Self‐Sensing Behavior of Multi‐Walled Carbon Nanotubes Reinforced Epoxy Matrix Composites Under Static‐Dynamic Tension

ABSTRACT Underground drainage pipelines undergoing trenchless rehabilitation require effective structural health monitoring, yet existing sensing techniques are significantly limited in harsh buried environments. In this study, a multi‐walled carbon nanotubes reinforced epoxy matrix (MWCNTs/EP) composite was developed for structural health monitoring of drainage pipelines. The self‐sensing behavior of the composite was investigated through static and dynamic tensile tests coupled with resistance measurements. The results showed that the addition of MWCNTs reduced the composite resistivity, with a percolation threshold of 0.7 wt% at which the resistivity decreased by approximately two orders of magnitude. The resistance increased exponentially under small strain ( 6%) and linearly under larger strain, while the composite maintained consistent sensitivity over a wide strain range. The repeatability of the self‐sensing response depended on both strain amplitude and cycle number, and good reproducibility was achieved at 5%, with a repeatability index below 0.5. The in situ resistive damage followed an exponential function as strain increased, and sensitivity analysis determined the repeatable monitoring range to be 8%. This work offers a self‐sensing material for real‐time deformation monitoring of rehabilitated drainage pipelines.