Effect of the electric current on the impact fatigue strength of CFRP composites

The present study intends to analyse and quantify the effect of the electric exposure on the impact fatigue strength of carbon/epoxy laminates subject to a DC electric current flowing through-thickness at the impact point. For this purpose several laminates were tested with different stacking sequences: [0]16 and [0i,90i]S, i = 2, 3, 4, 5. The samples were submitted to a DC electric current of 1 A, corresponding to an electric current density of 0.142 (A/mm2). The unidirectional samples were exposed over 2 h, 4 h and 8 h, and the cross-ply ones to 8 h. The tests were carried out using a drop weight-testing machine and a 10 mm diameter impactor. It was possible to conclude that the exposure to the electric current decreases the impact fatigue life, but the unidirectional laminates show to be much more sensible than the cross-ply ones as consequence of the higher pre-damages induced. Thicker samples are also minus sensible to the effects promoted by the electric current and, consequently, the impact fatigue life is less affected.