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.

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.

The effect of conductive carbon black (0.5 wt%) on the properties of carbon fiber-reinforced epoxy resin (Rockwell hardness, Charpy impact strength, tensile and flexural properties, electrical conductivity, and resistance to lightning discharges) was investigated. The composites were obtained by the infusion method. A slight decrease in flexural modulus was observed, while the hardness and Young's modulus increased. The resistivity decreased four times. Simulated multiple lightning discharges confirmed the better electrical conductivity of the composite with the addition of conductive carbon black, which resulted in five times decrease in the laminate damage area.

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Open air experiments were conducted of surge current distribution in the lightning protection system, supplying cable and electrical installation of a test house equipped in household appliances. Surge currents were injected from the generator into the installation. Current distributions in elements of tested system were measured with multi-channel electro-optical system. To verify the experimental results the simulations of surge current in the test house modeled in ATP-EMTP were conducted. The results indicated a significant influence of frequency dependent parameters of the test house elements on both the amplitude and the shape of current waveforms.

A study of the relative permittivity and electric strength of dielectrics printed by focus deposition modeling was presented. These electrical parameters determined the life-time reliability of devices made of dielectrics. Samples of PLA, ABS, PETG and ASA were tested according to IEC specifications. The dependence of the electrical properties of the samples on the type of material and printing precision was observed. Relative permittivity tests were carried out in the acoustic frequency band from 20 Hz to 20 kHz. It allowed analysis in a higher band than has been done in other publications to date. The electric strength of materials at 1.2/50 μs surge voltage was examined, which has not been widely analyzed before. Weibull plots, as a basis for determining the risk of failure, were prepared. The PETG FR (flame retardant) had the highest electric strength value, while PLA had the lowest. The differences with respect to tests at AC voltage were demonstrated. The printing technique affects the electrical strength value and location of potential electrical break-down.