High-temperature mechanical behavior of three-dimensional needled woven composites based on <i>in situ</i> tensile testing and micro-CT characterization

Three-dimensional needled woven composites have attracted considerable attention in aerospace applications owing to their superior mechanical performance and structural stability at elevated temperatures. To accurately assess their high-temperature mechanical behavior, systematic in situ tensile tests were conducted, and an innovative parallelepiped representative volume element model was established to enable a comprehensive numerical investigation. An image-based finite element model was developed using advanced boundary path extraction and computed tomography reconstruction techniques, which was further applied to analyze stress distribution and damage evolution under uniaxial tensile loading at 1000 °C. The results reveal that damage progression exhibits pronounced heterogeneity and directional dependence. Matrix cracking initiates at an early stage and governs the initial mechanical response, followed by a gradual transition where transverse fiber bundles become the primary load-bearing constituents, while longitudinal bundles experience progressive damage accumulation. The numerical predictions agree well with the experimental observations, confirming the reliability and predictive capability of the proposed modeling framework.