, 36(5): 599-605. [13] 马聪聪, 曹达鹏. 缺陷石墨烯在气敏传感器和锂离子电池中的应用[D]: [硕士学位论文]. 北京: 北京化工大学, 2013. [14] 姚海峰, 陈元平. 缺陷和边界对石墨烯纳米带热输运性质的影响和调控[D]: [硕士学位论文]. 湘潭: 湘潭大学, 2013. [15] Yang, Z., Liu, G., Qu, Y., et al. (2016) First Principle Study on Adsorbing of Fe on N Doping Carbon Nanorube Rings. Chinese Journal of Computational Physics, 33, 374. [16] Wang, W., Gao, J., Zhang, T., et al. (2015) Performance of Asymmetric Linear Doping Tripe-Material-Gate GNRFETs. Chinese Journal of Computational Physics, 32, 115-126. [17] Zhou, S., Liu, G., Jiang, Y. and Song, Y.Y. (2016) Adsorbing of Magnesium on Phosphorus-Doping Single-Walled Silicon Nanotubes: First-Principles Study. Chinese Journal of Computational Physics, 33, 554. [18] 谭新君, 等. 石墨烯薄膜杨氏模量的分子动力学研究[D]: [硕士学位论文]. 湘潭: 湘潭大学, 2011. [19] 张霖, 赵宏伟, 杨倚寒, 等. 单层石墨烯薄膜材料纳米压痕过程的分子动力学分析[J]. 吉林大学学报(工学版), 2013, 43(6): 1558-1565. [20] Los, J.H. and Fasolino, A. (2003) Intrinsic Long-Range Bond-Order Potential for Carbon: Performance in Monte Carlo Simulations of Graphitization. Physical Review B, 68, Article ID: 024107. [21] Plimpton, S. (1995) Fast Parallel Algorithms for Short-Range Molecular Dynamics. Journal of Computational Physics, 117, 1-19. https://doi.org/10.1006/jcph.1995.1039 [22] Stukowski, A. (2010) Visualization and Analysis of Atomistic Simulation Data with OVITO—The Open Visualization Tool. Modelling & Simulation in Materials Science & Engineering, 18, Article ID: 015012. [23] Hoover, W.G. (1986) Constant-Pressure Equations of Motion. Physical Review A, 34, 2499. https://doi.org/10.1103/PhysRevA.34.2499 [24] Melchionna, S., Ciccotti, G. and Holian, B.L. (1993) Hoover NPT Dynamics for Systems Varying in Shape and Size. Molecular Physics, 78, 533-544. https://doi.org/10.1080/00268979300100371