Numerical Study Of Mechanical Properties Of Closed-Cell Metal Foams

Three dimensional Voronoi models are developed to simulate the microstructures of cellular solids and investigate the constitutive behaviors of closed-cell metal foams. Firstly, the basic conception and application of Voronoi tessellations are introduced. Voronoi models in conjunction with the finite element method can be used in the analysis of the mechanical behaviors of real foams because it gives a better representation of the morphological structure of foams. Voronoi models developed in this paper can be applied with the periodic boundary conditions, which is the key for the micromechanics analysis. The following parts of the constitutive behavior of closed-cell foams are analyzed with three dimensional Voronoi models: the mechanical property of linear elastic closed-cell metal foams, and the uniaxial behaviors of elastoplastic closed-cell metal foams.For linear elastic foams, Voronoi models are developed to analysis the mechanical behaviors of closed-cell foams under compressive loading. Dependence of the Young's modulus of the materials on the relative density and the fraction of cell-edges is evaluated through finite element analysis. Obtained results show that in the low density and high fraction of cell-edges regime the Young's modulus of random Voronoi foams can be well represented by periodic cubic foams, and is sensitive to the geometric imperfections inherent in the microstructure of foams.For elastoplastic foams, the responses of the materials due to the uniaxial mechanical loading are analyzed. When the materials are under compression, the plateau stresses exist in the stress-strain curves, which can also be found in experiments. Obtained numerical results show that the compressive plateau stress of the foams is less sensitive to the imperfections.