Modelling of the mechanical properties of composite materials at high temperatures .1. Matrix and fibers

This paper is devoted to modelling the thermomechanical behaviour of charring composite materials at high temperatures. A multi-level model with an internal structure of unidirectional composite materials consisting of four structural levels is developed. With the help of this model, structural constitutive relations and expressions connecting elastic modules and strength characteristics of charring matrix and fibres with the properties of their internal phases are derived. Comparison of the model with experimental data for different types of matrices and fibres is conducted. Specific phenomena of the high-temperature behaviour of charring composites at high temperatures are analyzed.