Survey of numerical approaches to analyse the behavior of a composite skin panel during a water impact

Water impacts may have tragic consequences for the passengers of helicopters. Most of the passive safety devices developed for helicopter crashworthiness is designed for ground impact. The loading that characterizes the impact with hard and soft surfaces is different and therefore energy absorption devices developed for ground impact are not effective during a water impact. Various researches focus on the use of composite materials for aircraft and helicopter fuselage. In this paper, in particular, it is investigated the behavior of a composite panel during the impact with water and the approaches to study the event by means of finite element codes. In order to collect reliable data for numerical model validation, water impact drop tests were carried out. A sample panel, made with a Carbon Fiber Reinforced Plastic material similar to those used for modern aircraft skin panels, was manufactured. A specific test device was created and used in the tests. Impact decelerations and deformation of the panel were measured. Numerical models of the tests were created. Meshless approaches were used, in addition to Lagrangian and Eulerian Finite elements, to model the water region. Eventually, a close experimental–numerical correlation was obtained for each model in terms of impact dynamics, decelerations and composite panel deformation. The main features of the event and the differences between the four numerical approaches were discussed. Guidelines for further investigations were also drawn.