Biomimetic Research On Thermal Protection Structure Materials Of Aero-space Plane

This paper first introduced development of reusable thermal protect system(RTPS) of aboard aero-space plane, USA’s mainly, including research and development difficulties of this system, setting of different temperature regions, measures of protection, materials selection, comparison of two generations of RTPS, new ideas and new materials used in X-37 B plane. Based on the above, an attempt was also tried in this paper for finding a technological way of RTPS’ development according to the characteristics and level of our country in the area of aerospace technology. In this way, the related requirements of RTPS were also determined according to the development trend of RTPS’, and the relative research contents and technical route were also arranged.According to the special needs of aero-space plane on the aspects of thermal protection, bio-inspiring ideas were put forward in this paper to design structural models, low temperature type, medium temperature type and high temperature type. After that, appropriate raw materials were chosen for each type model and preparing methods, fiber winding, model compressive bonding, machining, electrical machining, resistance welding, diffusion welding, electrodeposition, fiber knitting, were determined to prepare five types of appropriate samples successfully, whose mechanical and thermal properties were then tested, and relative conclusions are drawn on the base of analysis.According to micro-structure of cybister elytra, elytra-inspiring structure of two-direction square tubes, made of carbon fiber and aramid paper, was put forward. Then the corresponding samples were prepared through combined processes of fiber winding and model compressive bonding. Mechanical tests showed that the compressive specific strength of the sandwich structure was about 83% higher than that of aramid paper honeycomb sandwich structure. Bath experiments displayed excellent insulation ability of this structure material. In addition, mechanical and thermal analysis results of the structure materials all had a good consistency with the test results.After a type of simple and regular porous structure was modeled, line-gridded metals with highly regular structure were prepared in this study through combined process of resistance welding and electrodeposition. Mechanical tests showed that these samples owned concentrated mechanical property value, with much lower dispersion properties than counterpart foam metals. Because of simple and regular structure, mechanical properties of pipe-gridded metals can be predicted by FEM(finite element method) analysis. Line-gridded nickel can obtain intermediate level in strength among all kinds of porous metals made of the same metal and with the same density.Through the improvement of the metal line grating material model, model for pipe gridded was obtained by way of replacing metal lines with metal pipes and pipe-gridded metals with highly regular structure were prepared through machining, electrical machining and diffusion welding. Mechanical tests indicated that, pipe-gridded metals not only maintain concentrated mechanical property value because of their highly regular structure, and that, but also obtained excellent specific strength significantly, 52% higher than that of counterpart line-gridded metals. Similarly, mechanical properties of pipe-gridded metals can also be predicted easily and quickly by FEM analysis. Pipe-gridded nickel can obtain level above the average in strength among all kinds of porous metals made of the same metal and with the same density.Lotus-seedpod-couple structure model was created through the observation, abstract and combination of lotus seedpod’s structure, and porous metal samples were prepared through combined process of machining, resistance welding, and electrodeposition. Mechanical tests result displayed the performance deficiencies of the corresponding samples according to this model, whose defect could be found through FEM analysis and an improvement program was put forward. New samples of improved model were prepared successfully with excepted results through process a little different from the previous. Test data showed that, because of the combination of opening and closed cell characteristics, lotus-seedpod-couple metals possess fine cooling ability as well as excellent mechanical properties, whose specific strengths performed quite well among all kinds of porous metals made of the same metal. In addition, the thermal analysis and test results all showed that the structure had uniform thermal conductivity and excellent heat dissipation performance when one of its faces heated and its interior cavities ventilated.Hexagonal topology method and hole-wall honeycomb unit structure were put forward based on the analysis of the materials, unit structure design and topology method used on the head cone of X-37 B. Unit samples can be manufactured through steps of the gradient design of unit structure, preparation of C-Si C-Al2O3-Na2 Si O3 composites toughened with carbon fiber, preparation parts of C-C composites, parts integration and high temperature sintering. The performance test and FEM analysis all showed that the gradient structure materials obtained excellent comprehensive properties in the aspect of strength, rigidity, heat resistance and insulation.