Design And Material Preparations Of Gradient Connections For Integrated Thermal Protection Systems

Thermal protection system as a key subsystem of hypersonic aircraft, is to force the thermal structure coupling direction of integration. As a typical integrated thermal protection system, corrugated sandwich structure of the web facing heat short circuit and thermal mismatch effects are obvious problems. So how to solve this problem has become one of the key issues in the research of integrated thermal protection. The reason for this problem is the contradiction between bearing and heat insulation function of the connection structure. Around this contradiction, this paper puts forward using gradient transition materials as connection structure material, in order to solve the problem of the above methods. Thesis mainly analyzed and designed the gradient of the web, and the web material gradient experiment preparation and performance analysis.In order to verify the gradient transitional connection structure feasibility to solve the problem of short circuit and hot mismatch, corrugated sandwich was established by the integrated thermal protective thermal coupling. Comparative analysis of the hybrid phenolic resin/ceramic, hybrid polyimide resin/ ceramic types of linear gradient web with single ceramics web of the temperature and stress response under typical thermal load. The results show that the gradient material as the web, can reduce thermal temperature on the back and the thermal stress.Secondly, in order to determine the best form of gradient transition to guide material preparation. Analysis of the thermal protection system on the back of temperature, structure stress distribution under various transitional forms gradient. The results show that the gradient transitional forms have a more significant impact on the structural response. Objective of minimizing the structural stress, material properties in the thickness direction at different positions of the design variables, a gradient transition form optimization method is established. In view of the materials studied in this paper respectively have optimal gradient transition design result.The results based on the finite element model to carry out the preparation and properties of materials. The hybrid phenolic resin material and hybrid polyimide resin material were prepared first. The hybrid materials as precursors using pyrolysis temperature gradients are obtained pyrolysis phenolic resin FGM and polyimide resin FGM. The results showed that the hybrid material phenolic resin and the polyimide resin hybrid materials both have good mechanical properties and thermal stability. Phenolic resin gradient material’s thermal stability is better than polyimide gradient material, both have a relatively poor mechanical properties.