Mechanical Properties and Fracture Characteristics of Multi‐Structured 2.5D Angle‐Interlock Woven Composites

Five types of 2. 5D angle‐interlock woven preforms were fabricated, namely fiber‐only warp ( FOW ), shallow interlaced curved weft ( SICW ), SICW with reinforcing warp yarns ( SICW ‐ RW ), shallow interlaced straight weft ( SISW ), and SISW with reinforcing warp yarns ( SISW ‐ RW ), to investigate their mechanical performance differences under warp‐direction tensile and four‐point bending loads. Tensile test results indicate that the warp‐reinforced structures significantly enhance the warp‐direction load‐bearing capacity, with the average ultimate load of SICW ‐ RW and SISW ‐ RW increasing by 38.6% and 33.9%, respectively, compared to SICW and SISW . The stress–strain distribution shown by the Digital Image Correlation ( DIC ) technique indicates that the warp‐reinforced design helps reduce the overall strain level. Bending test results show that SICW ‐ RW and SISW ‐ RW exhibit increases in ultimate load by 67.9% and 20.9%, respectively, demonstrating improved bending strength. The influence of different weft structures on fracture morphology and mechanical properties shows that the straight interlaced structure, with a 10% reduction in weft yarns, exhibits superior tensile and bending properties compared to the curved interlaced structure, although its fracture morphology is more irregular. The curved interlaced structure has a higher weft yarn content, which enhances the lateral confinement, resulting in a smoother fracture surface. Although the FOW structure exhibits the highest tensile strength, its bending strength is the lowest due to the lack of weft yarn support, making the fibers in localized areas prone to stress concentration and resulting in single‐point failure.