Multi-scale modeling: Analysis and design of thermal–mechanical coupling behavior of integrated thermal protection systems

In this study, an integrated thermal protection system was formed by bonding the Carbon/Carbon (C/C) composite thermal insulation layer and carbon foam thermal insulation tile on an aluminum honeycomb sandwich panel according to the functions of each layer of materials, and the thermal–mechanical response was analyzed by experimental tests and numerical simulations. First, infrared lamp facility and arcjet wind tunnel tests were used to check the accuracy of the model and calculate the heat-shielding index. Then, using the aerodynamic heat flow and pressure of the vehicles re-entry process, the temperature field and thermal deformation of the thermal protection system were analyzed according to the thermal–mechanical coupling analysis, and its performance requirements as a vehicles shell were evaluated. Analysis show that the thermomechanical properties of each layer were mismatched due to thermal deformation, resulting in debonding at the interlayer interface, which was also observed in the experiment. In addition, a 1 mm gap in the insulation tile promotes the release of thermal stress and reduces interlayer disbonding. According to the multi-scale model, 10 thermal cycles (corresponding to the flight process) were analyzed, and the failure and damage evolution process of C/C composites at the microscopic level were revealed. The results of thermal cycling show that the microscopic damage started from the interfacial debonding of the fiber/matrix and ended with the connection of the pores through crack propagation in the matrix. This study provides a solution for analyzing the thermal–mechanical response of a thermal protection system and a design solution for improving reusability.