Embedding stretchable, mesh-structured piezoresistive sensor for in-situ damage detection of glass fiber-reinforced composite

Structural health monitoring of composites is of critical importance for various practical applications. However, it is challenging to accurately monitor the damages of the host composites without compromising their me-chanical properties. Herein, a novel bioinspired, mesh-structured film that combines flexibility and stretchability is proposed as an embedded piezoresistive sensor for in-situ damage monitoring. The mesh film composed of carbon nanotubes and polyvinyl alcohol was prepared via a simple doctor-blading method. The embedded mesh film exhibited high compatibility with the composite and has negligible impact on its mechanical properties, which is significantly superior to the implanted solid film leading to severe decreases in both the tensile strength (-15.6%) and flexural strength (-35.5%). This effect is attributed to the fact that the epoxy could infiltrate the pores of the mesh film and form an interconnected interlayer, which is beneficial for preserving the mechanical properties. Meanwhile, the proposed mesh film was endowed with the capacity of in-situ damage detection, which was proved by the excellent coherence between the resistance change of the film and the acoustics detected by a commercial sensor. The excellent ability for damage detection demonstrates the great perspectives of the proposed mesh film for the structural health monitoring of composites.