With the increase in air travel, the recent occurrences of birdstrikes on aircraft pose a major threat to human life; hence, there is a need to develop aircraft structures with a high resistance to such occurrences. According to the Federal Aviation Regulation (FAR 25.571) on Damage-Tolerance and Fatigue Evaluation of Structure (Amdt. 25-96), an airplane must be capable of successfully completing a flight during which likely structural damage might occur as a result of impact with a four-pound (1.8 kg) bird at sea-level cruise velocity or 0.85 percent of cruise velocity at 8,000 feet (2,400 m). Since the actual physical testing of a birdstrike is expensive, time-consuming, and cumbersome, this paper presents a methodology, based on the use of analytical finite element modeling and analysis, to certify an aircraft for a birdstrike. In actual physical testing for birdstrikes the mass of the bird might not be accurate and hence for certification purpose the computational modelling technique is more accurate and standardizes the certification procedure. The modeling and simulations are carried out as follows: the bird is modeled using the smooth particle hydrodynamics (SPH) technique in the LS-Dyna nonlinear finite element code. To validate this model, birdstrikes are carried out on rigid and deformable plates. The results, including displacement, Von-Mises stresses, forces, impulse, squash time and rise time, are obtained from the simulation, and non-dimensional values are plotted and compared with results from the test data. The detailed CAD geometry of the leading edge of an aircraft is modeled in CATIA V5. Meshing, connections, and material properties are then defined in the Altair Hypermesh 9.0 program. The results obtained from the birdstrike simulations on this leading edge are compared to data from the experiments, and the process is validated. Parametric studies are carried out by designing the aircraft leading edge for different values of nose radius and by assigning appropriate thickness values for leading-edge components and impacting the SPH-modeled bird at different velocities. The methodology and results obtained from simulation can be utilized in the initial design stages as well as for “certification by analysis” of an aircraft for birdstrike requirements as per federal regulations.

This content is only available via PDF.
You do not currently have access to this content.