Thermal–Structural Coupled Analysis and Design of a Reentry Capsule with Ablative Thermal Protection Systems

Reentry capsules are exposed to extreme aerodynamic heating during their return to Earth, experiencing up to 15 MW/m² of heat flux on their surfaces. Therefore, thermal protection system (TPS) that utilize ablative materials capable of effectively dissipating heat through ablation and charring are necessary. In this study, an initial configuration comprising TPS, substructure, and box was designed. Design requirements were established by considering the temperature limitations of the payloads, degradation of the effective properties due to pyrolysis of the TPS, and yield strength of the substructure. Based on the initial configuration, three models were constructed by varying the TPS thickness, and thermal–structural coupled analysis was conducted by considering the reentry trajectory. The thickness that satisfied the thermal design requirements was selected, and the stress results of the substructure were evaluated. The internal geometry was modified to relieve stress concentration and provide an additional thickness margin for unpredictable mechanical ablation. Thus, all design requirements were satisfied, ensuring thermal protection performance and structural safety. The thermal–structural coupled analysis and design procedure proposed in this study were confirmed to ensure the reliable design of reentry vehicles.