Research on foldable two-matrix 3D braided composites: Manufacturing and bending progressive damage

Three-dimensional braided composites have the potential to enhance the performance of composite hinges due to their high interlaminar strength, structural integrity, and damage tolerance. In this study, we first developed a multimatrix subdomain composite technique for fabric composites with 3D structural fabrics to fabricate multimatrix 3D braided composites. On the basis of this fabrication method, we designed a foldable 3D braided composite material using the rigid–flexible domain design method commonly used in flexible metamaterials. Experimental studies demonstrated that the material had ultrahigh rigid–flexible region connection strength and high rigid-region load-bearing capacity. It also had a reproducible, hermetically sealed large deformation capacity and required only a small amount of external force action and energy consumption. In addition, we revealed the progressive damage mechanism of foldable 3D braided composites during large deformations in bending, which guided the design of the flexible metamaterials.