Out-of-plane shear properties and failure mechanism of 3D braided laminated composites

Three-dimensional (3D) braided composites are extensively utilized in aerospace laminated composites owing to their superior out-of-plane shear properties and interlaminar delamination resistance compared with two-dimensional (2D) textile laminated composites. However, existing laminate models remain incapable of elucidating the enhancement mechanisms underlying the superior out-of-plane shear properties of 3D braided architectures. Understanding the influence of 3D braided yarn architecture on out-of-plane failure mechanisms is critical for enabling rapid design and batch-efficient manufacturing of aerospace composite components. This study has established a refined mechanical model for 3D braided laminated composites by integrating Hashin3D failure criterion with cohesive traction-separation law. The model quantitatively decoupled the respective contributions of braided architecture and interlaminar interfaces to out-of-plane failure. Results reveal that 3D braided laminated composites exhibit mixed failure modes of buckling and delamination, whereas 2D textile laminated composites failed predominantly through interfacial delamination. This divergence stems from the reduced interlaminar interfaces in 3D braided laminated composites mitigated catastrophic delamination risks. Concurrently, the interlaminar interlacing yarn architecture suppresses interfacial cracks propagation thereby enhancing out-of-plane properties.