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Marie-Anne Lavoie Augustin Gakwaya - Laval University David G. Zimcik M. Nejad Ensan

Review of existing numerical methods and validation procedure available for bird strike modelling 14th ICCES Conference, Jan 3-8 2007, Miami, USA. Marie-Anne Lavoie Augustin Gakwaya - Laval University David G. Zimcik M. Nejad Ensan – NRC-IAR. INTRODUCTION.

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Marie-Anne Lavoie Augustin Gakwaya - Laval University David G. Zimcik M. Nejad Ensan

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  1. Review of existing numerical methods and validation procedure available for bird strike modelling14th ICCES Conference, Jan 3-8 2007, Miami, USA Marie-Anne Lavoie Augustin Gakwaya - Laval University David G. Zimcik M. Nejad Ensan – NRC-IAR

  2. INTRODUCTION • During the certification process, an aircraft must demonstrate its ability to land safely after being struck by a bird • Past experience has been to demonstrate this compliance through full-scale test • Bird models are generally developed based on tests data that are nearly 30 years old • Aim to summarize the steps involved in creating a bird model

  3. INTRODUCTION • THEORY of bird strikes and an analytical evaluation of the expected results • EXPERIMENTAL DATA that are currently available • Description of the three NUMERICAL BIRD MODELS one can use • Analysis of the RESULTS • Recommendations are made in the CONCLUSION regarding the best suitable method

  4. THEORY • High velocity bird impact Þhydrodynamic behavior • Event is divided into two stages: • Shock: Hugoniot pressure: • Steady flow: Stagnation pressure: • Equation of state

  5. EXPERIMENTAL DATA Most complete results: Wilbeck (1977) • Gelatin with 10% porosity • Density of 950 kg/m3 • Shape of projectile

  6. EXPERIMENTAL DATA

  7. EXPERIMENTAL DATA

  8. EXPERIMENTAL DATA Current work in bird testing • Best practice tends to tweak numerical model to fit test data from impacted aeronautical structures; • Down side of this general approach is that bird models are specific to their application; • Industries which have financed recent bird strike tests are not willing to make their knowledge public.

  9. NUMERICAL BIRD MODELS • Early stages of bird impact simulations, the bird was represented by a pressure pulse on the structure. • Three main modelling methods are currently available. They are: • the Lagrangian mesh; • the arbitrary Lagrangian-Euler (ALE) mesh; • the smooth particle hydrodynamics (SPH) method. • 1 kg bird travelling at 116 m/s impacts on a 0.50.5 m rigid square plate.

  10. NUMERICAL BIRD MODELS - Lagrangian • 500 hexahedral elements • Fluid-structure interaction controlled through contact between bird and target

  11. NUMERICAL BIRD MODELS - ALE • 19,000 hexahedral elements of equal length, width and height • Fluid-structure interaction controlled through *constrained Lagrange in solid

  12. NUMERICAL BIRD MODELS - SPH • 4600 SPH particles each weighing 0.224 gr (0.0005 lbs) • Fluid-structure interaction controlled through a node-to-surface contact between the bird and the target

  13. RESULTS - Lagrangian

  14. RESULTS - Lagrangian

  15. RESULTS - ALE

  16. RESULTS - ALE

  17. RESULTS - SPH

  18. RESULTS - SPH

  19. CONCLUSION • The comparison with the experimental data highlights the need for future bird calibration testing • The Lagrangian method is no longer suitable • ALE and SPH models compare well with the analytical predictions • Currently, the ALE method is a standard approach to bird impact modelling • The SPH method formulation works well and is still developing • We are working on an improved version of SPH method which will interact with a solid structure

  20. ACKNOWLEGMENTS • Laval University • National Research Council of Canada (NRC) • Consortium for Research and Innovation in Aerospace in Quebec (CRIAQ)

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