Preparation and Characterization of a Novel Gradient Needled Composite Preform

Traditional gradient needled fabrics consist of fiber felts and base fabrics. The overall fiber volume fraction is low, resulting in weak mechanical properties. In particular, fiber felts restrict the fabric's compressive resistance. In addition, the density difference between felt and base fabric layers is significant, making it difficult to achieve a uniform transition in fiber volume fraction through the fabric. To address this issue, grid fabric with controllable areal density was used to replace the base fabric, and a grid fabric‐based gradient needled fabric was developed. By adjusting needle type, fiber‐felt areal density, and needled density, seven samples were prepared. The study investigated fabric structure, interlayer peeling, in‐plane tensile strength, and compressive properties, using traditional gradient needled fabric as a control. The results showed that the proposed fabric achieved a more uniform transition in fiber volume fraction, with interlayer peeling, in‐plane tensile strength, and compressive resistance improved by 8.3%, 29.3%, and 4.6%, respectively. Needle type, fiber‐felt areal density, and needled density significantly affected mechanical properties. The optimal parameters were medium needles, a fiber‐felt areal density of 75 g/m 2 , and a needled density of 15 needles/cm 2 . This fabric demonstrated excellent mechanical properties and great potential for high‐speed aircraft components.