Experimental and numerical analysis of damage mechanisms for carbon fiber-reinforced polymer composites subjected to lightning strikes

[Display omitted] •Lightning strike process of CFRPs is inspected via optical and thermal observations.•Internal damage is deduced by analyzing surface and microstructural changes.•Regions of lightning-induced damage are divided and quantitatively analyzed.•The dynamic conductivity properties of CFRPs were introduced in a numerical model.•Criteria for assessing in-plane damage and in-depth damage are proposed and verified. This study aims to reveal the damage properties and mechanism of carbon fiber-reinforced polymer (CFRP) composites subjected to lightning current component A by artificial lightning tests and simulation analysis. The lightning strike process was observed by using a high-speed camera and infrared temperature measurements. The surface damage and internal damage were inspected via ultrasonic and 3D X-ray scanning. The damage behavior of CFRP composite was deduced and the damage regions were quantitively analyzed by detecting the surface morphology and microstructural changes and analyzing the lightning strike process. The results indicated that the lightning-induced damage included lightning attachment damage due to direct contact with the lightning arc, laminate peeled-off damage caused by the explosive gas impact, and internal delamination induced by expanding pyrolysis gas. A coupled thermal-electric CFRP model, which first introduces the dynamic conductivity of CFRP materials, was established. The comparison results indicated that the Joule heating-based numerical model can simulate the evolution of thermal damage well, although the laminate peeled-off damage resulting from the mechanical impact was not included in the simulation scope. A temperature field criterion and a pyrolysis degree field criterion were proposed and verified for evaluating in-plane and in-depth damage with acceptable deviations.