Effect of foam density on the imperfection sensitivity of aluminium foam sandwich panels under in-plane compression

Abstract

Aluminium foam sandwich panels are attractive lightweight structural components because they offer a good combination of low mass, stiffness, strength, and energy absorption. However, their in-plane compressive behaviour is still not fully understood, especially when the foam relative density and out-of-plane geometric imperfections are considered together. This study investigates how variations in the combinations of foam relative density and out-of-plane geometric imperfections influence the in-plane compressive response of these panels, with emphasis on strength, collapse mode, and post-buckling behaviour. These findings improve the understanding of the compressive performance and support more reliable use of these panels in lightweight structural applications.

Parametric studies were conducted to examine the in-plane compressive response of 200 aluminium foam sandwich panels with varying relative density and initial imperfection. For certain combinations, mode interaction was enhanced, producing a temporary increase in load carrying capacity. The resulting imperfection-dependent interaction windows do not vary monotonically with either parameter but instead reflect a balance between foam-core stiffness, and imperfection sensitivity. A sensitivity study also showed that plate modulus also has a role in the formation and extend of such mode interaction windows.

To support design decisions, a multi-objective performance framework was developed using imperfection tolerance, deformation mode stability, energy absorption, and mass efficiency. In addition, as a practical aid to similar panel configurations, a FE based predictive equation was developed to predict the normalized peak load in the higher imperfection regime.