Benefits of metal foams and developments in modelling techniques to assess their materials behaviour: a review

A review assessing the relative benefits of metal foam core sandwich panels with respect to honeycomb, polymeric foam and truss cores has been conducted. It is noted that metal foams are able to combine low density with good bending stiffness and strength, making them attractive core materials for use in industrial applications (e. g. aircraft wing structures). The current modelling tools available for metal foams are also reviewed. These fall under three categories: analytical methods using dimensional analysis, finite element methods utilising a repeating unit cell, and finite element methods utilising the random Voronoi technique. It is noted that analytical methods do not take into account the effect of imperfections in the microstructure. Finite element methods utilising a repeating unit cell also fail to capture the natural variations in microstructure that are observed in most cellular materials. The effects of imperfections are discussed, and it is observed that these reduce the hydrostatic strength of foams by differing amounts. The Voronoi technique can produce a geometrically more realistic model of the foam structure than the other two methods. Finite element methods are also being developed that utilise a three-dimensional tomographic image of a real foam as the geometric description of the model and it is possibly here that the most exciting developments for the modelling of foams resides.