On the FE Modeling of Closed-cell Aluminum Foam
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Ó Springer 2006
On the FE modeling of closed-cell Aluminum Foam A. CZEKANSKI1, M. A. ELBESTAWI1,* and S. A. MEGUID2 1 Department of Mechanical Engineering, McMaster Manufacturing Research Institute, McMaster University, 1280 Main Street West JHE #316, Hamilton, Ontario, L8S 4L7, Canada; 2Engineering Mechanics and Design Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 KingÔs College Road, Toronto, ON, M5S 3G8, Canada *Author for correspondence (E-mail: [email protected])
Abstract. This investigation is concerned with the development of a multi-unit-cell which enables the modeling of the mechanical response of metallic foams subject to oblique loadings. The geometry of the cell was derived from careful observation of the foam morphology. The new closed unit cell is formed by the use of ellipsoids which are interconnected through a truncated pyramid. In this approach, we represent the morphology of closed-cell aluminum foams through the use of corresponding average uniform geometrical and mechanical properties. Extensive multi-unit-cell finite element analyses were conducted to examine the effect of key geometric parameters on the collapse load, normalized crush force versus deformation characteristics as well as the corresponding energy absorption. The numerical simulations were compared with crush test experiments involving different oblique loads. In spite of showing an initial stiff response, which is typical in idealized numerical models, the results revealed that the developed multi-unit-cell is able to simulate the crush behavior of closed-cell foams. Key words: aluminum, cellular material, closed-cell, crashworthiness, energy absorption, finite elements, metallic foam, unit-cell
1. Introduction Cellular materials possess a favorable combination of good mechanical and physical properties, while maintaining very low weight (6–35% of the parent material). They are excellent candidates for innovative future designs, in which low weight and high strength are strict design parameters. Special interest in this type of materials is currently devoted to investigating the potential use of metallic and non-metallic cellular materials to enhance vehicle crashworthiness. A large number of experimental and numerical investigations to characterize and model foam materials appeared in the literature. Some attention was also devoted to foam-filled structures. Gibson and Ashby (1997) presented an extensive coverage of the mechanical behavior of cellular structures. Of interest to this study is the work of Simone and Gibson (1998) who investigated cellular structure and mechanical properties of aluminum foams. They showed that the characteristics of an individual cell are closely related to the cell size. The anisotropy, orientation and wall slenderness of a large cell affect the mechanical properties more than that of a small cell. Based on a representative ellipsoid, the average properties were determined from the equivalent diameter, the diametersÔ aspect ratio and the absolute value of t
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