High-temperature environment and composite materials

Abstract

The problem of simulating the thermomechanical behavior of composites under high temperatures is complex because it straddles many fields: thermal physics, thermal chemistry, solid mechanics, etc. Since concepts such as thermodecomposition and ablation are new to mechanicians calculating microstresses in composites, we define the principal ideas of physico-chemical transformations in this chapter. A schematic classification of the most wide-spread types of high-temperature effects on composite structures is given, and their principal types (aerodynamical heating, gas-dynamical heating, heating in energetic devices, action of a fire and technological heating) are considered in detail. Furthermore, a classification of ablation processes in composites is suggested, and main types of volumetric ablation (pyrolytic thermodecomposition (TD) and thermo-oxidative decomposition (TOD)) and surface ablation (evaporation, chemical reactions with the surroundings (mainly, combustion), melting and thermomechanical erosion) are defined. In addition, the principal phenomena caused by high-temperature effects in composite materials and composite structures are enumerated, and a physical model of ablative composite is suggested.