Electric current return pathways on aircrafts
Previously, aircraft fuselage elements and its primary structures were made from metals. This provided a natural current return network (CRN) to carry functional and fault currents or handle electrostatic charge draining and electromagnetic shielding. The recent transition to increased usage of composite materials provided cost and weight savings while enhancing performance. Unfortunately, composite materials have poor electrical conductivity and there is a need for dedicated conductive CRN pathways such as almost equipotential electrical network (ALEEN). The EU-funded 'Optimizing electrical network in airplane composite structure' (GENIAL) project focused on the electromagnetic characterisation of the ALEEN structure. Accurate electromagnetic characterisation will enable the proper design of electrical systems such as electrical wiring interconnection system (EWIS) without the need for repeated bread boarding. Project partners developed a computer-aided engineering (CAE) tool that is able to input aircraft and ALEEN geometries and material properties from the computer-aided design (CAD). This evaluates the equivalent impedance matrix at ALEEN terminals in the frequency range of 0 to hundreds of kilohertz. Aspects such as the EWIS and the electromagnetic interaction with aircraft body are also accounted for. GENIAL applied full-wave 3D modelling based on the surface formulation of the partial element equivalent circuit method, considering all electromagnetic interactions such as coupling and proximity effects. This type of method was selected for its effectiveness in the low-frequency region. Particular effort has been devoted to high-fidelity modelling to improve accuracy without the need for simplifying the numerical model with respect to the CAD model. The developed tool will be applied in the design verification and production stages of ALEEN structures. To test the performance of the CAE procedure, the numerical method is expected to be applied to a real aircraft.
Keywords
Numerical methodology, software tool, aircraft, composite, current return network, almost equipotential electrical network, electromagnetic compatibility
