Experimental Investigation Of Tensile And Fatigue Behaviors For The Facesheet Material Of The Thermal Protection System

The thermal protection system facesheet material is the key technology to the safety of hypersonic vehicle, so the research on the thermal protection system facesheet material is very important.The ceramic matrix composites have the advantages of high temperature resistance and good stability, as a result they are the most important thermal protection materials for hypersonic vehicles. In this paper, the mechanical properties of two kinds of ceramic matrix composites(2D C/SiC ceramic composite, mullite fiber-reinforced silica aluminum matrix composites) were researched by MTS material testing machine.Firstly, uniaxial tensile experiments for the specimens of two kinds of material were conducted at room temperature. The data of the two kinds of material were processed, and the stress-strain curves of the tensile test were drawn. Mechanical properties such as elastic modulus and ultimate stress of the materials were carried out. Through the fitting of the stress-strain curve, the law of the material in the process of tensile loading to failure was summarized. Then the fatigue test on the two materials was experimented by up-and-down test. The data such as the life of cyclic loading and load stress level of every specimen were processed, to get fatigue limit of the two materials.Further, the changes of the mechanical properties of different test specimens were analyzed during the experiment. The influence of different loading frequency, loading stress level and other loading conditions on the mechanical properties and the changing trend were researched. The change of the stiffness and the ultimate stress of the materials before, during and after the fatigue test were got. If all the elasticity modulus get from the experiments is conformed to normal distribution was determined.At last, observe the fracture surface of the representative specimen by SEM. Observe the characteristics of fracture surfaces form different fracture form. The same and different characteristics of the fracture surfaces were analyzed. Then, discuss the damage evolution of the material under tensile loading and the damage evolution of the failure.