Experimental And Simulation Study Of The Lightning Strike Damage Of Carbon Fiber Composites

Carbon fiber composite material has been more widely used in the aerospace vehicles as the main structural material for its excellent performance in light weight, high strength, high modulus and corrosion resistance. But this new material is more sensitive to lightning than conventional metallic materials. Large-scale usage of the carbon fiber composite material will undoubtedly make flying more dangerous, so there are many safety concerns about carbon fiber composite aircraft in the lightning environment. The study of lightning damage of carbon fiber composite material ensuring its application in aerospace safety is very important for our country to grasp the core design and manufacture technologies of the big aircrafts as soon as possible.This paper presents an experimental study on the preparation technique of carbon fiber reinforced thermosetting resin matrix composite laminate. Interlayer toughening/electrical and thermal conductivity strengthening of the carbon nanotubes modified carbon fiber composite laminates specimens, specimens with the 3D anti-lightning functional surface layer, tension/compression specimens of carbon fiber composite laminates without hole and specimens with metal fasteners were prepared. According to different characteristics of the laminated lightning protection, corresponding artificial lightning tests were carried out and the lightning damage of laminates was analyzed. Specific conclusions are as follows:(1) the propagation direction of the lightning damage is along the longitudinal direction of carbon fiber, and then the fan-shaped damage areas are distributed symmetrically around the centre of the lightning strike; (2) residual carbon produced by thermal degradation of the resin deposited on the exposed carbon fiber, erosion, expansion, rupture and local thickening of carbon fiber can be observed in the micro-morphology of carbon fiber composite lightning damage; (3) with the increase of modified layers, the lightning protection performance of interlayer toughening/electrical and thermal conductivity strengthening of the carbon nanotubes modified carbon fiber composite laminates become good; (4) making comparison of different lightning protection modified carbon fiber composite laminates, the results show that specimens with the three-dimensional anti lightning surface functional layer perform best; (5) adding an equal amount of modified particles, the effect of nickel coated multi walled carbon nanotubes (Ni-MWCNTs) is better than adding carbon nanotubes (MWCNTs); (6) the usage of the metal fasteners on carbon fiber composite material increases the risk of lightning.In order to achieve the target of carbon fiber composite structure-electrical conductive integrated lightning protection design, electricity, heat, chemical degradation and other factors were involved. By using the finite element software ABAQUS user subroutine USDFLD, HEAVEL, the thermal degradation degree was introduced. Finally, the model of the thermal-electrical-pyrolysis analysis during the lightning damage process of carbon fiber composite was established, so as to realize the simulation of lightning damage process of carbon fiber composite laminates. The comparison of the finite element simulation results and experimental results verified the rationality of the finite element simulation method. On the basis of the analysis, the relationship between the influence factors of the lightning damage was studied. Specific conclusions are as follows:(1) involving temperature, time and space factors, the introduction of thermal degradation degree and the distribution of physical quantity help to explore the thermal damage behavior of composite plates, and the establish of the model of the thermal degradation related anisotropic thermal-electrical properties makes the results more reasonable; (2) the damage area, the damage depth and the damage volume are the three measure indicators of lightning damage, the damage volume is the best measure indicator of the lightning damage; (3) the amount of the electrical charge of the lightning current has the greatest impact on the damage volume, and the damage volume has logarithmic relationship with the quantity of the electrical charge and the action integral respectively; (4) the lightning damage volume has a strong logarithmic relationship with the electrical conductivity of the composite materials, and the thermal conductivity of the composites has no effect on the lightning damage.