Multiscale Deformation of Open Cell Aluminum Foams

Abstract

This article reports the results of experimental studies of the deformation of open cell aluminum foams under monotonic and cyclic compression. The multiscale nature of compressive deformation is examined from individual struts to overall foam deformation. Stress-strain curves of individual struts are investigated using micro-tensile testing. Deformation localization (dislocation slip bands) in individual struts is discussed along with evidence of deformation bands at the macro-scale. The onset and propagation of deformation localization bands are elucidated via in situ imaging and digital image correlation (DIC) techniques that provide continuous mapping of strain fields across sample sections; the Gibson-Ashby model is then used to estimate the dependence of foam strength and stiffness on relative density and strut properties. Finally, foam fatigue behavior under cyclic behavior is also studied, and attributed to surface crack nucleation and propagation in individual struts at different fatigue stages. Micro-fatigue testing is also carried out on individual struts that are extracted from foam blocks.