Damage characteristics of T800 carbon fiber plates subject to typical hail impact loads

With the deterioration of the natural climate, hail impact has become a threat that cannot be ignored by civil aircraft. To study the hail impact damage characteristics of high-performance carbon fiber composites used for civil aircraft, we first investigated the impact force characteristics of ice spheres under high-speed impact through experiments, and the impact force time history curves of ice spheres under different speeds were obtained using an air cannon test system. At the same time, to make the speed range of the ice sphere more extensive, some existing experiment data were introduced as a comparison to obtain the linear growth relationship between the peak impact force and the kinetic energy of the ice sphere. Subsequently, a single ice sphere impact test was conducted on the T800/3200 carbon fiber composite laminates. It was found that the concave of the front core damage area forms a 45° angle with the boundary of the target plate, which is related to the carbon fiber layup mode, and the damage degree depends on the initial speed of the ice sphere. To further quantify the relationship between the damage degree of the laminate and the kinetic energy of the ice sphere, ultrasonic C-scanning was used to obtain the damaged area of the target plate, and the damage percentage was extracted by software analysis. The results show that the percentage of internal interlayer delamination increases linearly with the kinetic energy of the ice sphere. After that, repeated impact tests of ice spheres were carried out on the target plate with the same thickness, and as expected, the macro damage degree increased with the number of impacts. Finally, the front and back surfaces of the composite laminates were completely delaminated, resulting in a large number of fibers being pulled out and displaying a penetrating through-thickness damage pattern. The deflection of the center point of the target plate was selected as the quantitative damage index, and according to the data analysis of the measured results, it was found that there is a quadratic relationship between the deflection of the center point of the carbon fiber plate and the accumulated kinetic energy of the ice sphere. The apex of the parabola can well reflect the accumulated kinetic energy required for the target plate penetration.