Tensile fatigue of three-dimensional needling SiO_2f/SiO₂ composites at high temperatures

Three-dimensional needled SiO_2f/SiO₂ composite material is suitable for aircraft radome. Tensile fatigue tests at 600℃ and 800℃ and tensile tests after fatigue loading were carried out to obtain the stress-strain curves of the corresponding tests. By analyzing the shape and size of hysteresis loops under different cycles and the variation of stiffness with cycles, the tensile fatigue mechanical behavior of 3D needled SiO_2f/SiO₂ composites at high temperature was investigated. The results show that temperature has great influence on fatigue stress of 3D needled SiO_2f/SiO₂ composites, and the fatigue properties of the composites are different at 600℃ and 800℃. The modulus of most specimens decreases gradually with the increase of the number of cycles, but the modulus of some specimens fluctuates with the cyclic loading.