Lattice Materials - failure mechanics and assessment of multifunctional applications

Over the past decade, a range of commercial metallic foams have been developed. These are mostly produced by the introduction of gas bubbles (e.g. hydrogen) into the melt. The bubble expansion process leads to random cellular structures, and minimisation of surface energy leads to a low nodal connectivity, with typically three to four struts per joint. The resulting mechanical properties are far from optimal due to the fact that the cell walls deform by local bending. This led to a search for open-cell microstructures which have high nodal connectivities and deform by the stretching of constituent cell members, giving a much higher stiffness and strength per unit mass. These cellular solids known as lattice materials also have potential for multifunctional applications as structural heat exchangers and shape changing structures.The principal aims of this project are to: (i) expand property space by new combinations of material and topology, (ii) model and measure the mechanical properties of lattice materials (stiffness, strength, toughness and fatigue resistance) as a function of topology, constituent material and imperfection, and (iii) explore multifunctional applications including morphing and active energy absorption capabilities. This study will lead to a fundamental pre-competitive understanding of the mechanics of lattice materials, and will provide a tool-kit for designing with lattice materials.