Thermographic data analytics-based damage characterization in a large-scale composite structure under cyclic loading

Large-scale composite structures such as aircraft wings and wind turbine blades undergo cyclic loading in operation. In-service damage often generates excessive heat due to material frictions and it could be detected by thermography. This study develops a methodology to quantitatively analyze such structural damage based on thermographic data analytics. A full-scale composite wind turbine blade is inspected using passive thermography when it is subject to cyclic loads in laboratory. The damage region is identified from thermographic images and it is tracked automatically using image processing. The damage region is subsequently characterized on both overall and detailed levels. The change of the damage status versus fatigue cycle number is analyzed and the information regarding the growth of the damage area and the damage severity is provided. The initiation and the progress of damage are investigated based on the temperature and the enthalpy change in the damage region. This study provides a viable solution for efficient structural health monitoring and damage prognosis of large-scale composite structures under cyclic loading.