Bending of Anisotropic Sandwich Beams with Variable Thickness

Abstract

In the stress analysis of anisotropic sandwich construction, a theory based on the assumption of constant thickness has been available for some time. With the design of high-performance spacecraft, aircraft, and sailboats, there is a trend to use variable- thickness sandwich structures to have proper guidance of airflow and further weight minimization. In this paper a theory is presented for the bending of linearly elastic sand wich beams with variable thickness. The sandwich structure consists of fiber-reinforced composites as the face sheets and honeycomb as the cores. In the analysis the face sheets are considered as membranes, the core is assumed to be deformable m transverse shear, and the contributions of the face sheets in resisting transverse shear together with the face- sheet membrane strains arising from the transverse shear deformation in the core are taken into account. The results indicate that analyses based on constant-thickness theory locally may lead to significant errors when applied to thickness-tapered sandwich beams with cores that are deformable in shear. The errors arise mainly from two factors: (a) the trans verse shear components of the membrane forces in the face sheets alter the transverse shears carried by the core; and (b) the face-sheet membrane strains arise from transverse shear deformation of the core.