Aircraft bird-strike events are very common and dangerous. Hailstone impacts represent another threat for aircraft structures. As part of the certification process, an aircraft must demonstrate the ability to land safely after impact with a foreign object at normal flight operating speeds. Since experimental studies can be cost prohibitive, validated numerical impact simulation seems to be a viable alternative. Modelling of these soft body impacts still represents a challenge, involving modelling of both the target and the projectile. Here the smooth particle hydrodynamics method (SPH), which has been used successfully in ballistic applications involving bird strike scenarios, is extended to hail impact. The paper thus presents the meshless SPH numerical method as a novel modeling approach. The method is applied to model bird and hail impacts which are problems that traditional FEM based modeling methods typically struggle to solve because of involved mesh distortion problems. The numerical results are then evaluated by comparing with the data collected during recent experimental tests. The data acquisition methods are also described and evaluated for applications where the short duration of the impact presents a challenge. The accuracy of the numerical results allows us to conclude that the models developed can be used in the certification and/or design process of moving (aircraft) and stationary (wind turbines) composite structures subject to bird and hail impact.
The paper describes recent progress on numerical simulation of soft body impact onto a fibre reinforced composite wing leading edge structure. The work is based on the application of non-linear explicit finite element analysis to simulate the response of composite wing structures under soft body impact loads. Soft body impactors such as gelatine (substitute bird) or ice (hailstones) are highly deformable on impact and flow over the structure spreading the impact load. Therefore, first benchmark simulations were carried out for soft body impact onto a rigid target. Soft body impactor was modeled using the Arbitrary Lagrangian-Eulerian (ALE) method. The results obtained using this impact model for different velocity were compared to the experimental test results in terms of local pressure, including Hugoniot and stagnation pressures, and global load to validate the accuracy of the model. Then, the impact of soft body onto a composite wing structures was described. A composite failure model which includes ply damage and interplay delamination model has been used to predict impact damage in the structure modeled using shell elements. The simulation tool predicts the impact damage in leading edge structure.
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