二维材料具有强度高、柔韧性好、性能可调等优点，在各个领域都发挥着重要的作用。与此同时，二维材料优异的冲击能量耗散能力，使其在冲击防护领域有重要的潜在应用价值。本文主要围绕先进二维材料的冲击动力学行为与高性能设计方法开展相关研究，通过建立微尺度冲击动力学实验技术，发展多尺度数值模拟方法，揭示二维材料的冲击防护性能、能量耗散的宏微观机制，提出具有高防护性能的结构设计方案。主要研究进展包括：

1.针对微米尺度薄膜材料的冲击动力学性能表征，发展了强激光驱动微颗粒高速冲击（Laser-induced particle impact tests, LIPIT）实验技术，建立了真空环境以及高低温（-150^oC~800^oC）的实验环境，实现了极端环境下的微尺度冲击加载方法。同时，通过量纲分析得到了影响颗粒冲击速度的主控无量纲参数，结合有限元模拟（Finite element method, FEM）得到了主控无量纲参数的影响规律。

2.表征了二维材料的基本力学性能，针对石墨炔（Graphdiyne, GDY）这种新型二维材料，首次通过AFM实验获得了其弹性模量（218.50GPa），并分析了实验参数如纳米探针的加载速度和直径对测量结果的影响。实验测得的弹性模量约为分子动力学（Molecular dynamics, MD）模拟计算结果的一半。通过在MD模型中引入不同数量的缺陷和层数，很好地解释了造成两者结果差异的原因。通过MD计算，在原子水平上得到了GDY薄膜的破坏行为以及断键重组的规律，揭示了GDY薄膜优异的柔韧性。

3.通过LIPIT实验测试了GDY及石墨烯（Graphene, GR）薄膜的微尺度冲击动力学行为。发现随着厚度的增加，材料的比吸能快速减小，并观察到了卷曲和多裂尖的失效模式。通过MD对GDY及GR的冲击动力学行为进行了模拟，得到了材料的弹道极限速度，发现超快的弹性波速、锥形波速和较大的变形为材料提供了优异的耗能能力。另外，计算表明单层石墨炔（Single-layer graphdiyne, SLGDY）与单层石墨烯（Single-layer graphene, SLGR）的比吸能接近，表明SLGDY在冲击防护领域的潜在应用价值。同时，发现GDY与GR的失效模式均与冲击速度相关。

4.测量得到了不同厚度碳纳米管（Carbon nanotube, CNT）薄膜的冲击防护性能，发现其比吸能可达到约1.3MJ/kg，比聚合物薄膜和金属薄膜高1~3倍；建立了CNT薄膜冲击的粗粒化分子动力学（Coarse-grained molecular dynamics, CGMD）模型，揭示了CNT在冲击过程中存在断裂、摩擦、振动等多种耗能机制。

5.发展了高性能薄膜材料设计方案。针对GDY与GR，提出了GR/GDY复合薄膜设计思想，充分利用GR高强度和GDY高柔韧性的特点，通过二者的耦合增强耗散效应，提高了材料的冲击防护性能。针对CNT薄膜，提出了交联的方法来加强CNT之间的相互作用、调控材料的吸能模式，实现冲击能量的非局域化耗散，从而实现高防护性能设计，并通过CGMD模拟，给出了优化的结构设计参数。

Two-dimensional (2D) materials play an essential role in various fields due to their high strength, excellent flexibility, and adjustable performance. Meanwhile, the extraordinary impact energy dissipation ability of 2D materials makes them potential application value in the impact protection field. This dissertation reveals the impact protection performance of 2D materials and macro and microscale mechanisms of energy dissipation through the establishment of microscale impact experimental method and multiscale simulation method, focusing on the impact dynamical behavior and design method of high performance of advanced 2D materials, and further put forward the structure design scheme with high protection properties. The main research progress includes:

1. A laser-induced micro-particle impact tests (LIPIT) experimental technology was developed to characterize the dynamical performance of thin-film materials. And a vacuum chamber and high and low temperature (-150^oC~800^oC) experimental environment had been established, which could achieve micro-scale impact in various extreme temperatures. Simultaneously, the main control dimensionless variables that affect the impact velocity of particles was acquired by dimensional analysis. The influence law of these main control dimensionless quantities on particle velocity was obtained by combing the finite element simulation (FEM).

2. The basic mechanical properties of 2D materials were characterized. For the GDY film, the elastic modulus of ~218.50 GPa was obtained through the AFM experiment for the first time. The effects of experimental parameters such as loading speed and diameter of the nano-probe on GDY film's mechanical response were investigated. The elastic modulus obtained by the experiments was about half of that by molecular dynamics (MD) simulations. The introduction of different numbers of defects and the number of layers explained the difference between the two results. The failure behavior of the GDY film and the law of broken bond recombination was obtained at the atomic level, and the excellent toughness of the GDY film was obtained.

3. The microscale dynamical behavior of GDY film and GR film was tested by the LIPIT experiment. With the material thickness increasing, the specific energy absorption decreased. Meanwhile, the failure modes, including curling and multi-crack tip, were observed. Also, the MD simulation was adopted to investigate the dynamical impact performance of GDY and GR, and the ballistic limit of materials was obtained. The MD results revealed that the ultra-fast elastic wave and conical wave speed and the excellent deformation ability of the material contribute to the high energy dissipation. The specific energy absorption of SLGDY is equivalent to SLGR, making SLGDY a prospect for future impact protection materials. The failure modes related to the impact velocity of these two materials were obtained.

4. The dynamic behavior of CNT films with different thicknesses was measured, and the result showed that the specific energy absorption of CNT film can reach about 1.3 MJ/kg, which was 1 to 3 times higher than that of polymer film and metal film. Besides, the coarse-grained molecular dynamics (CGMD) model of CNT film was established and revealed multifarious energy dissipation mechanisms, including fracture, friction, and vibration of the CNT chain.

5. The design scheme of high-performance thin-film materials was developed. The GR/GDY composite film was proposed to effectively combine the high strength of GR and the high toughness of GDY to achieve better impact energy absorption and further improve the impact protection performance of materials. To CNT film, the cross-linked method was put forward to strengthen the interaction of CNTs, regulated the energy absorption mode of CNT film, realized the impact energy dissipation with delocalized mode, and further improve the impact resistance of the crosslinked CNT film. Besides, the optimized structure parameters of CNT film were obtained by CGMD simulations.