Modelling helicopter crashworthiness onto water using a coupled FE-SPH approach

Abstract

As part of the CAST European project, a full-scale water impact test of a WG30 airframe was carried out and vertical ditching Lagrangian approach FE model was performed. The first aim was to model the WG30 helicopter impact onto water using a coupled FE-SPH approach. The second aim was to address if a FE-SPH approach was able to provide the same level of accuracy than a FE-FE model and whether it was worth the increase in computational time. Firstly, a simulation of a simple rigid wedge impacting on water was run using a coupled FE-SPH code. A sensitivity analysis was carried out together with analytical and experimental validation which refined the SPH formulation and parameters that were used in the next stages. The next step concerned modelling a helicopter subfloor impact on water using a coupled FE-SPH to present a comparison between simulations: FE-SPH, FE-FE; and test. This model allowed further investigation coupling deformable FE structures with SPH. The FE-SPH approach dem onstrated being able to provide sensible deformation correlating with CAST component test. Finally, the simulation of a full-scale deformable WG30 coupled with SPH water was undertaken. It predicted 87ms of the impact event, doubling the previous FE-FE termination time. It was a pioneer simulation within this research field. Moreover, close agreement was found between simulation and test in terms of structural damage and data provided by the CAST project. The FE-SPH approach has demonstrated being able to provide sensible global deformation according to test. SPH and FE water formulations predict the same level of damage and deformation for the airframe and subfloor structures. The choice of FE over SPH, and vice versa, is subjected to the judgement of the analyst balancing the model needs.