發(fā)布時間：2018-06-23 11:45

  本文選題：石墨烯 + 納米壓痕��； 參考：《西安建筑科技大學(xué)》2015年碩士論文

【摘要】：通過分子動力學(xué)方法,本文模擬了石墨烯的納米壓痕過程,并對其模擬結(jié)果進行了分析。首先介紹石墨烯這一新型材料的研發(fā)現(xiàn)狀及納米壓痕技術(shù)的發(fā)展背景,其次簡述分子動力學(xué)基本思想及模擬的基本步驟,并對選擇勢函數(shù)及運動方程的求解算法加以陳述�；�于以上理論,建立單層石墨烯納米壓痕模型,用Tersoff勢函數(shù)描述金剛石內(nèi)部原子與石墨烯內(nèi)部原子間的相互作用,用Lennerd-Jones勢描述壓頭原子與石墨烯原子之間的范德華力,用Verlet算法求解原子的運動方程。本文研究了石墨烯在納米壓痕過程中的微觀變形機制,探究了載荷-位移曲線在不同加載條件下的變化規(guī)律,壓頭受力和系統(tǒng)勢能的變化規(guī)律,缺陷石墨烯納米壓痕模擬的微觀變形機制,并對不同缺陷類型的模擬結(jié)果進行對比分析,研究了完美/缺陷石墨烯納米壓痕過程中的溫度效應(yīng)。研究表明,石墨烯臨界載荷與壓頭半徑有密切的關(guān)系:壓頭半徑越大,臨界載荷越大,相應(yīng)的壓入深度也越大;薄膜半徑越大,臨界壓入深度越大,但臨界載荷相差不大。在一定的取值范圍內(nèi),壓頭的加載速率越大,它的臨界載荷越大,相應(yīng)的壓深越小。當(dāng)加載速度大于0.05 nm/ps時,加載速度對壓痕曲線有顯著影響,而當(dāng)加載速度小于該值時,壓痕曲線變化較小。對缺陷石墨烯而言,單/雙空位缺陷距離薄膜中心越近,相應(yīng)的臨界載荷越小;同時,不同雙空位缺陷中石墨烯薄膜的載荷-位移曲線呈現(xiàn)不同的變化規(guī)律。單個SW缺陷基本不影響薄膜的力學(xué)性能和變形破壞機制。溫度對單層石墨烯的載荷-位移曲線有一定的影響。
[Abstract]:The nanocrystalline indentation process of graphene was simulated by molecular dynamics and the simulation results were analyzed. Firstly, the research and development status of graphene, a new material, and the development background of nano-indentation technology are introduced. Secondly, the basic idea of molecular dynamics and the basic steps of simulation are briefly described, and the selection potential function and the algorithm for solving the equation of motion are described. Based on the above theory, a nanometer-indentation model of graphene monolayer is established. The interaction between the atoms in diamond and graphene is described by Tersoff potential function, and the van der Waals force between the die-head atom and graphene atom is described by Lennerd-Jones potential. The Verlet algorithm is used to solve the equation of motion of atoms. In this paper, the microscopic deformation mechanism of graphene in the process of nano-indentation is studied, and the variation law of load-displacement curve under different loading conditions, the changing law of the pressure on the head and the potential energy of the system are discussed. The microscopic deformation mechanism of nano-indentation simulation of graphene defects was studied. The temperature effect in the process of perfect / defective graphene nano-indentation was studied by comparing and analyzing the simulation results of different defect types. The study shows that the critical load of graphene is closely related to the radius of the head: the larger the radius of the head, the greater the critical load, the greater the corresponding depth of indentation, and the greater the radius of film, the greater the critical depth of indentation, but the less the critical load. In a certain range of values, the greater the loading rate of the head, the greater the critical load and the smaller the corresponding depth. When the loading speed is more than 0. 05 nm/ps, the loading speed has a significant effect on the indentation curve, but when the loading speed is less than this value, the indentation curve changes slightly. For graphene defects, the closer the defect center is, the smaller the critical load is. At the same time, the load-displacement curves of graphene thin films with different divacancies show different changes. The mechanical properties and deformation-failure mechanism of the films are not affected by a single SW defect. Temperature has a certain effect on the load-displacement curve of graphene monolayer.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O613.71;TB383.1

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本文編號：2057017