Local Buckling Strength of Steel Foam Sandwich Panels

In this paper a design method for the compressive capacity of sandwich panels comprised of steel face sheets and foamed steel cores is derived and verified. Foamed steel, literally steel with internal voids, provides the potential to mitigate many local stability issues through increasing the effective width-to-thickness of the component for the same amount of material. Further, steel foams have exceptional energy dissipation and deformation capacity. A design methodology for the compressive capacity of steel foam sandwich panels (plates) is needed to facilitate application of such panels and in the civil engineering domain. Winter’s classical effective width expression was generalized to the case of steel foam sandwich panels. The generalization requires modification of the elastic buckling expressions to account for shear deformations. Further, an equivalent yield stress is introduced to provide a single parameter description of the yielding behavior of the steel face sheets and steel foam core. The provided analytical expressions are verified with finite element simulations employing brick elements that explicitly model the steel face sheets and steel foam cores. The closed-form design expressions are employed to conduct parametric studies of steel foam sandwich panels with various face sheet and steel foamed core configurations. The studies show the significant strength improvements possible with steel foam sandwich panels when compared with plain steel sheet/plate. The design expressions and related parametric study provide insights on the optimal balance between face sheets and core. Given the success in defining optimal targets the obvious next step is assembly and testing of full-scale steel foam sandwich panels. This will complement existing efforts on material characterization of steel foam itself. This work is part of a larger effort to help develop steel foam as a material with relevance to civil engineering applications.

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