A structure-integrated nanocomposite sensor system capable of simultaneous measurement of omnidirectional strain and temperature

Strain-based structural health monitoring (SHM) systems are widely used for composite structures, given the unpredictable failure mechanisms associated with their heterogeneous nature. However, conventional strain sensors are constrained by their unidirectional sensitivity and their inability to differentiate strain from temperature effects without additional sensors, leading to complex configurations and extensive wiring. To overcome these limitations, a carbon nanotube (CNT)-based omnidirectional sensing system was developed as a structurally integrated nanocomposite surfacing layer for composite structures. This novel sensor system enables the detection of strain in all directions using a single nanocomposite sensor, while simultaneously measuring temperature to isolate its effects. Experimental results demonstrated that the sensor accurately measured the full in-plane strain tensor under tensile loading, closely aligning with reference data from a 3-element strain gauge rosette. It also exhibited high temperature accuracy, with a maximum error of 0.3%. By reducing the number of required sensors and wiring while maintaining precise measurements, this nanocomposite sensor system significantly simplifies SHM configurations. These findings underscore the potential of the CNT-based sensing system as a streamlined, efficient solution for aerospace and other advanced applications requiring reliable, multi-functional SHM systems.