Simulation of a rigid plate hit by a cylindrical hemi-spherical tip-ended soft impactor

This work is concerned with the dynamic impact response simulations of a soft model bird projectile striking a flat rigid panel. A hemi-spherical cylindrical tip-ended soft material was adopted to model a bird traveling with an incident velocity of 116, 197 and 253 m/s. The constitutive modeling of the soft impactor was studied. The diameter and the length of the impactor were 11.4 and 22.8 cm, respectively, and the weight of the impactor was 1.8 kg (i.e. 4 lb). Based on J. S. Wilbeck’s AFML-TR-77-134’s report, the material properties of the soft impactor was modeled to be similar to the properties of a real bird and the shear strength of the bird was neglected. The non-linear finite element code – LS-DYNA was used in this study to analyze the problem numerically. Three different formulation approaches, i.e. the Lagrangian (LAG), Eulerian (EUL) and the Arbitrary Lagrangian Eulerian (ALE) methods, were adopted in the present numerical analysis. Simulated dynamic pressure at the center of impact surface was computed based on three methods proposed. Simulated dynamic pressure versus time relationships were compared with Wilbeck’s test result and also checked against the stable stagnation pressure for the present study. Good results were found with the use of the coupled-field ALE method to obtain the dynamic pressure evolution after impact initiated and also the stable stagnation pressure. The results based on the LAG and EUL methods were reported to be less accurate.