【作者】 穆先才；

【导师】 沈海军；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2007， 硕士

【摘要】 本文研究内容分为两个部分,第一部分:航空铝、钛合金板材电子散射性能模拟;第二部分:研究碳富勒烯及其聚合体的力学特性。第一部分:航空铝、钛合金板材电子散射性能模拟由于辐射带、太阳能量粒子事件、银河宇宙线等因素,宇宙空间存在着大量的带电粒子且大部分的能量在百电子伏到数兆电子伏之间。这些带电粒子常会对航空航天器外部材料,内部仪器和人员造成强的辐射损害。因此,模拟宇宙空间环境中中能电子束对航天航空材料的影响研究显得很必要。在本文第一部分中,我们采用Monte Carlo方法,模拟了中能电子束作用下Al、Ti合金板块中的电子散射,研究了背散射电子BSE(Backscattered Electrons)、吸收电子AEs(Absorbed Electrons)的能量、空间分布,能量损失分布以及SEs(Scattered Electrons)的能量沉积。最终获得了一系列与铝、钛合金中能电子散射相关的非常有价值的计算结果。第二部分:研究碳富勒烯及其聚合体的力学特性随着计算机的软硬件和计算技术的长足发展,分子动力学(MD)与量子力学(QM)以及量子-分子动力学(QMD)为研究碳富勒烯力学和电子特性提供了有效的手段,其中L-J(12-6)势和REBO (Reactive empirical bond order)势在碳系统分子动力学研究中得到广泛的应用。在本文的第二部分中,我们首先采用基于REBO势与L-J势的分子动力学方法,完成了对双石墨层作用下C32、C60、C180、C60@C180分子的压缩过程的模拟,讨论了几种富勒烯压缩过程中的变形、能量、压缩载荷等的变化情况;然后,采用REBO势的分子动力学(MD,molecular dynamics)方法,对三种方形C60聚合层以及一种7C60聚合链的拉伸过程进行模拟,进而探讨聚合层内不同缺陷及不同拉伸速率对这些聚合层或链拉伸力学特性的影响。更多还原

【Abstract】 The thesis has two parts, i.e., Part 1: Simulations on electrons scattering in Al,Ti alloy-plies; Part 2: Mechanical characters of fullerene & fullerene polymeric molecules.Part 1: Simulations on electrons scattering in Al,Ti alloy-plies.Due to the radiant belt, solar wind particles and cosmic rays of galaxy, there are abundant electriferous particles in astrospace, whose energy is from hundreds to millions of eV. The electriferous particles can make radiate damage to alloy-plies of exterior-space aircraft, instruments and astronauts inside the space aircraft. So it is very necessary to simulate middle-energy electrons scattering in the aeronautics & astronautics alloys. In the first part of the thesis, Monte Carlo simulations were performed to investigate the energy and space distributions of electrons scattering in the Ti,Al alloy under the action of middle energy electrons(incident electron energy E0≥500KeV). Further the depth and surface distributions of scattering electrons (SEs) and backscattering electrons (BSEs), energy distributions of BSEs and transmission electrons (TEs), and the energy aggradation in the alloy plies were analyzed. Finally, we get a series of valuable results about electrons scattering in the Ti,Al alloy under the action of middle energy electrons.Part 2: Study on mechanical characters of fullerene & fullerene polymeric.With the improvement of computer software and hardware as well calculation technique, Molecular dynamics(MD),Quantum dynamics(QD) methods have been widely used to study the mechanical & electronic characters of carton fullerenes. Otherwise, the L-J (12-6) potential and the REBO potential are specially used in studying carton systems. first,by the REBO and L-J potential based MD method, the compressive properties of C32, C60, C180 and C60@C180 fullerene molecules under the action of double graphite layers were investigated. According to the obtained results. Second,the REBO potential based MD method was applied to simulate the tension and fracture of the C60 fullerene polymeric layers with no defect, single-edge and center defect, as well as the 7C60 fullerene polymeric chain,respectively. The effects of different defect and tensile velocity on the fracture behaviors and tensile mechanical properties of the C60 fullerene polymeric layers/chain were discussed.更多还原