仿生石墨烯/金属纳米层状复合材料的强韧化机理研究

Bio-inspired graphene/metal nano-layered composite materials have a broad application prospect in aerospace, automotive and nuclear industry. Understanding the mechanical properties of the material and the toughening mechanisms of the composite is the foundation of design, optimization and application of this composite. But the current research of this composite material is still in the initial stage, especially the mechanical behaviors and the related physical mechanisms are not clear yet. This project aims to establish the strength criterion of composite material with combination of fracture theory and dislocation theory. In addition, shear lag theory is adopted and developed to describe the typical failure modes of the composite. With the combination of molecular dynamics and finite element method, the strengthening and toughening mechanisms of the nano-layered composite could be disclosed. This project focuses on the effects of graphene size, graphene orientation and interface strength parameters on the mechanical properties of nanocomposites and the influence of the failure mode, analyzing of the competition mechanism between the initiation of dislocation motion and crack nucleation in the nano-layered composites, revealing the physical mechanism of the strengthening and toughening mechanisms in the composites. The results are expected to provide a theoretical basis for the design and optimization of graphene/metal nanocomposites.

仿生石墨烯/金属纳米层状复合材料在航空航天、汽车和核工业等领域有着广阔的应用前景，认识材料的力学性能并理解其强韧化机制是该复合材料设计、优化和应用的基础。但目前对于该复合材料的研究还处于起步阶段，尤其是与之力学行为相关的物理机制尚不清楚。本项目拟结合断裂理论和位错理论初步建立该复合材料的强度判据，基于剪滞理论建立描述材料典型失效模式的力学模型，结合分子动力学和有限元法揭示层状复合材料的强韧化机理。本项目着重关注石墨烯的尺寸、取向和界面结合强度等参数和对纳米复合材料力学性能以及失效模式的影响规律，分析石墨烯/金属纳米层状复合材料中位错运动与裂纹萌生之间的竞争机制，揭示石墨烯/金属纳米层状复合材料失效模式转换的机理。研究结果可望为设计和优化仿生石墨烯/金属纳米层状复合材料提供理论依据。

通过模仿珍珠母的“砖-泥”结构，可望制备出高性能的人工复合材料。仿生石墨烯/金属纳米层状复合材料已经展现出了超强的力学性能，在航空航天、汽车和核工业等领域有着广阔的应用前景。认识新型材料的力学行为并理解其强韧化机制是复合材料设计、优化和应用的基础。本项目针对石墨烯增强单晶金属和石墨烯增强多晶金属纳米复合材料，基于剪滞理论建立了描述复合材料典型失效模式的力学模型，并结合分子动力学揭示层状复合材料的强-韧化机理。通过建立石墨烯拔出力学模型，获得了界面剪切应力沿石墨烯的分布规律，得到了拔出速率、界面强度等因素与最大界面剪切应力、相对滑移距离的定量关系，确定了石墨烯拔出和拔断两种典型失效模式及其转化的关键控制参数。发现石墨烯的失效模式和最大界面拔出应力明显依赖于界面强度，在石墨烯的尺寸一定时，界面强度存在一个使石墨烯的失效模式在拔出与拔断之间相互转化的临界值。结论理论分析和数值模拟，详细表征了墨烯的尺寸、取向和界面结合强度等参数和对纳米复合材料力学性能以及失效模式的影响规律，分析了石墨烯/金属纳米层状复合材料中位错运动与裂纹萌生之间的竞争机制，揭示了石墨烯/金属纳米层状复合材料失效模式转换的机理。研究结果可望为仿生石墨烯/金属纳米层状复合材料的设计和优化提供理论依据。