Determination of Crack Surface Orientation in Carbon Fibre Reinforced Polymers by Measuring Electromagnetic Emission.

Electromagnetic emission (EME) generated by fracture of carbon fibre reinforced polymers (CFRP) is studied. The fracture is induced to cross-ply CFRP by mechanical loading in a three-point bending configuration. An EME acquisition set-up operating on the principle of capacitive coupling is used to measure the low frequency (kHz-MHz range) electric field whose generation is attributed to the charge redistribution accompanying the fracture processes. Multiple, differently oriented EME sensors, for the simultaneous EME measurement with different source-sensor orientations, were applied to account for the directionality of the EME sources and their generated electric fields. A method to deduce the crack orientation based on the emitted EME field's directionality is proposed. A comparison between the angles of the EME sources obtained by this method and the actual crack surface orientations as determined by computed tomography is made. [ABSTRACT FROM AUTHOR]