Scaling up bone-inspired reinforcements: tunable structural performance for next-generation bioinspired composite laminates

Architectural design provides an effective pathway to tune the mechanical response of fiber-reinforced composites without altering material composition. Inspired by the concentric architecture of osteons in cortical bone, this study presents a framework for the design, modeling, and fabrication of multilayered cylindrical osteon-like structures (OLS) as reinforcements with tunable properties. A custom pull-winding technique capable of producing continuous multilayer OLS with millimeter-scale diameters was developed. The OLS were evaluated under uniaxial loading through experimental testing and finite element (FE) simulations, including representative volume element-based models, with linear and nonlinear buckling analyses performed to assess structural stability. In addition, the FE model, validated against experimental results, was used as a tool to systematically investigate the effect of stacking sequence and fiber orientation on the mechanical response of the OLS. The combined experimental and numerical analyses allowed the definition of a design space for OLS length selection considering both material strength and buckling-driven instability. The results highlight the key role of fiber orientation, with OLS configurations having fibers running parallel to the OLS axis exhibiting increased axial stiffness and improved buckling performance. This framework lays the groundwork for the future development of bio-inspired laminate systems incorporating multilayer cylindrical OLS reinforcements.