Effect of Z-binder architecture on interlaminar shear properties and damage mechanism of 3D woven composites

• A comparison of four Z-binder architectures under identical conditions reveals their distinct roles in interlaminar shear performance. • All architectures exhibit a distinctive double-peak shear response, explained by a new mechanism of Z-binder-activated load redistribution after initial failure. • Ex-situ Micro-CT directly captures how distinct Z-binder geometries control damage evolution, from guided crack propagation to effective delamination suppression. • The established performance ranking links Z-binder geometry to damage tolerance, providing clear design guidelines for shear-critical applications. 3D woven composites rely on Z-binders to provide through-thickness reinforcement, yet how different Z-binder architectures govern interlaminar shear behavior and damage evolution remains insufficiently understood. This study establishes a unified experimental framework to systematically compare four representative architectures—layer-to-layer angle-interlock (LA), layer-to-layer orthogonal-interlock (LO), through-thickness angle-interlock (TA), and through-thickness orthogonal-interlock (TO)—manufactured under identical material systems and processing parameters. Short-beam shear tests reveal a characteristic F 1 – F 2 double-peak response in all architectures, and a architecture-dependent mechanism is proposed to explain secondary load recovery through binder-activated load redistribution. Ex-situ Micro-CT is employed to capture progressive damage at four critical loading stages, enabling the first direct comparison of architecture-controlled damage pathways. The results show that the four architectures exhibit distinct damage evolution behaviors. LO shows early interfacial sliding and rapid delamination due to weak adjacent-ply reinforcement. LA promotes directional crack growth along shallow inclined binders, forming oblique shear bands. TA leverages oblique full-thickness Z-binders to segment shear bands, deflect cracks, and delay catastrophic failure despite initial micro-damage. TO demonstrates the most uniform binder restraint, effectively localizing damage and preventing dominant delamination planes.