Assessment of thermal-mechanical performance with structural efficiency concept on design of lattice-core thermal protection system

A lattice-core thermal protection system (LTPS) integrated thermal insulation and load-bearing capacities was regarded as a promising candidate for future hypersonic vehicles. However, it was found that the concept of thermal insulation efficiency (TIE) is no longer suitable to assess not only the thermal insulation effect of LTPS, but also the load-bearing capacity. Therefore, an innovative concept of structural efficiency is proposed in this paper. The effect of lattice-core inclination angle on the structural efficiency was investigated by numerical simulation approach. Numerical results show that there exists a competition on enhancing the structural efficiency and utilization of bearing material. The inclination angle of 30° is the best choice to obtain the greatest structural efficiency. The maximum stress of C/SiC LTPS is 139 MPa, smaller than the strength of C/SiC composite and locates at the connection between rods and lattice-core sheets. The thickness of C/SiC LTPS is 67.9-69.7 mm, reducing the thickness of multilayer thermal protection system (MTPS) up to 29.3%. The density of the LTPS is 0.15-0.2 g/cm3, linearly increasing with the inclination angle. Structural efficiency provides an evolution index to assess the thermal-mechanical performance of the LTPS.