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FROM:
Sigit Santosa (1), John Banhart (2) and Tomasz Wierzbicki (1)
(1) Impact & Crashworthiness Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
(2) Fraunhofer-Institute for Manufacturing and Advanced Materials, Bremen, Germany
“Bending crush behavior of foam-filled sections”, 1999, (publisher not given in the pdf file)
ABSTRACT: Bending crush behavior of thin--walled columns filled with closed-cell aluminum foam is studied exper- imentally and numerically. Non linear dynamic finite element code was used to simulate quasi-static three point bending experiments. Two strengthening mechanisms are observed. First, the aluminum foam filler retards inward fold formation in the compressive flange, therefore preventing the drop in load carrying capacity due to sectional crush. Then, the inward fold retardation changes the crushing mode from single stationary fold, a typical bending crush behavior of an empty beam, to multiple propagating folds. The progressive fold formations spread plastic deformations, thus dissipating more energy. These phenomena are captured from both experiments and numerical simulations. High bending resistance is also maintained when the foam is placed only locally in the zone of high bending moment. The concept of the effective foam length is then developed, and potential applications of foam-filled sections for crashworthy structures are suggested.
Also see:
Kremer, K., Liszkiewicz, A. and Adkins, J., “Development of steel foam materials and structures”, October 2004, Fraunhofer, Center for Manufacturing and Advanced Materials, Newark, Delaware
An extensive amount of study has been done that demonstrates the mechanical advantages of aluminum foam-filled structures. The bending resistance of an empty thin-walled beam typically drops significantly after relatively small deflections. The cause of this is due to inward fold formation on the compression surface which reduces cross sectional area at the crush zone. An example of this can be seen in Figure 32. The effect of aluminum foam filling on bending crush deformation can be seen in Figure 33. The aluminum foam minimizes local crushing of the beam causing the folds to propagate to adjacent sections. The multiplying of these plastic hinge lines increases the moment arm of the compression flange which produces a higher bending resistance.
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