Low energy impact damage modes in aluminum foam and polymer foam sandwich structures

The energy absorption of an aluminum foam sandwich structure and a conventional polymer foam sandwich structure is similar for impacts ranging from 5 to 25 J. The polymer foam-based samples exhibit localized damage in the form of skin fracture and core crushing, but with negligible permanent out-of-plane deformation. In contrast, the aluminum foam-based samples show little fracture but exhibit extensive out-of-plane deformation radiating from the impact point. This deformation suggests that the impact damage could be more easily detectable in the aluminum foam sandwich structure. Surface strains are lower in the aluminum foam sandwich samples during post-impact loading in a single cantilever beam test, suggesting improved damage tolerance.