Gouging and Fracture of Engine Containment Structure under Fragment Impact

Abstract

This paper presents a numerical study of the failure response of an aircraft engine containment panel obliquely impacted by a titanium turbine fragment. A three-branch Bao-Wierzbicki fracture criterion is first calibrated for the target material (2219-T851 aluminum alloy) by performing tensile tests on round bars and upsetting tests on short cylinders. With this fracture model, the finite-element simulation of the impact test successfully captures the formation of an indentation/gouging channel on the proximal surface of the panel and the growth of a crack on the distal surface. An extensive parametric study is conducted on the effect of fracture criteria, mesh size, projectile pitch angles, and finite-element codes. Deficiencies of the Johnson-Cook and the constant critical strain fracture model are identified. It is found that the numerically predicted residual thickness and mass loss of the panel are sensitive to the magnitude of the pitch angle of the projectile. A large difference in calculated energy dissipation between ABAQUS and LS-DYNA is observed.