Modeling of coupled temperature-displacement-diffusion problem for silica-phenolic composite under high temperature

Volume ablation process of resin-matrix thermoprotective composite is, generally, associated with complex physico-chemical changes, heat and mass transfer processes and irreversible changes of thermomechanical and thermophysical properties. The thermomechanical behavior of resin-matrix thermoprotective material during volume ablation can be analyzed as the coupled temperature-displacement-diffusion problem of porous elastomers under high temperature. Based on the ablative and thermoprotective mechanisms of silica-phenolic composite, the governing equations of the porous elastomers, such as equation of motion of solid phase, gas diffusion equation and energy conservation equation, were established. These governing equations were further modified using finite element method to obtain the element stiffness equation for each element. Additionally, the global stiffness equations were assembled and solved by Gaussian elimination method. The temperature distribution, pore pressure, strain and stress field in plane strain state were calculated when silica-phenolic composite was exposed to a constant radiant heat flux.