Accurate Bird Strike Simulation Methodology for BA609 Tiltrotor

Abstract

Bird strike incidents cause significant flight safety threats to aircraft safety, resulting in certification requirements of "continued safe flight and landing" following specified types of high-energy bird impact. The higher impact velocities for bird strikes that tiltrotor aircraft must survive underscores the need to develop more capable, validated analysis techniques. This paper presents the state-of-the-art bird strike simulation methodology developed at Bell Helicopter, based on the multimaterial arbitrary Lagrangian-Eulerian and smooth particle hydrodynamics techniques. The constitutive parameters of the bird model are calibrated to correlate the hydrodynamic pressure with available test data. The validated bird models are subsequently applied to simulate bird impacts with the BA609 tiltrotor structures for the most load-critical test conditions. The analytical models are validated for multiple test cases with different design architectures. The developed analytical tool is capable of accurately predicting structural failure modes and deformation for aircraft subjected to highenergy bird strike impacts.

Numerical and experimental investigation of the shock and steady state pressures in the bird material during bird strike

“…This paper focusses on the pressure peak by combining the use of dense meshes and forcing more output in time, to prove that the numerical model predicts the shock pressure quite well, independent of the contact area and without filtering. Additionally the large influence on the shock pressure of tilt- 35 ing the bird is also revealed. However, pressure measurements are by definition very local and therefore not representative for the behaviour on a larger scale.…”

Bird strike virtual testing for preliminary airframe design

“…An industry sponsored study (Tho et al 2008) involved the development of a novel numerical simulation methodology using the ALE and SPH methods for birds impacting on a tiltrotor flight vehicle cockpit nose, wing leading-edge and empennage. A slightly different approach was followed in the afore mentioned study, regarding the SPH bird modelling, in which a deactivation zone was added to release the bird particles that were no longer interacting with the impacted structure.…”

Bird Strike Virtual Testing Simulations and Results, for Preliminary Airframe Design Structural Optimization

“…Bird strike events have been heavily researched and many related studies are available in the public domain [3][4][5][6][7][8][9][10][11][12]. A vast variety of simulation models, many of which have been correlated with experimental results, have studied birds impacts on various types of aircraft components, in an effort to generate validated methodologies for bird strike modelling.…”

“…Time was normalized using the expression = , with t the actual time, Vo the bird's initial speed and D the diameter of the cylinder model, while pressure was normalized using the expression = , where the normalized pressure is that actual pressure versus a dynamic head comprising of the initial density and speed of the bird. The pressure results for this simulation were compared to Wilbeck's [5] experimental tests, as well as Heimbs FE model [10]. The above benchmarking procedure provided with enough confidence in the SPH modelling strategy and parameters adopted for the simulations performed on virtual LE structures.…”