Optimizing sandwich beams for strength and stiffness

This article presents a method for minimizing structural mass by optimizing the geometry and core density of sandwich beams comprising composite face sheets and polymer foam cores, loaded in three-point bending. The optimization is constrained by both strength and stiffness requirements. All possible locations in design space which might be global minima of mass are identified, and it is shown that, for a global minimum mass, at least two constraints must be simultaneously active. Calculations for a typical set of material properties are performed with the result that, for a wide range of standard materials, a minimum-mass sandwich beam satisfying both strength and stiffness requirements utilizes low-density foam and is constrained by stiffness and indentation strength.