Pipeline Structural Health Monitoring With Curved Multi‐Walled Carbon Nanotubes/Epoxy Composites: Mechanical and Piezoresistive Properties

ABSTRACT Trenchless rehabilitation provides a more efficient method for pipeline repair compared with traditional excavation techniques. However, effective monitoring of deformation and damage in pipelines after rehabilitation and during service remains limited. In this study, a multi‐walled carbon nanotube (MWCNT)‐reinforced epoxy (EP) matrix composite was developed for rehabilitation and health monitoring of curved pipeline. The mechanical and piezoresistive properties of curved composites were systematically investigated through three‐point bending tests by examining the effects of MWCNT content, curvature radius, and specimen thickness. Results showed that 0.7 wt% MWCNT content yielded optimal mechanical performance, while 1.0 wt% provided stable electrical conductivity for sensing. The curved composite exhibited superior bending strength and piezoresistive sensitivity compared with its flat counterpart, with maximum improvements of 13.4% and 31.3%, respectively. A smaller curvature radius enhanced both properties, and a straight‐bend analysis boundary was identified at 400 mm. Furthermore, increased thickness improved the piezoresistive response. The curved composite demonstrates significant potential for pipeline structural health monitoring owing to its morphological conformity and self‐sensing capability.