The fatigue strength of sandwich beams with an aluminium alloy foam core

Sandwich beams with aluminium face sheets and an aluminium alloy foam core are tested in cyclic four point bend, and S–N fatigue curves are determined for the failure modes of face fatigue, core shear and core indentation. The operative failure mode is dictated by the relative fatigue strength of face sheets to core, and upon the geometry of the sandwich beams. Simple analytical models are developed to predict the fatigue strength for each of the competing failure modes, and a design map is produced to display the fatigue strength and mode of failure as a function of sandwich beam geometry.