Flax fibers – epoxy with embedded nanocomposite sensors to design lightweight smart bio-composites

Lightweight smart bio-composites with damage sensing ability have been designed. Conductive polymer nanocomposites-based quantum resistive sensors (sQRS) have been embedded in a unidirectional flax fibers – epoxy bio-composite samples using a spray layer by layer process to monitor their structural health and eventually anticipate their failure. The in situ piezo-resistive responses of sQRS under monotonic and incremental cyclic tensile tests were analyzed to learn more about the damage mechanisms and predict behavior changes in the laminated bio-composites. sQRS signals were found to be well correlated with the typical mechanical traces of flax fibers/epoxy composites, thus allowing reliable conclusions about structural changes taking place in the core of the bio-composite under strain. In particular, the analysis of sQRS gauge factor evolution with strain level proved to be helpful to assess the probability of damage. This new contribution to the understanding of flax fiber-based composites’ mechanical behavior is expected to be of special interest as the sliding of fibrils weakly assembled in bundles makes it difficult to approach.