Edge glow: A combined voltage/power controlled mechanism?

The improvement of CFRP mechanical properties has led to the development of new materials in aeronautic industry. In the frame of engineering experiments for developing lightning strike protections, a phenomenon has been observed on edges of aircraft composite substructures, consisting in a bright glow combined with strong ejections. Uncertainties in the nature and the severity of this threat, so-called “edge glow”, make necessary to consider it as a potential fuel ignition source and to implement appropriate lines of defense. Behind the most intense event that seems controlled by the voltage drop across plies, a second edge glow regime seems related to a thermal mechanism at pre-existing contacts on the composite edge. The context of this work is the mitigation of edge glow phenomena with appropriate protection designs and installation principles. This paper presents experimental investigations on generic test coupons that aimed at understanding how current distributes into a local assembly governed by non-linear contacts and how far it impacts edge glow occurrence and intensity.