Quantitative test of delamination defects in CFRP with surface interference by laser thermography

Remote onsite inspection and quantitative evaluation of internal delamination defects in carbon fiber reinforced polymer (CFRP) structures is of great significance in practical engineering applications. In this paper, a new method for quantitative test and 3D imaging of internal delamination defects in CFRP with surface interference by long pulse laser thermography is developed. The variation of surface temperature field in a CFRP plate with both defect and surface interference irradiated by a uniform laser source was analyzed by simulation and experiment. Image processing of the collected laser thermography image sequence was carried out to obtain the size and shape of the possible defects. Meanwhile, a method with using the peak time of the temperature difference curve was developed to precisely evaluate the defect depth and eliminate the surface interference. The information was then combined to achieve 3D visualization imaging of the actual defects.