Coupling Of MPM With Shell And Its Application In Bird Strike Simulation

Bird strike becomes a serious threat to the safety of the aircraft,and takes an important place in the aircraft certification process.Bird strike is a strongly nonlinear process,in which the bird undergoes extreme deformation while the aircraft structures may be destroyed.Besides experimental studies,there are three most established numerical approaches to study this problem: the Finite Element Method(FEM),Arbitrary Lagrange Eulerian(ALE)and Smooth Particle Hydrodynamics(SPH)method.However,none of them is free of disadvantages: the FEM encounters fatal problems of mesh distortion,the ALE is rather complex in capturing boundary and convection calculating,and the SPH is somewhat time consuming due to neighbor searching.There is no generally accepted uniform approach to bird strike simulation.The Material Point Method(MPM)avoids the abovementioned shortcomings of both the FEM and ALE methods,and shows advantages of computational efficiency and stability over the SPH method.It has been widely applied to the problems involving extreme material deformation.The MPM is employed to model the bird in this paper.An aircraft is mainly composed of thin-walled structures,so that the shell finite element is efficient and accurate to model these structures in small deformation.Hence,a shell element is incorporated in our MPM3 D code,and coupled with MPM particles based on a particle-to-surface contact algorithm.To fully take advantages of both the FEM and MPM,the adaptive finite element material point method is extended to bird strike simulation,in which the distorted and failed shell elements are converted to MPM particles adaptively.The proposed approach is first validated by several numerical tests,and then used to simulate a bird strike on an aircraft wing leading edge structure.