Thermomechanical And Chemical Coupling Analysis Of Silicone Resin Coated Carbon Fiber Fabric At High Temperatur

Thermal protection material is an important part of thermal protection system.It plays an important role in thermal protection on reentry hypersonic vehicle.As a typical thermal protection material,carbonized ablative thermal protection material has always been the research hotspot of thermal protection system.Therefore,it is necessary to study the ablation thermal response behavior of carbonized ablation thermal protection materials,and then accurately predict the distribution and variation of temperature field.In this paper,the representative silicone resin coated carbon fiber fabric was taken as the research object,the relevant physical parameters of silicone resin coated carbon fiber fabric were tested,the quartz lamp ablation experiment was carried out by simulating the aerodynamic heating process,and the continuous numerical model of thermal response process was established by coupling the three physical fields of heat transfer,solid mechanics and chemistry according to the ablation and anti-heat mechanism of silicone resin.The thermal response process of coated fabric was predicted and optimized,the causes of cavity layer were analyzed,and the generation process of cavity layer was adjusted and optimized by five factors.The main conclusions are as follows:（1）The numerical model of thermal response process of silicone resin coated carbon fiber fabric was established and solved.The simulation data were compared with the experimental data of quartz lamp ablation.It was found that the relative errors between the surface temperature simulation results of front and back of coated fabric and quartz lamp ablation experiment were 3.2%and 6.2%,respectively.（2）Under the heat flow ablation of 400 k W/m²,the silicone resin coated carbon fiber fabric began to pyrolysis at 3 s,and the silicone resin and carbon fiber fabric began to separate.The pyrolysis rate reached the maximum at 10 s,the heat blocking effect reached the peak at 11 s,the heat flow into the interior of the silicone resin decreased by 107335 W/m²,the heat flow into the whole ablation process decreased by 768986W/m²,and the pyrolysis of the silicone resin was completed at 18 s.After 30 s,the silicone resin and carbon fiber fabric hardly separated,and the shape did not change.After 120 s of ablation,the silicone resin surface retreated by 2.03×10^-4 mm.（3）Almost all the force sources of forming cavity layer of silicone resin coated carbon fiber fabric come from thermal stress.Among the many influencing factors of ablation heat protection,the contribution rate of cavity layer was the largest,the specific heat capacity endothermic was the second,and the pyrolytic endothermic and thermal blocking effects were the third.（4）In optimizing the ablation thermal efficiency of silicone resin coated carbon fiber fabric,the transverse thermal expansion coefficient should be increased first,followed by increasing the thickness of the coating,and then to reduce the longitudinal thermal expansion coefficient.Changing the pyrolysis rate and porosity has little effect on the thermal performance.