Squeeze-winding: A new manufacturing route for biomimetic fiber-reinforced structures

Natural materials represent ideal biomimetic models for materials design. However, the sophisticated natural hierarchical architectures are rather difficult to be implemented in synthetic FRCs and components through classic manufacturing methods. We propose a new method, called squeeze-winding (SW), specifically designed for the fabrication of FRC-tubes with a bone-inspired internal structure. SW represents a modification to the classic filament winding (FW) and is aimed at implementing a bone-like structure characterized by axially-oriented cylindrical features and achieving a high reinforcement volume fraction (~60%). The outcome of compression testing shows: a high repeatability of the mechanical characteristics achieved by SW, a higher fiber volume fraction of SW tubes compared to the conventional FW tubes, and improved mechanical properties. Moreover, we demonstrate how SW can be used to manufacture a sophisticated bio-inspired design, which mimics the cortical bone microstructure, ensuring enhanced mechanical properties compared to laminated tubes obtained by FW.