WIT Transactions on Modelling and Simulation vol:55 pages:3-15
WIT Transactions on Modelling and Simulation
Computational Methods and Experimental Measurements edition:6 location:La Coruña date:2-4 July 2013
This study concerns the elastic response of a flexible open cell polyurethane foam and a complex foam in which an interpenetrating network is made by introducing a second material into the pores of the open cell foam. The elastic properties are investigated by means of experimental compression tests and FE-modelling work.
Compression experiments were performed to determine the mechanical properties of the different foam types including a study of the pronounced sample size effect based on Onck et al. (2001). The results indicate that this sample size and preparation effect have to be taken into account in order to obtain valuable results. A design of experiments was set up to determine the influence of cell size and foam density on the stiffness of the cellular materials.
In order to build a FE-model which represents the real foam topology as good as possible, the cellular architecture of the open cell foam was characterized using stereo-microscopy and CT-imaging. In this way cell size, strut length, type of cell faces and shape anisotropy were determined. FE-models of the open cell foam were build based on the Kelvin cell and Weaire-Phelan structure and allowed to study the influence of density, cell size and anisotropy. Surface evolver algorithms were applied to minimize the surface energy of the different unit cells (Brakke 1992). This intermediate step produced a FEM-topology with a remarkable resemblance to the real cellular structure. The results were in good agreement with experimental values and literature results (Gong et al. 2005).