Some fracture mechanics properties in high-velocity impact-damaged aluminium plates

The paper describes the results of an experimental programme aimed at the evaluation of the fracture mechanics properties of high velocity, about 6 km s(-1), impact-damaged aluminium plates, 2219-T851. The energy of the impacts was the ballistic limit, i.e. large bumps were produced but the plates were not perforated. Test were carried out to evaluate the residual stress field in the impact-damaged area, the static resistance of the plates in the presence of a through crack and the crack propagation rate of a through crack located at the centre of the impact-damaged area. The results of the tests clearly show that the mechanical properties of the material remain practically unchanged after the high-velocity impact. Furthermore, by taking into account the geometry of the bumps, the mean crack propagation rate of a defect can be predicted quite accurately.