大型航天器薄膜结构TPI/PEEK/CNT仿生加强肋的拓扑优化方法及FDM成型机理研究

Deployable membrane structure has many advantages，such as large unfolded area, light quality, small volume, Which can effectively reduce the development cost and launch cost of these spacecraft, and has been widely applied to the flexible solar array, film SAR, large solar sail spacecraft and etc. Tear and wrinkles are the two main failure form of space membrane structure. According to the nature phenomenon that the gradient of strengthening ribs of leaves, feather, and dragonfly wings can effectively increase the structure stiffness and strength, Fused Deposition Molding (FDM) is presented to form TPI/PEEK/CNT bionic strengthening rib (adaptability of thermoplastic composites space) on the membrane structure. The method of finite element modeling and topology optimization method will be researched to provide the theoretical basis of melt extrusion path nonlinear for bionic membrane structure. For studying on the extrusion molding mechanism of TPI/PEEK/CNT, which has the feature of high melting point and poor liquidity, heat transfer theory and system identification method is adopted to establish the nozzle temperature control model. The Non-Newtonian fluid mechanics and Melt Conveying Theory will be used to establish the control model of extrusion pressure. Level set method is used to establish the heat-flow-solid multi-physical coupling model which can describe deposition process of TPI/PEEK/CNT effectively. Finally, through the forming experiment and tearing test of membrane structure bionic rib, the optimization method and forming mechanism described above can be verified.

可展开薄膜结构具有展开面积大、质量轻、收拢体积小等优点，被广泛的应用于薄膜SAR、太阳帆等大型航天器中，可有效降低航天器的研制和发射成本。撕裂和褶皱是空间薄膜结构两种主要失效形式。根据自然界树叶、翅膀等超轻结构中所含有的加强肋具有提高结构刚度和强度的特点，提出采用熔融沉积成型方法在膜结构上成型TPI/PEEK/CNT（空间适应性热塑性复合材料）仿生加强肋。研究仿生膜结构非线性有限元建模方法和拓扑优化方法，为熔融挤出路径提供理论基础；研究熔点高、流动性差的TPI/PEEK/CNT挤出成型机理，采用传热学理论和系统辨识方法建立喷头内外多点加热温度控制模型，采用非牛顿流体力学和熔体输送理论建立挤出压力控制模型，结合水平集合法建立可描述材料沉积固化过程的热-流-固多物理场耦合模型，为成型提供温度、压力控制策略；最后，通过膜结构仿生肋成型实验和抗撕裂、防褶皱测试，验证上述优化方法和成型机理。

可展开薄膜结构具有展开面积大、质量轻、收拢体积小等优点，被广泛的应用于薄膜SAR、太阳帆等大型航天器中，可有效降低航天器的研制和发射成本。撕裂和褶皱是空间薄膜结构两种主要失效形式。根据自然界树叶、翅膀等超轻结构中所含有的加强肋具有提高结构刚度和强度的特点，提出采用熔融沉积成型方法在膜结构上成型TPI/PEEK/CNT（空间适应性热塑性复合材料）仿生加强肋，结合3D打印技术与结构拓扑优化方法，开展薄膜加强肋的成型方法的研究。. 针对空间高低温环境、紫外辐照等需求，选择力学性能优异的聚醚醚酮（Polyetheretherketone，PEEK）为薄膜加强肋材料，选择聚酰亚胺（PI）作为薄膜基体，建立了加强肋拓扑优化数学模型，通过ABAQUS优化模块对薄膜加强肋进行拓扑优化，开发3D打印实验平台，完成了膜仿生加强肋打印实验。最后，研制了专用抗拉能力测试，开展了薄膜的抗撕裂和抗褶皱能力测试。实验结果表明，添加仿生加强肋的薄膜的抗拉能力得到有效提高，其中无裂纹薄膜提高到1.42倍，有裂纹的薄膜提高到3.67倍，而且加强肋有效阻隔了局部裂纹的扩展，提高了航天器薄膜结构在轨可靠运行。. 传统非金属3D打印结构因力学性能差限制了其实际应用。为提高FDM热塑性树脂成型结构件的力学性能，进一步开展了连续碳纤维增强3D打印技术研究，使用熔融浸渍方法研发了连续碳纤维增强PLA丝材，研制了五轴3D打印试验平台，成功打印纤维方向可控的空间曲面结构，经测试，连续纤维增强3D打印结构件的弯曲强度达到800MPa，比纯热塑性树脂打印结构提高了9倍以上，为碳纤维3D打印技术在航天器结构中的应用提供了技术奠定了基础。