Metal Foams and Porous Metal Structures (Eds. J.Banhart, M.F.Ashby, N.A.Fleck), pp. 283-288, 1999

INFLUENCE OF MICRO- AND MESO-TOPOLOGICAL PROPERTIES ON THE CRASH-WORTHINESS OF ALUMINIUM FOAMS

T. Daxner, H.J. Böhm, F.G. Rammerstorfer

Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria


Abstract - Metallic foams can be compacted at a relatively constant stress level which qualifies them for energy absorption applications. Their mechanical behaviour is influenced by imperfections caused by the foaming process. Spatial variations in the cell size distribution and imperfect cell wall geometries are studied as examples for such imperfections. Using 2D finite element unit cell models the interaction of different model topologies and cell wall deformations is examined. The topologies include hexagonal cell arrangements, big cells surrounding clusters of small cells and "rings" of small cells surrounding big cells. Imperfections on the cell wall level comprise sinusoidal wiggles and curved cell walls.
By simulation of large strain compressive deformations the interaction of non-uniform cell size and cell wall imperfections is examined, and their mutual influence on the crash-worthiness of the cellular structure is assessed. From such simulations conclusions can be drawn with respect to production strategies in order to fulfil quality requirements for metallic foams used in energy absorbing elements.


(hjb,991012)