Design Assessment of Metallic Thermal Protection System for Reentry Vehicles: Thermomechanical and Impact Properties

Abstract

This study presents a design assessment of a metallic thermal protection system (TPS) panel for reentry vehicles made of SUS304 stainless steel under a simulated aerodynamic heating rate of 7.1 W/cm2. This study's TPS panel is made up of an outside sandwich structure, four stand-off brackets, a thermal insulation material, and an interior base frame. The key design issues are the thermomechanical and impact characteristics of the outer sandwich structure. To predict deflections caused by thermal gradients and to estimate initial critical peak loads caused by low-velocity impactors, an analytical method and numerical method are developed. Several design parameters such as maximum deflection, maximum initial peak load, and weight balancing are used to optimize the sandwich structure for the TPS panel. The TPS panel is then manufactured for testing in thermal cycles. Thermomechanical behaviors of the TPS panel are investigated experimentally and numerically. The results indicate that the analytical model agrees well with the numerical model and can thus be used to estimate the sandwich structure’s deflection and initial peak load for the TPS design. The numerical simulation and experimental results of temperature responses and panel deformations are compared. In addition, after 10 simulated flight missions, the panel is evaluated for any possible damages. The analytical method is a good approach to developing TPS panels; the experimental method demonstrates the feasibility of the proposed design of the TPS panel made of SUS304 stainless steel under such a heating rate.