Low strain rate compressive behavior of high porosity closed-cell aluminum foams

Drop hammer experimental measurements are carried out tostudy the compressive behavior and energy absorption characteristics of highporosity closed-cell aluminum foam specimens subjected to low velocityimpact loading. The dynamic deformation behavior of the specimen is observedby high speed camera and the velocity attenuation of the drop hammer isrecorded. The results demonstrate that the aluminum foam has excellentenergy absorption capabilities under low velocity impact loadings, with itsdynamic compression behavior similar to that obtained under quasi-staticloading conditions. Finite element method (FEM) is employed to obtain stressdistributions in the drop hammer and foam specimen, with and without theeffects of friction on contact surface considered. The presence of frictionrestrains the transverse displacement of the contact surface, causing theobserved convex shape of the foam specimen. As the propagating period ofstresses in the specimen is far less than the attenuation duration time, thevariations of the stresses are similar to those under quasi-static loadingconditions and no obvious stress wave effect is observed. With the effectsof the friction on the contact surface accounted for, an analyticalcolliding model of the drop hammer-aluminum foam system is established. Thepredicted velocity attenuation is compared with both the experimentalmeasurements and FEM simulation results, with overall good agreementachieved. The effects of different impact velocities and mechanicalproperties of foam material on the attenuation process are discussed.