Flexural behavior and failure mechanism of multi-structure 3D woven composites

Through integrating two distinct woven structures within one structure component, termed as “multi-structure 3DWC”, gradient or location-specific properties can be achieved to satisfy the performance requirement of the structure under complicated service loading conditions. To understand the mechanical deformation and failure behavior of the multi-structure 3DWC, a systematic experimental and numerical simulation study was conducted for two baseline single-structure 3DWCs (curved shallow-crossing linking weave (A) and 1–3 twill weave (B)) and their integrated multi-structure 3DWC under three-point bending loads. Parametric subcell models were developed based on a multi-scale modeling framework and validated against experimental results. Through detailed analyses, a complicated multi-stage response is reported, and the failure of the multi-structure 3DWC is found to be attributed to localized compressive kinking followed by tensile fracture, driven by stiffness mismatch and concentration of bending curvature across the transition region. Parametric studies for the multi-structure 3DWC with varying proportions of structure A/B in a specimen further reveal the strong dependency of effective mechanical response on the structural partitioning, as well as the position relationship between the transition region and the loading location. These findings elucidate the mechanical response and damage mechanisms of multi-structure 3DWC, also providing guidance for the optimized design of sectorization in 3DWC structures.