基于分子结构力学的石墨烯力学特性研究

发布时间：2018-06-19 11:44

  本文选题：石墨烯 + 分子结构力学　； 参考：《西安建筑科技大学》2016年硕士论文

【摘要】：石墨烯具有优良的力学、电学、热学特性,自从2004年被发现以来一直被国内外学者广泛研究,其显示出的独特的性质被认为是具有战略意义的新型碳材料。其各项力学性能的研究也是国内外力学学者的研究热点。本文主要基于分子结构力学理论,利用有限元方法对石墨烯的弹性性能和振动特性进行研究。通过分子力学理论中原子间势能与宏观结构力学理论中梁的应变能之间的等价关系,建立了能模拟C-C共价键的圆形截面梁单元。采用分子动力学理论中的Morse势函数模拟C-C键的非线性关系,采用集中质量单元模拟碳原子,建立了石墨烯框架结构连续介质模型,并且利用有限元方法对模型进行计算分析。对于完美的石墨烯,本文分别研究了扶手椅型和锯齿型两种手性的石墨烯,在尺寸方面分别研究了不同长宽比和不同尺寸的石墨烯。对于含缺陷的石墨烯主要研究了含有不同数量空位缺陷、不同尺寸的空洞缺陷以及不同位置和长度的裂纹的石墨烯。基于以上不同类型的石墨烯,分别研究了其弹性性能和振动特性。在弹性性能方面主要研究了杨氏模量和泊松比等弹性性能参数,在振动特性方面主要研究了含基频的前五阶固有频率和各阶振型。经过以上研究主要得出了如下结论,石墨烯的弹性性能具有尺寸相关性和手性相关性,尺寸对石墨烯的振动特性影响比较明显而手性对振动特性的影响比较小。一定数量的单空位缺陷对石墨烯整体结构的稳定性影响较小,对杨氏模量和泊松比的影响基本呈线性关系,对振动特性影响不大。空洞缺陷的尺寸对弹性性能和振动特性都会产生一定的影响。裂纹的方向和长度对石墨烯弹性性能的影响较大,裂纹的长度和位置对石墨烯的振动特性也会产生一定的影响。
[Abstract]:Graphene, which has excellent mechanical, electrical and thermal properties, has been widely studied by domestic and foreign scholars since it was discovered in 2004. Its unique properties are considered to be a new type of carbon material of strategic significance. The research of its mechanical properties is also a hot spot of mechanics scholars at home and abroad. Based on the theory of molecular structural mechanics, the elastic and vibration properties of graphene were studied by finite element method. Based on the equivalent relationship between the potential energy between atoms in molecular mechanics theory and the strain energy of beam in macroscopic structural mechanics theory, a circular section beam element which can simulate C-C covalent bond is established. The nonlinear relation of C-C bond is simulated by Morse potential function in molecular dynamics theory, and carbon atom is simulated by means of lumped mass element. The continuous medium model of graphene frame structure is established, and the finite element method is used to calculate and analyze the model. For the perfect graphene, the chiral graphene of armchair type and serrated type is studied, and the graphene of different aspect ratio and different size is studied in the aspect of dimension. For graphene containing defects, graphene with different number of vacancies, different sizes of cavity defects and cracks of different positions and lengths were studied. Based on the above different types of graphene, the elastic properties and vibration characteristics of graphene were studied. In terms of elastic properties, Young's modulus and Poisson's ratio are studied, and the first five natural frequencies and modes with fundamental frequency are studied. The main conclusions are as follows: the elastic properties of graphene have dimension correlation and chiral correlation. The effect of size on vibration characteristics of graphene is obvious, but chirality has little effect on vibration characteristic of graphene. A certain number of single vacancy defects have little effect on the stability of graphene structure, and have a linear relationship on Young's modulus and Poisson's ratio, but have little effect on the vibration characteristics. The size of cavity defects will have a certain effect on the elastic properties and vibration characteristics. The direction and length of crack have great influence on the elastic properties of graphene, and the length and position of crack will also affect the vibration characteristics of graphene.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O613.71
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本文编号：2039771