Cyclic Hailstone Impacts: Evaluating Aircraft Canopy Resilience

Hailstones exhibit variations in diameter and impact objects at different velocities influenced by airflow. The extent of damage inflicted by hailstorms is contingent upon both the size and speed of the hailstones. Accurately simulating hailstones is essential for conducting impact tests. In this research, artificial hailstones were created using a polyvinyl acetate (PVA) additive. Previous investigations indicate that a mixture comprising 12% PVA and 88% demineralized water is most effective in replicating the behavior of natural hailstones. The primary objective of this study is to establish an experimental setup for assessing the impact of hailstones on aircraft canopies. To support this goal, specific requirements for impact testing were outlined. Dynamic impact tests were conducted using two different aircraft dimensions. Artificial hailstones of 20 mm and 50 mm in diameter were successfully manufactured for the experiments. The designated velocities for these artificial hailstones were 20 m/s, 30 m/s, 60 m/s, and 120 m/s, for which the necessary air pressures were calculated. Experimental results confirmed that artificial hailstones of varying diameters could be effectively produced and that they impacted predetermined areas on the aircraft canopies. However, the study also found that artificial hailstones traveling at velocities exceeding 120 m/s failed to produce visible deformation on the aircraft canopies.