Lightning Currents on Fastening Assemblies of an Aircraft Fuel Tank, Part I: Uncertainties Assessment With Statistical Approach

Abstract

This paper proposes a statistical approach able to assess the fastening resistances uncertainties in aircraft assemblies. This method relies on the use of the maximum likelihood estimation method, several statistical tests and/or statistical criteria. Using the Dassault-Aviation measurement database, distribution laws are established in order to characterize uncertainties in the lightning impact on the fasteners. A simple FDTD fastener model is proposed with a wire and a resistance. This generic model can represent any fasteners. The statistical model established from the fastener resistances state after a lightning shot is used to define the stochastic distribution values in the fastener electric model. This model is added to a 3D FDTD parallelepiped generic fuel tank model. In this article, we compare the current distributions between a composite and metallic fuel tank. The results highlight not only the model uncertainties effects on the statistical approach but also the fuel tank material choice impact. Index Terms-Statistical method, finite-difference timedomain (FDTD) modelling, fastener modeling, lightning effects, fuel tank aircraft, composite material.

Electric Power Systems in More and All Electric Aircraft: A Review

“…In addition, a damaged wire can adversely affect EMC and lead to EMI. Even though we avoid a detailed discussion, readers may refer to [138]- [140] for further study.…”

Lightning Currents on Fastening Assemblies of an Aircraft Fuel Tank—Part III: Validation of the Current Assessment Method With Measurement

“…The inherent inaccuracy of their results is due to strong uncertainties about the contact resistances values. Indeed, it has been demonstrated that their variability is strong and has an important impact for the lightning current estimation [3], [5], [6].…”

“…The proposed approach in [6], [7] is to merge an uncertainties model with a FDTD fastener model. A general method applied to the contact resistance uncertainties allows defining a probability law as uncertainties model [6]. This model represents the variability of the equivalent fastener resistance whatever the fastener type.…”

“…The uncertainties model is combined with the new fastener model. As in [6], [7], several simulations are realized in order to surround measurement. In addition, a sensitivity analysis on modeling is carried out in order to enhance the proposed surrounding.…”

“…Henceforth, equations, figures, or sections from Part X in[6],[7] are referred to using the prefix X ∈ {I, II}, e.g., Fig.I-1or Eq. (II-1).…”