Experimental And Simulation Study On Shear Properties Of Hybrid Ceramic Insulation Tiles In Hybrid Fiber System

Spacecraft will generate intense aerodynamic heating during re-entry into the atmosphere.In order to protect the safety of spacecraft internal equipment,it is necessary to lay thermal insulation material on its surface to block heat transfer to the interior.Rigid ceramic fiber insulation tile is a common insulation material.Generally,except for the special position such as the nose cone and the flange,the sub-high temperature zone of the windward surface of the hypersonic spacecraft is often insulated by ceramic tiles.This special laying position leads to It is subjected to strong shearing during re-entry and service,which is very deadly for intrinsically brittle rigid insulation tiles.In this paper,the shear mechanical properties of ceramic fiber insulation tile are studied by combining experimental research with numerical simulation,and the possible influencing factors are analyzed.First,the intrinsic correlation between sample size and shear performance of a rigid ceramic tile shear test was investigated.The shear mechanical properties of ceramic tile materials with different feature sizes were tested to determine the optimum dimensions for the shear test.The results show that when the size is65?40?10mm,the shearing result is larger than the actual value;when the size is804010mm,the shear strength and modulus can be measured more accurately.Secondly,the decay law of shear performance of rigid ceramic tiles under different moisture conditions is studied.The results show that the shear strength of the rigid ceramic tile material is not sensitive to the moisture environment;while the shear modulus decreases with the increase of relative humidity,when the relative humidity is 60%and 90%,the shear modulus of the material decreases by 27%and39%?Then,using MATLAB finite element analysis software to establish a binary system model containing two kinds of hybrid fibers,the model can reflect the structural characteristics of ceramic fiber heat insulation tile,and use this model to obtain the results which are similar to the experimental data and consistent with the line type,and analyze The shear failure process of rigid ceramic tile materials.The results show that for the Al₂O₃/SiO₂ hybrid fiber binary system,the Al₂O₃ fibers are destroyed first,then the SiO₂ fibers are destroyed,and the failure mode is dominated by the connect fiber damage.Finally,the factors affecting the shear mechanical properties of rigid ceramic tile materials are studied and analyzed from both from macroscopic and microscopic perspectives.Macro factors include fiber composition,material density,porosity,and temperature.Microscopic factors include fiber diameter,diameter dispersion,length,orientation angle distribution,and strength of connect fibers.The simulation results show that with the increase of Al₂O₃ fiber composition,the shear strength decreases first and then increases,and the failure rate of SiO₂ fiber increases,and the shear mechanical properties are positively linearly correlated with fiber density and porosity.The increase of temperature will lead to the decrease of shear mechanical properties of the material,and the higher the content of Al₂O₃ fiber,the better the high temperature resistance of the material;the increase of fiber diameter and the dispersion of fiber diameter will lead to the reduction of shear mechanical properties;the increase of fiber length will cause shearing The mechanical properties first increase and then stabilize;the more discrete the fiber orientation angle,the higher the shear mechanical properties of the material.As the strength of the connect fibers increases,the shear mechanical properties of the material first increase and then tend to a constant value.