Water Impact of Helicopter Subfloor Panels

摘要

The hydroelastic structural response excited during helicopter ditching involves extremely complex physics to capture through analytical solutions. The Smoothed Particle Hydrodynamics (SPH) method has proven its suitability to represent free-surface flows, and when coupled with traditional Lagrangian Finite Element (FE) method enables water impact problems to be simulated with reasonable computational times. The water impact of thin aluminum and carbon fiber composite panels was chosen as a benchmark case to determine the accuracy of meshless methods to predict loads during water entry. Experiments were conducted using a servo-hydraulic water impact system with various impact conditions to support the validation of numerical models. High sensitivity was observed to the selected fluid equation of state and to the smoothing length factor. The FE/SPH models accurately predicted the loads experienced by the panels during water entry. Deformations of the panels were also consistent with experimental measurements although the accuracy of the predictions may be improved with a refined representation of the specimen restraints.