Structural Health Monitoring of Repairs in Carbon-Fiber-Reinforced Polymer Composites by MWCNT-Based Multiscale Sensors

Abstract

The precision maintenance of delaminated carbon-fiber-reinforced polymer composites calls for the high demand of continuous, in situ monitoring of the damage-repair process along with the in-service status of the repaired region. Moreover, the repaired region faces a high risk of re-damage; therefore, in-service monitoring is highly desired. However, the current repair process lacks the in situ monitoring function, leading to the mechanism and evaluation of the repair approach being unclear. Here, we implanted multi-wall carbon nanotubes (MWCNTs) at the interface between the carbon fiber and resin matrix of the damaged region to achieve in situ monitoring of the repair, compression, and seawater-immersion processes. By depositing both the coupling agent and MWCNTs at the interfaces, a high recovery efficiency of 85% was achieved, which was independent of the delamination pattern shapes. The electric resistance changes of MWCNT-modified panels could effectively identify the resin permeation and solidification processes and could be used to in situ monitor the structural health of the repair region when it is subjected to the compression and seawater immersion tests. This strategy, combining high-efficient repair and precision maintenance, demonstrates potential in the structural applications of carbon-fiber-reinforced polymer composites.