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Composite Materials and Aerospace Construction
Published in Daniel Gay, Composite Materials, 2023
The reentry temperature reaches 1,700°C, or even 2,000°C at the shuttle nose. The thermal protections are of several types, depending on areas of the shuttle and the possible reuse of the heat shield: Heat sinks25 associated with insulation.Radiant heat shield (the wall of the vehicle reflects the heat flux it receives).Ablative thermal protective coating. The ablative material undergoes an endothermic degradation by fusion, vaporization, and sublimation. The chemical decomposition absorbs the heat, and the vaporized gases cool the remaining protective layer, thereby decreasing the convective heat flux.
Advances in Fabrication of Functionally Graded Materials
Published in T. S. Srivatsan, T. S. Sudarshan, K. Manigandan, Manufacturing Techniques for Materials, 2018
Because of the smooth and continuous variation of mechanical and thermal properties, FGMs offer less thermal stress, residual stress, and stress concentration. This attribute allows FGMs to perform exceptionally in thermal environments. For example, in the space shuttle, ceramic tiles are used as thermal protection from heat generated during reentry into the earth’s atmosphere. These tiles are laminated to the shuttle’s superstructure and are prone to cracking and debonding at the superstructure/tile interface due to a sudden change in thermal expansion coefficients. In other words, the ceramic tile expands by a different amount compared to the substructure it is protecting. This difference in expansion causes stress concentration at the interface of the tile and superstructure, which results in cracking or debonding (Department of Defense n.d.; Reddy 2004). An FGM consists of ceramic on the outer surface and metal on the inner surface, which eliminates the abrupt transition between the coefficients of thermal expansion and, therefore, offers better stability and thermal/corrosion protection and provides load-carrying capability (Zidi et al. 2014).
Physical and Thermal Behavior
Published in David W. Richerson, William E. Lee, Modern Ceramic Engineering, 2018
David W. Richerson, William E. Lee
Many applications of ceramics are based upon unique physical and thermal properties. Reentry vehicle thermal protection tiles, for example, require ultralightweight, high temperature resistance, high thermal shock resistance, and low conduction of heat. Density and melting temperature are important physical properties. Heat conduction is a thermal property. Thermal shock resistance is a combination of thermal and mechanical properties. This chapter identifies key physical and thermal properties and describes the source of the behavior based on the concepts of atomic bonding, crystal structure, and phase equilibrium learned in Chapters 4 to 6.
Research on the thermal shock simulation of the super high speed aircraft
Published in Mechanics of Advanced Materials and Structures, 2023
Baoliang Liu, Yining Wang, Changqing Li, Zhongshan Tian, Lihua Cheng
By using ABAQUS software in high-speed aircraft UHTC wing tip front parts entity modeling, load simulation aircraft again into the atmosphere when the flange space heat flux density, analyzed the heat transfer simulation, and the conditions for the heat transfer analysis for thermal stress simulation, respectively, it is concluded that the heat flux density distribution nephogram and node temperature distribution in the cloud, The cloud diagram of thermal stress distribution and the diagram of temperature, stress and strain variation with time of the corresponding element, and the stress value of the element in the stress concentration area were extracted. The stress-strain field of UHTC flange components under thermal shock was analyzed by cloud image comparison and data processing. The following conclusions are drawn: Heat transfer analysis and simulation were used to load the reentry atmospheric heat flux, and the maximum temperature was 2373.3 °C after 700s.Through thermal strain analysis, it is concluded that the maximum strain appears at the sharp corner of the front end of the model, which also explains the reason for the stress concentration phenomenon at the front end of the flange.The “zero ablative” characteristic of UHTC thermal protection material was verified by thermal strain analysis.