Interfacial knotting and winding reinforcement for joining homogeneous and heterogeneous 3D continuous fiber lattices

Abstract

Reliable joining of independently fabricated continuous-fiber lattice units remains a critical challenge in architected composites because thin struts, porous topology, and non-planar interfaces limit effective load transfer and promote interface-dominated failure. Here, a permanent lattice-to-lattice joining strategy is developed by combining wet rebonding with mechanically reinforced fiber bridging using two architectures: localized knotting and distributed winding. Knotting introduces discrete anchoring across selected strut-level regions, whereas winding provides circumferential confinement over an extended joined interface. Mechanical evaluation under compression, monotonic tensile loading, cyclic tensile loading, and four-point bending shows that reinforced joints can retain or exceed the mass-normalized mechanical response of corresponding single-piece references, depending on reinforcement architecture and loading mode. Carbon fiber reinforced polymer (CFRP)–CFRP joints provide high stiffness and mass-normalized load-bearing performance, whereas CFRP–aramid fiber reinforced polymer (AFRP) joints introduce greater compliance and energy dissipation. Material-level impact tests on single-piece CFRP and AFRP lattices are reported separately as supplementary context. These results identify interfacial reinforcement architecture as a key design parameter for permanent assembly of continuous-fiber lattice structures.