This paper presents the obtained results of experimental tests and modelling of lightning disturbances that were propagated in a model of aircraft cable bundle and caused by multiple lightning return-strokes interactions. The work is a continuation of previous research, which was concerned mainly with the interaction of lightning discharge with a single return-stroke. The section of the cable harness arranged above the metal plate was investigated. In one of its wires, a multiple-stroke current representing indirect lightning effects was injected from an impulse current generator dedicated to avionics immunity tests. Overvoltages induced at the ends of other wires surrounded by a braided shield, as well as the influence of line parameters and shield grounding condition on the shape and level of observed transients, were examined. The computer simulation results match the measurement data with satisfactory accuracy, and therefore, the presented model can be used to estimate indirect lightning effects in the wiring harness of avionics.

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Carbon fiber reinforced polymer (CFRP) composites are lightweight and an increasingly used material with good mechanical properties. In the aviation industry, they are also required to have specific electrical properties that guarantee resistance to the direct and indirect lightning effects. The paper is focused on the description of a test stand and development of a method used to determine the electrical characteristics of conductive CFRP laminate samples with the use of high current impulses of lightning nature. Samples of three laminates (square format with side 30 × 30 cm) with a different composition were tested on the constructed stand, confirming the possibility of characterizing this type of laminate sample in terms of electrical conductivity and resistance to the effects of lightning current. It was possible to observe the impulse current flow (with a peak value up to 15 kA and a rise time above 6 µs) from the high voltage electrode placed in the center of the sample in all directions towards the edge. The optical fiber measuring system was used to record the voltage and current time waveforms. The energy stored in the impulse current generator was sufficient to simulate the mechanical damage, such as burnout and delamination, that accompanies the direct lightning strike to structural elements made of CFRP. The influence of the matrix composition used for laminate fabrication on the test results describing the electrical properties of the tested CFRP samples was noted. The experimental setup allows the testing of specimens with a maximum width and length of 50 × 50 cm and any thickness with a peak current of up to 50 kA.

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