Thermal Inspection of Subsurface Defects in Wind Turbine Blade Segments Under the Natural Solar Condition

This study explores the potential of unmanned aerial vehicles (UAV) thermography to inspect wind turbine blades using natural solar radiation. A comparative study of numerical analysis and experiments is presented. The simulation was performed using realistic solar boundary conditions. In parallel, outdoor thermal experiments were conducted utilizing a UAV on several customized specimens, including regular glass fiber reinforced polymer boards and a segment from a real wind turbine blade. The results demonstrated the detectability of solar thermography to inspect internal delaminations in blade structure. In particular, the results showed that the thermal patterns of the subsurface defects are dynamic throughout the daytime, which means the distinction between surface and interior defects could be attained. A comparison of two kinds of delaminations and surface defects is also provided.