| Summary: | The temperature dependence of the fracture toughness <i>J<sub>C</sub></i> of a three-dimensional (3D) random fibrous (RF) material, with a porosity of 87% along the through-the-thickness (TTT) direction, was investigated using experiments and the finite element method (FEM) in this study. The temperature considered ranges from 299 to 1273 K. The experimental observations revealed the fracture toughness <i>J<sub>C</sub></i> with crack length-to-width ratios of 0.4 and 0.5, which increased from 47.32 to 328.28 J/m<sup>2</sup> and from 44.92 to 280.09 J/m<sup>2</sup>, respectively, as the temperature increased. Then, a 3D FE model, considering the meso-morphology characteristics of the 3D RF material, was developed to simulate a size-scaled compact tension (CT) specimen with a single edge crack. Using the elastic modulus and the fracture strength of the silica fibers at room temperature, we verified the effectiveness of the FE model, then predicted the fracture strength of the silica fibers and the bonding between the fibers at elevated temperatures. In addition, our developed FE model proved to successfully simulate the fracture toughness <i>J<sub>C</sub></i> from 299 to 1273 K and reveal the deformation mechanism of the 3D RF material at different temperatures.
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