In Situ Monitoring of Failure Modes in Composite Bolted Joint Structures Using CB/CNT Piezoresistive Sensor

Carbon fiber reinforced plastics (CFRP) have been extensively utilized in large composite structures and various advanced engineering applications. Consequently, the bolted joint structure is also applied to connect large composite structures, which must be monitored in real time to ensure structural safety and integrity. In an effort to enhance integration and monitoring sensitivity, this study investigates a novel method utilizing a carbon-based nanocomposite piezoresistive sensor network. The proposed sensor network comprises carbon black (CB) and carbon nanotubes (CNTs) as conductive fillers embedded within a polyvinylpyrrolidone (PVP) substrate. The conductive and mechanical properties of the CB/CNT piezoresistive sensor are extensively investigated in the study. Moreover, the inclusion of sodium dodecyl benzene sulfonate (SDBS) as a surfactant in the sensor aims to enhance the dispersion of the conductive fillers. Moreover, a sensor layout strategy for monitoring multiple failure modes of CFRP bolted joint structure has been demonstrated. The results show that different failure modes can be characterized by the resistance signal change of the sensor. The developed sensor network is specifically engineered to monitor multiple failure modes characteristic of CFRP bolted joints. The outcomes demonstrate the exceptional reliability of the proposed sensor in monitoring various failure modes and underscore its considerable potential in structural health monitoring (SHM) applications.