Biomimetic construction of 3D needle‐punched CF/PEEK composites based on ladybug forewing structure for directional reinforcement

Abstract 3D needle‐punched CF/PEEK composites are a kind of composites with promising applications in multiple fields, such as implant materials, but their mechanical properties in the Z‐axis and interlaminar are still weak at present. In this study, a bio‐inspired reinforcement structure based on ladybug forewing was developed to achieve directed reinforcement of 3D needle‐punched CF/PEEK composites. Carbon fiber yarns were stitched into the 3D needle‐punched CF/PEEK preforms according to the set structure, and the bio‐inspired CF/PEEK composites were obtained after hot pressing. The interlaminar and in‐plane mechanical properties of the composites were investigated at different stitch lengths. The results showed that the addition of the bio‐inspired structure greatly improved the interlaminar shear strength of the composites, reaching 111.30 MPa, an enhancement of 95.06%. The in‐plane mechanical properties, including tensile, flexural, and compression, were also significantly improved to different degrees. The “structure‐effect” relationship in the bio‐inspired CF/PEEK composites was investigated, and the effectiveness of such a bio‐inspired reinforcement structure was demonstrated. This new reinforcement strategy provides a new idea for the improvement of the mechanical properties of multi‐stage carbon fiber‐reinforced thermoplastic resin matrix composites. Highlights The in‐plane and interlaminar mechanical properties of composites were simultaneously improved. Up to 95.06% improvement in interlaminar shear strength. A novel bionic strategy of directional reinforcement was developed. The “structure‐effect” relationship in the composites was investigated.