| Abstract [eng] |
This study investigates the application of electrically conductive sandwich-structured composites with an aramid honeycomb core for damage monitoring in unmanned aerial vehicles (UAVs). Honeycomb cores are susceptible to failure modes such as buckling, wrinkling, and delamination, which are difficult to detect using conventional damage detection methods. Various techniques have been applied in the aerospace industry, including fibre optics, accelerometers, and piezoelectric sensors. Although effective in some applications, these systems are often expensive, complex, and have limited ability to detect internal damage within the honeycomb core. To address these limitations, this study explores the use of electrically conductive nanoparticles for structural health monitoring (SHM). When embedded into a composite, conductive networks exhibit a piezoresistive effect – mechanical damage leads to an increase in electrical resistance, which can be measured. Specimens consisted of an aramid honeycomb coated with MXene nanoparticles and six layers of glass fibre, one of which was covered with carbon nanotubes. Additionally, carbon fibre threads and unidirectional carbon fibre were integrated into the composite to measure local electrical resistance using a multimeter. Following electrical measurements of the individual components (honeycomb and glass fibre), an analytical model based on Ohm’s law was developed. The model demonstrated that the sensitivity of the electrical resistance of the composite depends on the relative conductivity of the individual layers. Composites were tested for compression, three-point bending, delamination, and temperature. During compression testing, when a local indentation 4 mm deep was introduced, the highest resistance change was recorded closer to the measurement channel due to defects in the conductive nanoparticle network. The delamination tests showed that, as the upper glass fibre layer was gradually separated from the honeycomb, the composite resistance increased exponentially. Three-point bending tests revealed a correlation between resistance change and deflection size. As the temperature varied from –14 °C to +70 °C, the relative resistance of the composite decreased by 50%. Furthermore, the study presents a 13 × 27 cm composite wing prototype equipped with six measurement channels connected to an “Arduino Nano ESP32“ microcontroller. The system measures electrical resistance in the channels in real-time and transmits the data wirelessly via Wi-Fi to the “Arduino IoT Cloud Remote” mobile application, where damage initiation and propagation can be graphically monitored. This technology enables the identification of honeycomb damage, fibre delamination, local cracks, and indentations. |
