Energy absorption and deformation characteristics of a closed-cell Al foam, ALPORAS, were investigated under medium impact velocities ranging from 3 to 30 m/s. Uniaxial compression tests as well as indentation tests, using flat-end and spherical-end punches, were conducted. Experimental results show that the absorbed energy per unit displaced volume of the material increases with increasing velocity of the projectile. The projectile geometry shows significant effect on the energy absorption characteristics as well as the deformation mechanisms. Due to the near-zero plastic Poisson's ratio of the foam, deformation is confined only to the material directly beneath the indenter with very little lateral spread with the cells at the perimeter of the indent getting sheared. These results are compared with those obtained under quasi-static testing conditions with varying strain rates. The morphology of the impact zone is studied and correlated with the impact parameters. The mechanisms of deformation in this velocity regime are explained. The velocity dependence of deformation characteristics and energy absorption of the closed-cell foam under dynamic indentation are presented.
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