Different from conventional metal foams, the mixed open/closed cell characteristic of the sintered metallic hollow sphere (MHS) materials offers excellent specific stiffness and energy absorption capacity. Based on our experimental study on two types of MHS specimens we reported before, a theoretical model is presented here to predict the mechanical behavior of the MHS materials in large strains (i.e. in the plateau phase). It is anticipated that the HCP packing configuration dominates in the actual MHS material structure, so that this configuration is taken in the idealized model. Based on the hypothesis of a periodic repeatability of a representative block, the large deformation of hollow spheres compressed by rigid balls is numerically simulated to identify the characteristics of deformation mechanism. Then, a rigid-plastic analysis is adopted to model this large deformation mechanism and to predict the stress-strain behavior of the representative block. Thus, the variation of the stress with strain is obtained for the idealized material of certain relative density, resulting in a relationship between the average stress in large strains (i.e. the plateau stress) and the relative density of the actual material. The predicted stresses are found in good agreement with the experimentally measured characteristic stresses of the two types of MHS materials.

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