Impedance Measurement of multidirectional carbon fiber reinforced polymer laminates with real-time simulated lightning impulse currents

Abstract:
Measurement on the impedance of multidirectional carbon fiber reinforced polymer (CFRP) is obstructed by the real-time action of lightning impulse currents on test samples. Most studies compromised to using direct currents/DC to probe CFRP impedance, leaving evident misrepresentation and even deficiency in consideration of the permeation flow, tunneling effects, and field-induced emission to high voltage. This work conducts impedance measurement of CFRP under the real-time simulated lightning impulse currents. A new test sample contact-fixture device is designed. Through proposing an equivalent multidirectional circuit model, impedance in CFRP fiber direction, in-plane perpendicular fiber direction, and thickness direction can be deduced. Results are verified with the thermoelectric coupling model in CFRP lightning damage, together with experimental findings. Parameters acquired by the DC method are also compared and it indicates that accuracy of in-plane damage prediction is improved by 16.3% with this proposed approach, and increased by 24.8% for the depth direction. This study can help refine predictive models of CFRP damage to lightning strikes.