Abstract:Combined shear-compression tests and simulations were performed on a closed-cell aluminum foam over a wide range of loading angles in order to probe their yield behaviors under biaxial loading conditions. Combined shear-compression tests were carried out by using a pair of cylindrical bars with beveled ends. The yield surfaces were experimentally measured and compared with various theoretical yield surface models. The cellular structures of closed-cell aluminum foams were modeled as tetrakaidecahedrons and their biaxial crushing behaviors were simulated by the finite element method. The results show that, yield initiates from the stress-concentrated corners in the specimens under combined shear-compression loading and the stress distribution is no longer uniform at the specimen/bar interfaces. In the range of cell sizes studied, the larger the foam cell size is, the higher the yield stress is. Aluminum foam density is found to be the dominant factor on its mechanical properties compared with the cell size and is much more significant in engineering practice.

Key words: combined shear-compression; closed-cell aluminum foam; yield surface; biaxial loading; yield behavior