INVESTIGATION OF THERMOMECHANICAL PROPERTIES OF ABLATIVE THERMAL PROTECTIVE MATERIALS UNDER HIGH TEMPERATURE

摘要

In this paper, according to the analysis of the ablative mechanism of thermal protective materials under elevated temperature, the ablation-phase transformation properties and the thermomechanical behavior of the component materials are investigated by Eshelby equivalent inclusion method. Through the hypothesis of the statistical uniform distribution of the phases consist of solid products of thermodestruction at high temperatures and pores in the materials, the interaction among different phases by complicated internal physicochemical processes in a matrix and fibers is considered. The exact relationship between the micro-structure and the macro-behavior for ablative thermal protective materials are expressed, and the numerical solution are also given. With the help of the model, the following high-temperature phenomena have been described: degradation of elastic moduli of the materials in heating, dependence of heat properties of the materials not only on temperature but also on duration of heating. Comparison of the theoretical and experimental results for typical ablative materials showed that the model allows one to forecast the thermomechanical characteristics of the materials with sufficient accuracy. It will be helpful for the analysis of the composite materials high-temperate structure.