Thermal analysis of aluminium foam based on microcomputed tomography

Finite element analyses are performed in order to determine the effective thermal conductivity of closed-cell Alporas (R) foam and open-cell M-Pore (R) sponge. The investigated finite element models are based on high resolution micro-computed tomography images. The complex structures of the real materials are very well represented with this method. The dependence between the computed effective thermal conductivities and relative density is approximated with analytical scaling laws and linear regression models. Calculations in three perpendicular directions aim towards the investigation of a possible anisotropy. Furthermore, different model sizes are considered in order to estimate the representative volume for the effective thermal conductivity. The findings of this paper indicate that a unit cell containing at least 3 cells in each direction or 27 cells in total is sufficiently large to determine the effective thermal conductivity of these cellular materials. Note that both Alporas (R) and M-Pore (R) exhibit the same qualitative behaviour (i.e. a linearly increasing thermal conductivity with rising relative density) at different absolute levels. More precisely, Alporas (R) exhibits an approximately two times higher effective thermal conductivity than M-Pore (R).