The mechanics of water entry has been investigated extensively for rigid and deformable media, for a wide range of engineering applications. Limited attention has been paid to understanding the water entry process of structural systems with both rigid and deformable components. Inspired by diving animals such as the gannet, the paper experimentally investigates the dynamic characteristics of diving systems (divers) with different springs and head shapes. While the body shape plays an important role in dissipating the impact energy due during water entry, introducing springs into the neck assembly of a rigid diver reduces its maximum impact acceleration and the jerk by more than 50%, regardless of the tested head shapes. The experimental investigation examines the water entry performance of two diving systems: round and cone head. The effect of the stiffness of water-entry mechanics of each system is compared for rigid (no spring), firm spring, and soft spring, totaling six experimental cases. The impact velocity ranges from approximately 3.1 to 5.9 m/s. Introducing rigid-deformable interfaces into the design of a diving system holds great promise in improving the impact survivability of the system.
The authors would like to express their sincere gratitude to KAUST and the Splash lab for offering a place to conduct experiments and providing us with the necessary resources to conduct the research. Additionally, we would like to thank Prof. S.T. Thoroddsen and the High-Speed Fluids Imaging Laboratory for generously allowing us to use their water tank for the experiments, which was an essential part of the study. Without their support and assistance, this research would not have been possible.