Dynamic experimental study on water droplet erosion damage behavior of composite coating structures for supersonic aircraft

The composite skin coating structure of the front edge of the supersonic aircraft body is deformed, cracked and even stripped due to the continuous impact of raindrops. The coating material used in this paper is based on carbon fiber T300 braided material, and its surface is coated with three different types of coatings. In order to reveal the rain erosion damage mechanism of the coating structure and establish the rain erosion damage criterion, the rain erosion test of three kinds of coatings was carried out by using the multi-jet rain erosion test device and the Hydro-impact test rig “Erosion-M”. In the experiment, the coating material is simulated under two different rain erosion conditions: continuous droplet impact in the same location and large range droplet impact in real rain field. The damage behavior of the surface and cross section of the coating damage under the two rain erosion conditions was characterized and analyzed by digital microscope and scanning electron microscope (SEM), and the influence mechanism of impact conditions on the rain erosion damage of the coating material was discussed. The results show that the typical damage pattern of the samples after multi-jet impact is a funnel-shaped damage pattern with severe damage in the middle and small damage all around. In the properties of coating materials, surface roughness has a significant effect on the latency of rain erosion damage, and mechanical parameters such as hardness and modulus mainly affect the expansion period of rain erosion damage. Among them, coating material 2 has better resistance to rain erosion. The damage degree increases with the increase of impact velocity and decreases with the decrease of impact Angle. The influence mechanism of roughness, modulus and hardness on rain erosion damage at different damage stages and under different impact conditions was revealed.