WATER IMPACT OF METALLIC AND COMPOSITE MATERIAL STRUCTURES EXPERIMENTAL TESTS AND NUMERICAL SIMULATIONS ADOPTING THE ALE APPROACH

摘要

Water im pacts in em ergency are likely to have tragic consequences for the passengers of helicopters. Most of the pass ive safety devices de veloped for helicopter crashworthiness are designed for ground im pact. When impacting a solid or a soft surface, impact loads are rather different and ther efore energy absorption devices developed for ground impact are not effective du ring a water im pact. In order to collect reliable data for numerical models validation, water im pact drop tests were carried out: an Alum inium alloy and a Carbon Fibre Reinforced Plastic panel, si milar to modern aircraft skin panels, were mounted on a specific test device and tested. Im pact decelerations and deformations of the panels were m easured. Afterwards, a num erical m odel of the tests was worked out. The Arbitrary Lagrangian Eulerian approach was ad opted to model the fluid region. Eventually, a close experimental-numerical correlation was obtained for both th e panels in term s of impact dynamics, decelerations and deformations. The main features of the event and the differences between the i mpact behaviour of the two panels are discussed and failure of the com posite panel was investigated. Guidelines for further investigations are also drawn.