Modeling the properties of closed-cell cellular materials from tomography images using finite shell elements

• Published in: Acta materialia 2008-11, Vol.56 (19), p.5524-5534
• Main Authors: Caty, O., Maire, E., Youssef, S., Bouchet, R.
• Format: Article
• Language: English
• Subjects: Cellular; Closed cell cellular materials; Computer simulation; Engineering Sciences; Finite element method; Finite element models; Hollow sphere structures; Materials; Mathematical models; Shell meshes; Shells; Three dimensional; Walls; X-ray tomography
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2008.07.023

Closed-cell cellular materials exhibit several interesting properties. These properties are, however, very difficult to simulate and understand from the knowledge of the cellular microstructure. This problem is mostly due to the highly complex organization of the cells and to their very fine walls. X-ray tomography can produce three-dimensional (3-D) images of the structure, enabling one to visualize locally the damage of the cell walls that would result in the structure collapsing. These data could be used for meshing with continuum elements of the structure for finite element (FE) calculations. But when the density is very low, the walls are fine and the meshes based on continuum elements are not suitable to represent accurately the structure while preserving the representativeness of the model in terms of cell size. This paper presents a shell FE model obtained from tomographic 3-D images that allows bigger volumes of low-density closed-cell cellular materials to be calculated. The model is enriched by direct thickness measurement on the tomographic images. The values measured are ascribed to the shell elements. To validate and use the model, a structure composed of stainless steel hollow spheres is firstly compressed and scanned to observe local deformations. The tomographic data are also meshed with shells for a FE calculation. The convergence of the model is checked and its performance is compared with a continuum model. The global behavior is compared with the measures of the compression test. At the local scale, the model allows the local stress and strain field to be calculated. The calculated deformed shape is compared with the deformed tomographic images.