Experimental and theoretical evaluation of aluminium deflection due to lightning strikes

This paper focuses on the displacement of aluminum plates subjected to the forces generated by a lightning current in order to compare modelling and experimental results directly. The electromechanical forces produced during lightning strikes can cause catastrophic damage and hence there is a need to understand the performance of existing and new materials under such extreme conditions in order to improve the ability to withstand these forces and minimize damage. Half-meter square 2mm thick aluminum plates were struck with a range of lightning currents from 40kA to 100kA. A computer model using a constant direct current input was used to predict the point of maximum deflection immediately following a strike which was compared to the measured maximum deflection from the corresponding experiment. Both model and experiment demonstrated an approximately linear relationship between maximum deflection and lightning current for aluminum. In addition, the experiment exhibited damped oscillation behavior following the maximum deflection and the extent of this was also related to magnitude of the lightning current. It was also found that, in the experiment, the test sample experienced an additional force, presumed to be due to air pressure, which could be corrected for. Overall, the static model and dynamic experiments showed close agreement with differences likely due to factors in each respective study.