Bird Strike Modeling Using a New Woven Glass Failure Model

The bird strike impact problem is an increasing menace to the composite aerospace designer, especially since more aerospace components are being manufactured from composite materials. The LS-DYNA FE code is often used to model such an event as it can accurately represent the bird material behaviour and the contact between the bird and the structure. However, numerical simulations are usually accompanied by a parallel testing programme to validate the numerical simulations for some of these impact scenarios. The present paper described the implementation of an improved damage mechanics based material model to simulate the progressive failure of woven glass composites. A series of bird strike impacts on flat panels fabricated from low cost woven glass composite materials are used to validate the material model for practical composite component applications. The panels are modelled with shell elements only. The new material model can capture the strain rate enhancement to strength and strain observed for woven glass materials using a damage lag concept. A hydrodynamic model for the bird, based on 90% water and 10% air, is used to represent the behaviour of the bird for all impact scenarios considered. The bird is heterogeneous in nature, however, a uniform material behaviour is assumed with a geometry based on a 2:1 length: diameter ratio with a cylindrical body and spherical end caps using mesh less Smooth Particle Hydrodynamic (SPH) techniques. Appropriate contact definitions are used between the bird and the composite panel. The simulations results are compared to experimental results and conclusions drawn.