Detecting delamination zones in composites by embedded electrical grid and thermographic methods

The proposed approach assumes that the composite structure is equipped with a specially designed electrical circuit with a 3D grid layout, composed of high resistivity elements embedded in the structure. The special layout of the electrical circuit activated by small currents provides scattered sources of thermal field in the laminate. It is assumed that the circuit elements exhibit failure which is coincident with the commencement of delamination. These breaks in the electrical circuit cause variations in the thermal field which can be observed by a long-wave thermovision camera. The paper is focused on two research aspects. First, some numerical simulations are presented to examine the potential of the idea itself. Next, a simple experiment using a composite sample with a hand-fabricated electrical grid is described. The performance of the grid for an arbitrarily selected position of defect in the investigated composite shows high potential for damage detection