Energy balance and assessment of the pressure build-up around a bolt fastener due to sparking during a lightning impact

Abstract

This work is devoted to the calculation of the energy balance associated with the formation of an electric arc between the bolt shank and an inner structural part of the fuselage during a lightning strike. Assessment of the pressure build-up in the confined volume around the bolt fastener has also been performed. This pressure rise comes from the temperature increase and from the mass density increase (melting and vaporisation of materials). Previous electrical measurements performed by Airbus Group during a lightning test campaign have been used to calculate the total available electrical energy. The energies necessary for melting and vaporisation of bolt and rib are derived from thermodynamic properties of aluminium and titanium. A numerical code has been developed to determine the chemical composition (under the local thermodynamic equilibrium [LTE] assumption) and the internal energy of the plasma for air-Al/Ti mixtures. Plasma and material radiation losses and heat conduction losses have also been evaluated. Finally, an analytical model has been implemented to determine the overpressure as a function of the deposited electrical energy, the energy involved in the arc formation, the energy necessary for melting and the plasma composition and mass density. With this approach, maximum pressure values are in the range 200–330 bars.

Damage Investigation of Carbon-Fiber-Reinforced Plastic Laminates with Fasteners Subjected to Lightning Current Components C and D

“…During a lightning strike, the resin on the inner wall of the fastener hole is pyrolyzed and gasified, which generates high-temperature, high-pressure gas [37]. The heated gas expands rapidly, producing a high-speed gas flow doped with black particles, which may be the product of carbon fiber sublimation and pyrolysis carbonization at high temperatures [38].…”

Arc fault power balance in AC and DC electrical aeronautic networks: influence of pressure and cable material

“…The power lost by conduction in the cables and lost by electrodes' radiation is assumed to be negligible. It is clearly established from previous work that the power radiated from materials is negligible in the balance of energy exchanges at the electrodes [29][30][31].…”

A comprehensive study of the radiative properties of NO—a first step toward a complete air opacity

“…Radiative properties of heated air species are vital ingredients in detecting, modeling and characterizing many physical objects and phenomena for atmospheric science [1][2][3][4][5], exoplanets [1,[6][7][8], lightning [1,6,[9][10][11], meteoroids or vehicle (re)entry [12][13][14][15][16][17][18][19][20], electrostatic discharges or plasma Air species moles as a function of temperature along the Hugoniot of ambient air, calculated with the thermochemical code Magpie [38]. Here, a typical humidity of 35% was utilized.…”