Quantification of the Material’s Resistance to Damage by Lightning

Abstract

The current work undertakes an attempt to establish a methodology towards determination of a universal constant of the material resistance to lightning. A proper quantification of the induced damage will enable a simultaneous comparison among various structural materials based on their dynamic responses in the simulated lightning environment. As an initial approach, evolution of damage was investigated in the lightning quasi electrostatic fields with the ensuing formation of the thermal plasma discharge characterized by the 200–500 A current in the 0.14–3.86 s time range in the unpainted aluminum cathodes at atmospheric pressure in air. Development of damage followed the kinetics law, where the process rate constant, , expressed as a dimensionless quantity of the relative change in damage volume or in material residual ultimate tensile strength, showed independence on current amplitude or material’s thickness with . Comparison of the damage volume and material’s loss through ablation suggested formation of damage as a result of metal melting. Linear dependence of the cathode temperature on arc amplitude at the attachment location revealed proximity to the alloy melting point for the 200 A arcs and temperatures exceeding melting approximately by a 1000 °K for the 500 A currents.