Research on Improving Fuel Containment Performance of Composite Fuel Tanks

为了充分利用先进复合材料制造运载火箭低温燃料贮箱，本研究项目旨在探讨提高贮箱燃料密封性能的可能性。由于损伤串可以作为燃油泄漏的通道，基于半解析模型，得到了横向裂纹与渗透的定量关系。因此，横向裂纹被认为是泄漏的根本原因。泄漏的防止取决于层压板中是否存在完整或无损伤的层。为了进一步降低油箱的抗渗透性，碳纳米管被用作复合材料树脂的添加剂，既增加了韧性，又降低了树脂的扩散性。研究了不同质量含量的纳米管对树脂力学性能、热学性能和电学性能的影响。环氧树脂和聚醚酰亚胺被用作基础树脂。的贡献的纳米管的刚度改善较大的聚醚酰亚胺树脂，而电导率的增加是较高的环氧树脂，显示复杂的贡献的纳米管的不同properties.The结果本项目的总结为收集的审查文件连同会议论文，发表在过去三年。

In order to construct the cryogenic fuel tanks of launch vehicles by fully utilizing the advanced composite materials, this research project was aimed to look into the possibilities of improving the fuel containment performance of the tanks. As the string of damages could function as the path of fuel leakage, the quantitative relationship between transverse cracks and permeation was obtained based on the semi-analytical model. The transverse cracks were thus found to be the essential cause of the leakage. The prevention of the leakage is dependent on the existence of intact or damage-free plies in the laminate. The formation of transverse cracks in contiguous plies was also thoroughly investigated both experimentally and analytically from this standpoint.To further reduce the robustness of the fuel tanks against permeation, carbon nanotubes were employed as an additive to the resins of the composites, both mechanically increasing the toughness and physically reducing the diffusivity through the resin. The mechanical as well as thermal and electrical properties were looked into for the resins dispersed with nanotubes at various weight content. Epoxy and polyetherimide were used as basic resins. The contribution of the nanotubes to the stiffness improvement was larger for polyetherimide resin, whereas the increase in electrical conductivity was higher for the epoxy, showing the complex contribution of the nanotubes to the different properties.The results of the present project is summarized as the collection of reviewed papers together with the conference papers, published in the past three years.