Quasi-static and dynamic compression response of a lightweight interpenetrating phase composite foam

Quasi-static and dynamic compression response of syntactic foam (SF)–aluminum foam interpenetrating phase composites (IPC) is examined. Infusion of uncured syntactic foam (epoxy filled with hollow microballoons) into an open-cell aluminum network results in a 3D interpenetrating structure upon curing. The compression responses are measured at strain rates of ∼0.001/s and 1500/s. The dynamic experiments are performed using a split Hopkinson pressure bar set up. The role of volume fraction of microballoons on the response of IPC is examined in terms of yield stress, plateau stress and energy absorption under quasi-static and dynamic conditions. The response of IPC samples are also compared with those made using syntactic foam alone. The results show that the energy absorbed by the IPC foams under dynamic loading is consistently higher than that measured under quasi-static loading conditions. For all volume fractions of microballoons, the IPC samples have better compression characteristics when compared to the corresponding syntactic foam samples. The failure modes and mechanisms of SF and IPC foams are examined both optically (using high-speed photography) and microscopically and the underlying differences are discussed.