空心金属微点阵材料高精度成形关键技术研究

In aerospace industry, lighter weight of structures is never enough. The hollow metallic microlattice material, which is fabricated by combined steps of laser additive manufacturing (such as self-propagating photopolymer waveguide, projection microstereolithography and two-photon polymerization direct laser write ), coating and polymer template etching, is a kind of new cellular material with excellent mechanical property. Application of this material will contribute a considerable decrease for the structure weight. Nevertheless, a certain gap between practical and theoretical value of elasticity modulus and strength still exist. Improving shaping accuracy is the key to increase its mechanical properties..In this research, aiming at characteristics of critical structure affecting the mechanical property and the manufacture enhancing shaping accuracy of critical structure, hollow copper microlattice material with regular octahedron unit cell will be studied as an object. Nano-thick-film in-situ tension experiments and hollow microlattice material compression experiments will be performed, and the deformation and failure process will be analyzed. A micromechanical model that can reflect microstructural characteristics veritably will be established to explore the impact rules and mechanism of microstructure and its accuracy on mechanical properties of the hollow metallic microlattice material, and then the certain characteristics of critical microstructure affect the mechanical property of material will be illuminated. The measuring method and characterizing technique of the consistency of the critical microstructure feathers will be developed, and then the influence of the manufacturing process on the consistency of the critical microstructure feathers will be investigated through analyzing the section cuts of the hollow microlattice materials, and finally a set of process will be proposed to increase the consistency of the microstructures and decrease the disperse of the mechanical properties of the hollow microlattice materials. Base on this, the influence rules of laser additive manufacturing process on deformation of specified microstructure will be analyzed, the residual stress and deformation of the hollow microlattice material due to the coating and etching process will be investigated, and finally, a set of techniques to reduce the manufacturing errors will be proposed through modifying the STL model to compensate the manufacturing error and optimizing the coating and etching process to decrease the residual deformation. This research achievements will provide theoretical principle and practical evidence to increase the shaping accuracy and mechanical performance of this kind of hollow microlattice materials.

结构轻量化是航天装备的永恒追求。空心金属微点阵材料综合激光增材制造、涂层工艺和骨架去除工艺制成，性能优越，其应用将大大降低航天结构重量。然而，该材料弹性模量和强度均与其理论值尚有一定差距，而改善成形精度则成为进一步提高其力学性能的关键。.针对影响该材料力学性能的关键微结构特征和提高关键微结构成形精度的方法两个关键问题，以规则八面体单胞空心铜微点阵材料为研究对象，开展纳米薄膜力学性能测试和空心微点阵材料压缩测试。构建可反映真实微结构特征的细观力学模型，揭示微结构及其成形精度对该材料力学性能的影响规律和机理，阐明影响该材料力学性能的关键微结构。发展微结构测试方法和一致性表征技术，分析相同制作工艺流程对不同位置处的关键微结构特征的影响规律，以及不同制作工艺流程对微结构分散性的影响规律，揭示改善空心金属微点阵材料微结构一致性的工艺方法。分析激光增材制造工艺对上述关键微结构制造误差的影响规律，并研究涂层和骨架去除工艺所致残余变形，发展一套通过微调输入模型补偿制造误差和优化工艺降低残余变形的高精度成形方法，为空心微点阵材料力学性能的提高奠定理论基础和实践依据。

结构轻量化是航空航天装备的永恒追求。空心微点阵材料是一种具有超轻、超刚、超强、超吸能等优越力学性能，以及减震降噪、耐热隔热、过滤催化等多功能性的新型超材料，在航空航天和众多领域具有广阔的应用前景。然而，受限于当前的制造技术水平，该材料的力学性能与其理论值尚有差距。研究空心微点阵材料的微结构特征，开发提高其弹性模量和强度的方法，对该材料的研发和应用具有重要意义。因此，在本项目的执行过程中，我们开发了一套制备与表征空心微点阵材料的工艺设备流程，在此基础上通过有限元模拟、与实验、力学理论相结合的方式进一步研究了关键微结构特征及制造精度对其力学性能的影响。为了进一步提升其力学性能，我们制备了基于纳米材料（碳纳米管、石墨烯等）力学性能增强的Ni-P-CNTs/G空心微点阵材料，并分析了碳纳米管和石墨烯纳米材料在镍磷基材中的增强机理。项目开发了的完整的纳米材料增强空心微点阵材工艺料对制备更轻、更强提供了可遵循的流程。基于原位压缩实验和有限元分析揭示了实际的变形机制及其与理论模型的差异，发展了相关理论模型。在项目执行过程中，共计发表文章期刊论文5篇，会议论文3篇，申请专利4项。这些研究成果揭示了影响空心微点阵材料力学性能的尺寸参数和制造差异；也揭示了石墨烯、碳纳米管增强作用于机理；为大规模生产空心微点阵材料提供了进一步可能；更进一步为制备具有更加优良力学性能的新型空心微点阵材料具有指导意义。

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