Damage detection in natural fiber composites using vibrational analysis and a curvature-based indicator

Natural fiber-reinforced composite materials offer a sustainable and eco-friendly alternative to traditional composites in various sectors. For these materials, it is essential to develop new methods for characterizing and detecting internal defects and damages. This study aims to detect and locate damage in natural fiber-reinforced composite materials, specifically flax/epoxy beams and plates, which exhibit lower elastic moduli and higher damping compared to traditional composites. A new indicator based on vibrational modal curvature shapes and taking into account damping factor was employed to identify invisible low-energy impact damage and delamination. Experimental vibration tests on cantilever flax fiber composite beams validated the method’s effectiveness. The results show that the method can detect and localize hidden damage, with damage in flax/epoxy composites remaining generally more confined, whereas in carbon/epoxy composites it tends to spread over a larger area. • New indicator is validated for low-modulus, high-damping materials. • Damage propagation is more limited in flax fiber composites. • A custom drop-weight impact rig was built to investigate low-energy impacts on natural fiber • composite materials. • The indicator is capable to detect delamination damage.