Micro-mechanical and X-Ray micro-computed tomographical analysis of quasi-static three-point loading behaviour of closed-cell aluminium foam with and without epoxy-bonded aluminium face-sheet

A quasi-static three-point loading experiment of closed-cell aluminium foam without face sheet (CCA) and closed-cell aluminium foam with face sheet (CCAF) was performed. During the experiment, load-deformation curves of CCA and CCAF foams were monitored for varying span length and crosshead velocity. CCA and CCAF foam maximum loading capacity were around 283.41 N and 1633.76 N, respectively. The effect of facesheet on the morphological and elemental inhomogeneity was analysed and related to understand the foam failure behaviour. It was observed that the presence of high strength epoxy-bonded face sheet prevented the tensile zone fracture in CCAF foams as compared to CCA foams. Micro Computed Tomographical analysis showed adjacent undeformed cells of the fractured region of CCA foams. CCA foams showed ductile-brittle mode with brittle dominating failure mode. In contrast, CCAF foams showed the gradual pore deformation and mixed deformation mode with initial indentation followed by the core shear process. Microstructural, elemental, and phase analysis of the failed zone showed micro-cracks, micro dimples, and ridges present in the foam core's cell wall. Ca–Ti–Al precipitates and intermetallics were present in plateau and cell wall regions. These precipitates act as reinforcement to the cell wall's strength during compression (as in CCAF foams). However, in tensile loading zone, they acted as a centre of crack initiation (as in CCA foams).