Three-Dimensional Finite Element Ablative Thermal Response and Design of Thermal Protection Systems

Abstract

A finite element ablation and thermal response program for the simulation of three-dimensional transient thermostructural analysis has been developed. The three-dimensional governing differential equations and finite element formulation are summarized. A novel probabilistic design methodology for thermal protection systems has been developed. The design methodology is an eight step process beginning with a parameter sensitivity study and is followed by a deterministic analysis whereby an optimum design can determined. The design process concludes with a Monte Carlo simulation where the probabilities of exceeding design specifications are estimated. The design methodology is demonstrated by applying the methodology to the carbon phenolic compression pads of the Crew Exploration Vehicle. The maximum allowed values of bondline temperature and tensile stress are used as the design specifications in this study. Using the design methodology, the probability of exceeding these design specifications was shown to be low and within an acceptable range.