Damage Differences of Carbon Fiber Reinforced Polymer under Different Lightning Current Components

Carbon fiber reinforced polymer (CFRP) composite materials are often used in wind turbine blades, but they have lower electrical conductivity and are prone to damage due to lightning strikes. In this paper, simulative lightning current damage tests were carried out to CFRP laminates with a dimension of 500mm $\times 300$ mm $\times 3$ mm and a 24-layer layered structure. The current component A, with a peak current of 194kA, simulating the first stroke of natural lightning, and the component C, with a transferred charge of 240C, simulating a continuing current, were separately injected into the center of the CFRP laminate. Damage characteristics are analyzed using visual inspection and ultrasonic scanning. Obtained results show that, the energy of current component A with a large current amplitude but a short duration is released instantly through the fiber layup, resulting in a fiber burst zone with a direction in accordance with the layup. The current component C, with a large amount of transferred charge and a longer ablation time, can bring circular damage to CFRP laminate. The underlying physics for different damage created by two current components are further discussed.