Compaction of metal foam subjected to an impact by a low-density deformable projectile

The deformation of a stationary foam block due to an impact by a foam projectile is analysed. Several combinations between the properties and geometry of the projectile and stationary block are used in order to reveal the characteristic features of deformation under the condition of decreasing velocity during the impact event. No details of the cellular geometry are analysed and it is assumed that the foam is a homogeneous material. The dynamic compaction of the foam block and projectile is described by a one-dimensional model. The model is based on the propagation of a strong discontinuity unloading wave when using the actual experimentally derived stress–strain curves for three aluminium based foam: Alporas with 9% relative density and Cymat foams with 9.3% and 21% relative density. Numerical simulations were carried out to verify the proposed model. It is shown that the strain distribution in the foam blocks significantly depends on the material properties and boundary conditions. It is shown that a more distinct boundary between the compacted and undeformed foam can be observed in the projectile while the strains in the stationary block usually decrease gradually with the increase of the distance travelled by the compaction wave from the interaction boundary. It is demonstrated that the proposed approach is capable of predicting the history and final strain distribution in the foam with sufficient accuracy.