Experimental investigation of the repeatability of direct damage induced by lightning strikes on metallic panels

Metallic parts of aircrafts that are used for fuel tanks areas or even for the fuselage can suffer from severe direct damage due to lightning strikes. Laboratory tests imitating lightning strikes follow standard regulations requirements that prescribe the current waveforms the structure must resist depending on the zone of the airplane. D+B+C* current waveforms are under concern here and are reproduced in by specific current delivery devices at DGA-Ta lightning lab. The present paper points out that in some cases, tests considered as identical from the standard regulation point of view can generate different damages in the plate, and even variability in perforation apparition. This paper proposes a damage severity index (DSI) that allows considering in an intrinsic manner the effect of the testing parameters related to the current waveform or from the sample modification. The analysis of the tests exhibits a threshold over which a critical crater occurs and the risk of perforation is maximal. We use the DSI to perform a sensitivity analysis on a small data set of lightning tests and quantify the positive or negative effects of significant current waveform or sample input parameters.