Numerical and experimental investigation of silk/carbon hybrid composites: Mechanical properties and progressive damage

The limited toughness, fracture energy, and elongation of carbon fiber-reinforced composites restrict their broader application. In contrast, silk fiber exhibit high toughness and ductility, making them attractive candidate for hybrid reinforcement. In this work, silk/carbon hybrid fiber reinforced composite were fabricated using continuous natural fiber 3D printing followed by vacuum-assisted hot pressing. Mechanical tests combined with scanning electron microscopy was employed to evaluate the effect of silk fiber content on the mechanical properties and damage mechanisms of hybrid fiber reinforced composite. The incorporation of silk fiber enhanced the Mode I interlaminar fracture toughness by 62.32 %. With higher silk fiber fractions, tensile fracture energy and flexural ultimate strain improved by 153 % and 182 %, respectively. A finite element model based on the Hashin failure criterion was developed to accurately predicted the progressive damage, and the numerical simulation showed good agreement with experimental results. These findings demonstrate that hybridizing carbon with silk fibers provides a viable pathway to tailor toughness, ductility and other mechanical properties in composite systems.