The deformation measurement and analysis on meso-structure of aluminum foams during shpb test

The split Hopkinson pressure bar (SHPB) is most widely used to measure the dynamic mechanical properties of materials. Such a testing methodology implies the assumption of uniform deformation during an impact test. However, the experimental verification of this assumption for aluminum foams has, as yet, been unreported. In this paper, a test system combining the SHPB with a high-speed digital camera was designed and constructed to study the problem. In the system, the synchronization between SHPB and the high-speed digital camera, the lighting, and the surface treatment of specimen are established. The deformation of meso-structure of aluminum foams during the SHPB impact was observed successfully; furthermore, the localized strains along the specimens were measured quantitatively. Experimental results show that the deformation is non-uniform; that means the assumption of uniform deformation for aluminum foam is not well satisfied. Therefore, a need exists for some modifications to characterize the dynamic mechanical properties of aluminum foams by SHPB.