冲击载荷下纳米多孔铜材料的力学行为研究

Nanoporous material is a kind of new functional material with optimized functional nano-material and porous structure. The proposed research studies the dynamic mechanical behavior，especially the ones under the impact loading which has an significant influence on the area of material properties and the extension of application. It chooses nanoporous Cu (NPC) as the representative subject investigated. The main focus of the research is measuring mechanical response of NPC under the quasi-static compression and dynamic loading, and analyzing the mechanical behavior under the Hopkinson pressure bar, drop test and high pressure Waterjet. By establishing the nanoscale dynamic mechanical constitutive equations and deformation relations under these different loadings, we discuss the possibility and advantage of energy absorbing applications incorporating with the Molecular Dynamics simulation. The research will reveal the influence of various factors (characteristic size, microstructure topology, strain rate, etc.) on the mechanical properties of NPC, analyze the damage evolution and failure mechanism, improve the simulation models, and ultimately develop a perfect analysis system of the dynamic mechanical properties of nanoporous material. Also, the inner laws between the Waterjet parameters and mechanical state of NPC will be studied. The research may offer a new paradigm in the understanding of nanoporous material and the valuable data and theory utility for their wide range of industry applications.

纳米多孔材料是一种兼具纳米功能和多孔结构双重属性的新型功能材料，探知其动态力学行为，尤其是冲击载荷下的力学响应,对了解材料性能并开拓其应用前景有着重要意义。项目拟通过测试纳米多孔金属铜材料的准静态压缩和动态力学响应，分析其在Hopkinson压杆、跌落测试及水射流冲蚀下的力学行为。并借助建立纳米尺度下的经受不同冲击载荷的多孔材料动态分子动力学仿真模型，探讨该类材料作为高效功能材料应用的可能性和优势。揭示特征尺寸、微结构形态、应变率等因素与力学行为的内在联系，考察其损伤演化及破坏机理，改进仿真模型，完善纳米多孔材料的动态力学响应分析体系,摸索高压水射流工艺参数对纳米多孔金属力学状态的影响规律，以期为工业应用提供有价值的参考和建议。

纳米多孔材料兼具纳米材料和多孔结构双重属性，展现出许多新颖的物理、化学及力学性能，其巨大应用前景已得到共识。拓扑特征，特别是孔隙大小以及孔隙分布的均匀性是决定纳米多孔材料体现优异性能的关键因素。纳米多孔金因其易合成、稳定、代表性强，而成为研究者们关注的重点对象。但随着研究不断深入，技术逐步成熟，本项目选择更贴近工程实际应用、经济性更高的铜介质，作为纳米多孔材料的元素组成，即纳米多孔铜。项目采用放电等离子无压烧结纳米铜、Al-Cu合金放电等离子烧结致密材料去合金化和常规冶炼Al-Cu合金块体材料去合金化三种技术路线来制备纳米多孔铜。系统研究了烧结过程与去合金化各工艺参数对纳米多孔铜成分、微结构及性能的影响规律与内在联系，优化了实验方案并获得最佳工艺参数。. 国内外针对纳米多孔金属力学性能方面的研究已有报道，而鲜有所闻的是多孔金属动态力学特性方面的工作。通过实验制备的纳米多孔金属，很难测量其局部微观力学性能和原位观察局部材料变形行为。基于大量实验和理论分析数据为基础，数值模拟的研究方法能够更生动地表征纳米多孔材料力学性能。本项目工作主要通过有限差分法数值求解Cahn-Hilliard 方程获得具有典型去合金法制备的、棱径约5 nm 的单晶纳米多孔铜模型，将模型应用于分子动力学软件进行单向拉伸行为数值模拟，将材料的力学性能，例如杨氏模量，抗拉强度等参数提取并和经典Gibson 标度律进行比较，分析单晶纳米多孔铜受力变形机理，为后续纳米多晶多孔铜动态力学行为仿真模拟研究提供了借鉴。