Dynamic Response Analysis of Bird Strike on Aircraft Windshield Based on Damage-modified Nonlinear Viscoelastic Constitutive Relation

Damage-modified nonlinear viscoelastic constitutive equation and failure criterion are introduced and the three-dimensional incremental forms are deduced based on the updated Lagrangian approach. A simple tensile test model and a split Hopkinson pressure bar model are built to verify the accuracy of the subroutine implemented within the non-linear finite element program LS-DYNA. A numerical model of bird strike on windshield is established to study the responses of windshield under three different bird velocities at three sites. The bird is represented by a cylinder with a hemisphere at each end and the contact-impact coupling algorithm is used in this study. It is found that the implemented subroutine can properly describe the mechanical behavior of polymethyl methaerylate under low and high strain rates and large deformation, and can be used validly.

Simulation on Collision of Bird with Windshield by Using MCA

The collision process of a flying bird and the aircraft windshield was simulated by using movable cellular automata ( MCA) method to improve the structure design of aircrafts. The simulation results show that the whole strike process is performed in 4. 8 ms,the critical strike velocity for an aeronautic glass windshield is 360 km/h,the windshield vibrates and deforms in the collision,and after absorbing the kinetic energy,its temperature increases. The simulation results coincide with the experiment data better. It is clear that MCA method has more advantages than the usual methods of continuum mechanics.

Design of aircraft structures against threat of bird strikes

In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software PAM-CRASH is employed to conduct bird strike simulations, and a coupled Smooth Particles Hydrodynamic（SPH） and Finite Element（FE） method is used to simulate the interaction between a bird and a target structure. The SPH method is explained, and an SPH bird model is established. Constitutive models for various structural materials, such as aluminum alloys, composite materials, honeycomb, and foam materials that are used in aircraft structures,are presented, and model parameters are identified by conducting various material tests. Good agreements between simulation results and experimental data suggest that the numerical model is capable of predicting the dynamic responses of various aircraft structures under a bird strike,and numerical simulation can be used as a tool to design bird-strike-resistant aircraft structures.

Mass and performance optimization of an airplane wing leading edge structure against bird strike using Taguchi-based grey relational analysis

Collisions between birds and aircraft are one of the most dangerous threats to flight safety. In this study, smoothed particles hydrodynamics(SPH) method is used for simulating the bird strike to an airplane wing leading edge structure. In order to verify the model, first, experiment of bird strike to a flat aluminum plate is simulated, and then bird impact on an airplane wing leading edge structure is investigated. After that, considering dimensions of wing internal structural components like ribs, skin and spar as design variables, we try to minimize structural mass and wing skin deformation simultaneously. To do this, bird strike simulations to 18 different wing structures are made based on Taguchi’s L18 factorial design of experiment. Then grey relational analysis is used to minimize structural mass and wing skin deformation due to the bird strike. The analysis of variance(ANOVA) is also applied and it is concluded that the most significant parameter for the performance of wing structure against impact is the skin thickness. Finally, a validation simulation is conducted under the optimal condition to show the improvement of performance of the wing structure.

A numerical model for bird strike on sidewall structure of an aircraft nose

In order to examine the potential of using the coupled smooth particles hydrodynamic （SPH） and finite element （FE） method to predict the dynamic responses of aircraft structures in bird strike events, bird-strike tests on the sidewall structure of an aircraft nose are carried out and numerically simulated. The bird is modeled with SPH and described by the Murnaghan equation of state, while the structure is modeled with finite elements. A coupled SPH-FE method is developed to simulate the bird-strike tests and a numerical model is established using a commercial software PAM-CRASH. The bird model shows no signs of instability and correctly modeled the break-up of the bird into particles. Finally the dynamic response such as strains in the skin is simulated and compared with test results, and the simulated deformation and fracture process of the sidewall structure is compared with images recorded by a high speed camera. Good agreement between the simulation results and test data indicates that the coupled SPH-FE method can provide a very powerful tool in predicting the dynamic responses of aircraft structures in events of bird strike.

Numerical simulation of a rotary engine primary compressor impacted by bird

In order to examine the process of a rotary engine primary compressor impacted by bird, a finite element model of a bird impacted on plate is developed with the explicit code PAM-CRASH. The smooth particles hydrodynamic （SPH） method is used to simulate the bird because of the SPH method showing no signs of instability and correctly modeling the breaking-up of the bird into particles. Good agreement between the simulation results and experimental results indicates that the numerical method of bird strike used in the present paper is reasonable. Then a rotary engine primary compressor impacted by three different configurations bird named straight-ended cylinder bird, quadrangular bird, hemispherical-ended bird are investigated using the numerical simulation method. It is found that the whole process of bird strike sustained about 3.5 ms and the bird is slashed by blade during the strike. The geometry configuration of bird affected the displacement and von Mises stress of some blades severely, just because the breaking bird＇s mass is affected by the bird＇s configuration. In the event of bird striking on the site of＂up＂some blades may develop plastic deformation and it is very adverse for the safety work of the engine.

Coupled Shell-Material Point Method for Bird Strike Simulation

In a bird strike, the bird undergoes large deformation like flows; while most part of the structure is in small deformation, the region near the impact point may experience large deformations, even fail. This paper develops a coupled shell-material point method （CSMPM） for bird strike simulation, in which the bird is modeled by the material point method （MPM） and the aircraft structure is modeled by the Belytschko-Lin-Tsay shell element. The interaction between the bird and the structure is handled by a particle-to-surface contact algorithm. The distorted and failed shell elements will be eroded if a certain criterion is reached. The proposed CSMPM takes full advantages of both the finite element method and the MPM for bird strike simulation and is validated by several numerical examples.

Integrating small mammal community variables into aircraft–wildlife collision management plans at Namibian airports

Understanding ecosystems within and around airports can help to determine the causes and possible mitigation measures for collisions between aircraft and wildlife.Small mammal communities are an important component of the semi-arid savanna ecosystems of Namibia,its productivity and its ecosystem integrity.They are also a major direct attractant for raptors at airports.The present study compared the abundance and diversity of small mammals between Namibia’s 2 main airport properties(Hosea Kutako International Airport and Eros Airport),and among areas of land used for various purposes surrounding the airports.A total of 2150 small mammals(3 orders,11 species)were captured over 4 trapping seasons.Small mammal abundance was significantly higher at the end of the growing season than during the non-growing season.The grass mowing regimen in current management plans at the airports resulted in a significant reduction of small mammal abundance at Hosea Kutako during the non-growing season only,thus indicating that annual mowing is effective but insufficient to reduce the overall abundance of mammal prey species for raptors.Small mammal numbers were significantly higher at Hosea Kutako Airport compared to the cattle and game farming land surrounding the airport,while no differences in small mammal densities or diversity were found for areas with different land uses at and surrounding Eros.The study suggests that the fence around Hosea Kutako provides a refuge for small mammals,resulting in higher densities.It also indicates that different surrounding land use practices result in altered ecosystem function and productivity,an important consideration when identifying wildlife attractants at airports.