| Metallic foams are a new class of material which have the potential to be used in several diverse applications. However, they have yet to be fully characterized. In an attempt to rectify this, an examination of the mechanical properties of two commercially available aluminum alloy foams is made. In particular, an assessment of the role of cell morphology in governing the stiffness and yield strength is made. Two novel techniques have been employed to aid in this investigation. Strain mapping and x-ray computed tomography enable examination of the deformation of surface and internal cells, respectively. During uniaxial compression, deformation is localized in narrow bands having widths the order of a cell diameter, with the surrounding material remaining elastic. The ellipticity of a cell is influential in the formation of deformation bands; size does not appear to be a factor. Through this assessment, manufacturing strategies for good mechanical performance with affordable processing can be investigated.; As metallic foams have the potential to be used for lightweight structures, the bending performance of sandwich construction with thin cellular metal cores has been measured and simulated. A mechanism approach has been generated to characterize the predominant failure phenomena based upon collapse load criteria for face yielding, core shear and indentation. A previously developed constitutive law for the core material has been incorporated into numerical simulations. Comparisons have been made with the measured response. Initial discrepancies attributed to a core thinness effect were rectified by inputting core shear properties measured on materials having the same thickness.; Retention of the load capacity of sandwich beams in the presence of imperfections is a central consideration. To address this issue, sandwich beams with metallic foam cores have been tested in four point bending following the introduction of imperfections, created by indentation to varying degrees. The indents were located on both the compressive and tensile side of bending configurations. Finite element results compare favorably with experimental measurements of the load/deflection response, if debonding is not prevalent. Beams designed with face yielding as the dominant mode of failure demonstrate the greatest degradation in load capacity. |
