空天飞机热防护结构材料的仿生研究

发布时间：2018-07-17 05:22

【摘要】：本文首先介绍了以美国为主的国外空天飞机可重复使用热防护系统(Reusable Thermal Protection System,RTPS)的发展概况,包括该系统研究与开发的难点、温度区域的划分、防护的措施、材料的选用、两代RTPS的对比以及X-37B采用的新理念、新材料等。在此基础上,根据我国空天技术的特点和水平,探寻我国RTPS技术的发展模式。据此,本研究结合该系统发展的趋势,归纳出RTPS的相关需求,并来确定本课题的研究内容和技术路线。根据空天飞机热防护系统的特殊需求,本研究运用仿生的理念,提出了适用于低温、中温和高温条件的多种结构模型。然后,选用适当的原材料,运用纤维缠绕、模压粘结、机械加工、电切削、扩散焊、电沉积、电阻焊、纤维编织等各种工艺手段成功实现了五种样品的制备,通过对它们的力学和热学性能的测试与分析,得出相应的结论。根据东方龙虱鞘翅的微观结构,提出了双向方形管的碳纤维-芳纶纸的仿鞘翅结构。然后,采用纤维缠绕和模压粘结成型的方法制备了相应的样品。力学测试表明,这种夹层结构材料的抗压能力为同密度的芳纶纸蜂窝夹层结构材料的1.83倍。水浴测试结果表明,该结构材料隔热性能优良。此外,该结构材料的力学及热学FEM分析结果与测试结果具有较好的一致性。在建立一种简单规则的多孔结构模型之后,本研究采用电阻焊和电沉积的综合手段实现了金属线条格栅样品的精确制备。力学性能测试结果表明,样品力学性能的数值非常集中,相对于同类型的泡沫金属,它力学性能的离散度明显要小得多。由于结构规则、简单,金属线条格栅材料的力学性能可以通过FEM分析快速预测。在基体材料和密度相同的多孔金属中,镍线条格栅结构的强度属于中等水平。通过改进金属线条格栅,用金属管代替金属线条,设计出规则的金属管制格栅结构的模型,并采用电切削、机械加工和电沉积的综合方法成功实现了样品的制备。力学性能测试结果表明,结构规则的金属管制格栅样品不仅力学性能数值比较集中,而且它的比强度提高显著。与金属线条格栅相比,它的抗压比强度提高了52%。金属管制格栅力学性的FEM分析也同样方便、快捷。在基体材料和密度相同的多孔金属中,镍管格栅材料的强度属于中上水平。通过对莲蓬结构的观察、抽象和组合,建立了莲窝(莲蓬中用于容纳莲子的部分)偶合结构的模型,并采用机械加工、电阻焊和电沉积的综合手段进行了多孔金属样品的制备。力学测试结果表明这种样品在结构和性能上存在一些缺陷,并且存在缺陷的区域可以通过FEM分析确定了,改进方案也可以相应得到。模型结构和加工工艺的略微变化,使得改进型样品也顺利实现了制备,达到了预期的效果。测试数据表明,因为兼有开孔和闭孔结构的优点,所以这种金属结构材料既具有良好的主动散热性,又具有很高的力学性能。在同类型的多孔金属中,该多孔金属比强度处于优等水平。此外,热学分析表明该结构在单面受热、内腔通风时,具有均匀的导热性和优良的主动散热性。通过分析X-37B头锥的材料种类、结构设计和分片布置的特点,提出六边形拓扑方式和孔壁蜂窝单元结构。经过单元结构的梯度设计、C-Si C-Al2O3-Na2Si O3碳纤维增韧复合材料的制备、C-C复合材料零件制备、零件总集成以及高温烧结,实现单元结构样品的制备。力学和热学性能的FEM分析和测试结果均表明,该梯度结构材料在强度、刚度、耐热和隔热方面具有优良的综合性能。
[Abstract]:This paper first introduces the development of Reusable Thermal Protection System (RTPS), which is the main American airspace aircraft, including the difficulties in the research and development of the system, the division of the temperature region, the protection measures, the selection of the materials, the comparison of the two generation of RTPS, the new ideas and new materials adopted by X-37B, and so on. On this basis, according to the characteristics and level of air space technology in China, the development model of RTPS technology in China is explored. According to this, this research combines the trend of the development of the system, sums up the related requirements of the RTPS, and determines the research content and technical route of this subject. A variety of structural models suitable for low temperature, moderate and high temperature conditions were proposed. Then, five samples were successfully prepared by using the appropriate raw materials, using fiber winding, molding bonding, mechanical processing, electrical cutting, diffusion welding, electrodeposition, resistance welding, and fiber weaving, through the mechanical and thermal properties of them. According to the microstructure of the Oriental Dragon lice's Coleoptera, the Coleoptera structure of carbon fiber aramid paper with two direction square tube was put forward. Then, the corresponding samples were prepared by the method of filament winding and molding. The mechanical test showed that the compressive ability of the sandwich structure material was of the same density. 1.83 times the structure of the aramid honeycomb sandwich structure. The water bath test results show that the thermal insulation of the structure is excellent. In addition, the mechanical and thermal FEM analysis results of the structural material are in good agreement with the test results. After the establishment of a simple rule of the porous structure model, this study uses the resistance welding and electrodeposition synthesis. The results of the mechanical performance test show that the mechanical properties of the samples are very concentrated, and the dispersion of the mechanical properties is much smaller than that of the same type of foam metal. The mechanical properties of the metal strip grille materials can be quickly analyzed by FEM because of the structural rules and the simplicity. Speed prediction. In the matrix material and the porous metal with the same density, the strength of the nickel line grid structure is of middle level. By improving the metal line grille and replacing the metal lines with metal tubes, a regular metal control grid structure is designed, and the comprehensive method of electrical cutting, machine processing and electrodeposition is successfully realized. The mechanical properties test results show that the metal control grid samples with structural rules are not only more concentrated in mechanical properties, but also significantly higher in specific strength. Compared with the metal line grille, the compressive strength of the metal control grille increases the FEM analysis of the mechanical properties of 52%. metal control grille. In the porous metal with the same degree, the strength of the nickel tube grid material is in the middle and upper level. By observing, abstracting and combining the structure of the lotus, the model of the coupling structure of the lotus nest (the lotus seed in the lotus seed) is established, and the mechanical processing, resistance welding and electrodeposition are used to make the preparation of the porous metal samples. The test results show that there are some defects in the structure and performance of the sample, and the defect area can be determined by FEM analysis, and the improved scheme can be obtained accordingly. The slight change of the model structure and processing technology makes the improved sample also successfully realized and achieved the expected effect. Test data show that, This metal structural material has both good active heat dissipation and high mechanical properties for both open and closed structure. In the same type of porous metal, the porous metal is at a higher level than the strength. In addition, the thermal analysis shows that the structure has a uniform heat conduction when the structure is heated on one side and the inner cavity is ventilated. By analyzing the materials of the X-37B head cone, the structure design and the characteristics of the partition layout, the hexagonal topology and the honeycomb cell structure of the hole wall are proposed. Through the gradient design of the unit structure, the preparation of the C-Si C-Al2O3-Na2Si O3 carbon fiber toughening composite, the preparation of the C-C composite parts and the overall integration of the parts The FEM analysis and test results of mechanical and thermal properties show that the gradient material has excellent comprehensive properties in strength, stiffness, heat resistance and heat insulation.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：V259;TB17

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