Numerical evaluation of temperature-dependent mechanical behaviors of needled carbon/carbon composites from 25℃ to 1200℃

In this paper, a three-point bending numerical model incorporating the distribution of needled fibers was proposed to investigate the temperature-dependent mechanical behaviors of needled carbon/carbon composites from room temperature (25 ℃) to 1200 ℃. To simulate damage initiation in different regions, a modified Hashin criterion and a maximum stress criterion, both accounting for temperature effects, were applied to the unidirectional regions (weftless plies and needled fiber regions) and the short-cut fiber ply, respectively. Meanwhile, damage evolution was modeled using an instant stiffness reduction method. The numerical model was validated against experimental results, revealing the fiber fracture caused by the tension in the 0° weftless ply was the main reason for the complete failure of the needled carbon/carbon composites. In addition, porosity was found to significantly reduce the bending strength of the composite. At 1200 °C, the bending strength of the needled carbon/carbon composite decreased by 58.9 % when the porosity increased from 0.07 to 0.17.