A Numerical-Experimental Investigations on Crash Behaviour of Skin Panels during a Water Impact Comparing ALE and SPH Approaches

Water landings in emergency are likely to have tragic consequences for helicopters. Most of the safety devices developed to enhance helicopter crashworthiness have been designed referring to ground impacts and they might be not effective in case of water landings. At LAST, the crash labs of Politecnico di Milano, water impact drop tests were carried out to deepen the knowledge of the event dynamics and to collect reliable data to validate numerical models. The water impact behaviour of skin panels made of aluminium alloy was investigated, in particular the panel failure due to water impact pressure. Drop tests with several drop heights and different impacting masses were performed measuring accelerations of the test article. In the second part of the research, the tests were numerically reproduced adopting ALE and SPH approaches to model the fluid region. The numerical results were compared both ones to the others and to the experimental tests in terms of impact dynamics and data acquired. As a result, a satisfactory correlation was achieved and guidelines to model fluid regions adopting ALE and SPH approaches were drawn.