Numerical simulation of a composite helicopter sub-floor structure subjected to water impact

This paper describes recent research activities on the design, numerical simulation and testing of a composite helicopter sub-floor structure with a novel approach to avoid skin breakage in the case of a crash on water. After the analysis of the structural behavior of current sub-floor designs in the case of water crash events IAI and ECD worked on a new design which was supported by numerical simulation work performed by DLR using the explicit FE-codes PAMCRASH. Finally a demonstrator sub-floor box was built to prove the concept in a component test that was performed at CIRA. In this paper the entire study is presented with a focus on the numerical crash simulations and the comparison with the corresponding test results from a purely vertical drop test on water. Finally, the validated simulation approach is used in a sensitivity study to investigate the behavior of the new sub-floor design in load cases with initial pitch and roll angles that could not be tested