Comparison of Nondestructive Testing Methods on Detection of Delaminations in Composites

TLDR

Delamination is a common defect in carbon‑fiber reinforced plastic components used in aircraft and wind‑turbine blades. The study compares ultrasonic, eddy‑current, flash thermography, and pulsed‑eddy‑current simulated thermography to evaluate a newly developed PEC thermography system at NUAA via a UK‑China collaboration. A PEC‑stimulated thermography system was built at NUAA, extending prior work, and used alongside other NDT methods to test man‑made delaminations of varying size and depth. PEC‑stimulated and flash thermography accurately indicate delamination shape, and PEC‑stimulated thermography uniquely evaluates fibre orientation.

Abstract

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 system at 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.