New hybrid foam materials for impact protection

The present paper investigates the dynamic compression and impact behaviour of a new class of open-cell Ni/Al-hybrid metal foams (nickel strengthened aluminium foams) in comparison to pure aluminium foams. In order to determine the characteristics of the pure aluminium and Ni/Al-hybrid foams, dynamic compression tests using a classical split Hopkinson pressure bar have been performed at strain rates up to 5000 s−1. Whereas the pure aluminium foams show only slight strain rate sensitivity, the hybrid foams are highly strain rate sensitive. The stress strain characteristics show a change in the deformation behaviour of the foams from bending dominated failure under quasi-static compression to a failure mode induced by microinertia effects under dynamic loading with additional stretching. As a fact of this additional stretching the hybrid foams are able to dissipate more energy under dynamic loading. Further ballistic impact tests have been performed on foam sandwich panels at impact velocities of 300 m/s. The hybrid foams show a significant improved ballistic protection performance especially in the case of elastomeric fillings. The paper outlines the possible application of Ni/Al-hybrid foams as crash absorber, security panels in case of blast and ballistic impact.