Thermal protection tile structures of shuttlecraft with different external load-carrying elements

Abstract

Thermal protection tile structures, made from heat-resistant materials, are widely applied for protection of space vehicle bodies. Carbon-carbon composite materials, high-temperature metal alloys and structural ceramics can be used as high-temperature heat-resistant materials for manufacturing thermal protection structure tiles. The presented work gives calculation-theoretical assessment of strength properties of combined tiles of thermal protection structure of returnable space vehicles, having a metal external load-carrying element and body from carbon-carbon composite material, as well as tiles from carbon-carbon and ceramic materials. The advantages and disadvantages of each of the studied thermal protection tile systems are considered. Strength analysis is used to determine the dimensions of load-carrying elements for bodies of thermal protection structures, meeting the requirements of strength, stability and resistance to flutter, and weight of each structure. It is found that thermal protection tiles with a body from carbon-carbon composite materials and tiles with an external three layer honeycomb panel from YuIPM-1200 alloy have the best weight and strength characteristics. Tiles based on quartz fibers were used in returnable Space Shuttle and Buran vehicles-aircraft for thermal protection of sections, heated up to 1200 °C. A serious drawback of quartz ceramic tiles is their extreme brittleness and low strength, as well as permanent joint of tile thermal protection with airframe skin. More attractive is the concept of removable thermal protection tile structures with the body of resistant materials and internal thermal insulation. Such a structure ensures a more reliable fastening of thermal protection tiles by mechanical means and convenience of their interflight maintenance.Carbon-carbon composite materials (CCCM), heat-resistant metal alloys and structural ceramics can be used as high-temperature heat-resistant material of tiles of thermal protection structure (TPS). TPSs, the surface density of which does not exceed 10 kg/m 2 , are acceptable [1]. Each of heat-resistant materials has its advantages and disadvantages. Metal advantages include the fact that their production is highly standardized and their quality is guaranteed within narrow tolerances. Here extremely important is the fact that extensive experience of transfer of metal sample testing results to full-scale structure parts has been accumulated. The main heat-resistant materials applied for operation in high-temperature structures, are iron-and nickelbased alloys. The main disadvantages of metals are their high specific weight and insufficient corrosion resistance at working temperatures.Ceramic materials are essentially superior to metals and alloys by many service parameters (thermal stability, hardness, corrosion resistance, density, accessibility and low cost of raw materials). The main problems arising at selection of ceramics for TPS tiles are its inherent brittleness and possibility of catastrophic failure because of development o...