Numerical modelling of mechanical behaviour of aluminium foam using a representative volume element method

In this paper a micromechanical modelling method is developed to investigate the mechanical behaviour of the aluminium foam. A new Representative Volume Element (RVE) model denoted as ORVE is proposed based on thin-walled close octadecahedron cells, and then finite element models of these ORVEs are developed for the numerical modelling of the mechanical behaviour of the aluminium foam. The developed numerical model is validated by comparing the computed stress-strain relationship to that from experiments from literatures. The effect of compressing air on the compressive stress is also investigated and it is found that it can be neglected. An intensive parametric investigation is consequently conducted to study the effect of cell size and relative density on the mechanical behaviour of the aluminium foam based on the ORVE model. It is found that the mechanical behaviour of the aluminium foam depends mainly on the relative density/porosity or the ratio of cell wall thickness to cell height. The size of the cell is found to affect the Young's modulus but not the yielding strength, and for the aluminium foam of the same porosity, the Young's modulus slightly goes up with the increase of cell height. It is also found that the mechanical behaviour of the foam is not sensitive to the strain rate. In addition, a relationship between porosity and mechanical properties of the foam is proposed based on the ORVE model.