Comparison of Nondestructive Testing Methods on Detection of Delaminations in Composites

Delamination is one of the most common defects in carbon fibre reinforced plastic (CFRP) components, such as those used in aircraft and wind turbine blades. To detect delaminations, different NDT methods such as ultrasonic (UT), eddy current (EC) scanning, flash thermography, and recent developed pulsed-eddy-current-(PEC-) simulated thermography are conducted for comparison and evaluation of the new developed PEC thermography systemat Nanjing University of Aeronautics and Astronautics (NUAA), China through UK-China collaboration. A PEC-stimulated thermography system is built at NUAA, extended from previous joint work between Newcastle and Bath Universities. Using these NDT systems, man-made, dedicated delaminations with varied diameters and depths are investigated and studied. Through this comparison, PEC-stumilated and flash thermography show relatively good indications of the shape of delaminations. The joint studies also show that PEC-stimulated thermography has unique advantage for fibre orientation evaluation.