Energy absorption during failure of layered metal foam/ceramic laminates

This study is concerned with the fracture behaviour of laminates made up of alternate layers of metal foam and ceramic. It is shown that the fracture energy of such material measured in flexure is broadly consistent with predictions from a model based on analysis of the plastic work done in deforming metal ligaments bridging between fractured ceramic sheets. Since the metal foams employed are rather brittle materials, the plastic work done in this mode, and hence the fracture energies of these laminates, were relatively low. Multiple cracking, which can enhance the work of fracture substantially was not observed with these laminates and this is also shown to be consistent with model predictions. The cell wall microstructure within the foam, which affects both local and global plastic deformation characteristics, is identified as an important factor. There is a need for metallic foams with cell walls exhibiting relatively high ductility and toughness.