Testing and numerical simulation of water impact on amphibious aircraft composite panels influenced by stiffness configurations

As the demand for amphibious aircraft intensifies, the challenge of water impact has emerged as a critical technical hurdle impeding broader adoption. This research focuses on the water impact protection of amphibious aircraft composite panels (AACP) by designing three distinct AACP configurations with varied stiffness properties through the manipulation of stringer spacing and skin configuration. Employing a custom-designed apparatus and methodology for water impact simulation, this research accurately replicated the cabin's water impact load time-history curves on the AACP surface, achieving a reproduction error within 5 %. The dynamic response and damage characteristics of the AACP under water impact were analyzed using the 3D Hashin failure criterion and a cohesive zone model. The findings reveal that the proposed equivalent bending stiffness ratio (R_x,m) and the stiffness configuration analysis method are effective in evaluating responses such as deformation and strain. The configuration with a four-stringer sandwich skin panel (R_x,m=1.236) exhibited superior performance, reducing peak deformation and strain by up to 43.2 % and 50 %, respectively, compared to other configurations. In contrast, configurations with a low R_x,m demonstrated inadequate load-bearing capabilities and suffered transverse skin fractures during testing due to stiffness mismatches. Both simulation and experimental results confirm the pivotal role of stiffness distribution in energy absorption and damage modalities. This research provides essential insights for the design of lightweight, impact-resistant composite structures.