Programmable helix-tubular composites with bio-inspired architecture

The programmable materials have attracted attention for its groundbreaking functionalities across diverse applications, especially the curl-fiber reinforced composites inspired from collagen fibers. In this work, a novel helix-tubular composite (HTC) is developed through an integrated braiding-knitting fabrication approach. Experimental analyses demonstrate that the mechanical properties of HTC can be directionally optimized through parameterization of secondary conformational architecture and coupling states. Remarkably, HTC manifests triphasic nonlinear mechanical behavior analogous to native ligamentous tissues. This biomimetic response originates from synergistic interactions between the stiff helix conformation (the stiff conformation) and highly stretchable tubular conformation (the stretchable conformation). Furthermore, cyclic tensile evaluations reveal exceptional fatigue resistance exceeding thousands of cycles. This durability substantiates the composite's potential for replicating the multifunctional mechanical behavior of biological tendons and ligaments. These findings establish a methodological framework for engineering advanced materials with spatially programmable mechanical properties through conformational coupling.