Mimicking the loading adaptation of bone microstructure with aluminum foams

Nature has always been considered as a source of inspiration for scientists and engineers to create or mimic new materials with interesting properties. In this study, we draw inspiration from the loading adaptation of trabecular bone microstructure, which exhibits a graded distribution of porosity and cell size, with axially elongated cells. Using conventional foaming processes, we designed, manufactured and tested two different types of bone-inspired aluminum closed cell foams, aimed at mimicking the loading adaptation feature: the first type, characterized by a directional gradient of pores (i.e. along the length of the specimens) and the second type, characterized by elongated pores by hot rolling process. Micro-Computed Tomography (mu CT) is used to compare the morphological properties of aluminum foams and those of bones. Geometry-based Finite Element (FE) models are built from the mu CT images and validated by means of experimental data. Using image analysis techniques, virtual models have been created to expand the range of data and get further insight into the structural behavior of the material. This study shows that closed cell aluminum foams can be produced with biomimetic uniaxial mechanical properties in the low strain regime, by controlling their relative density and the axial orientation of cells.