Representative unit-cell models for open-cell metal foams with or without elastic filler

Representative unit-cell models were developed for open-cell metallic foams in order to predict their effective elastic moduli and the failure strengths. Two different open-cell metallic foams were considered. One was just open-cell foam and the other was open-cell foam filled with an elastic material. The models were based on the metallic frames consisting of edges of tetrakaidecahedron. The filling material was modeled as elastic foundation to the tetrakaidecahedral frames. The frame structure of the unit-cell was analyzed using the finite element (FE) method. The failure strength was determined when the vertices of edges became plastic hinges under the assumption of elastic-perfectly-plastic material behavior of the metallic material. Both elastic modulus and failure strength were computed using a single step of FE analysis without any iterative or incremental procedure. In addition, a very small number of FEs was used. As a result, the unit-cell was computationally very efficient. In order to assess the representative unit-cell models, experiments were also conducted. The experimental data agreed very well with the predicted values of both stiffness and strength.