A Theoretical and Experimental Study of Failure Maps of Sandwich Beams with Composite Skins and Honeycomb Core

Failure maps of sandwich panels such as beam, plate and shell are of great importance in designing such structures. In this paper, failure maps of sandwich beams with composite skin and honeycomb core are obtained. The effect of transverse shear in skins and core and the effect of double walls of honeycomb core have been taken into account. Shear deformation of skins and core are assumed to be linear. By minimizing the potential energy equation, the shear deformation coefficients of core and skins are obtained. Axial stresses in skins and core are obtained in terms of these coefficients. Core is assumed to have orthotropic properties. Three point bending tests have been performed on some sandwich beam specimens. It is found that specimens for which failure load and its corresponding failure mode lie away from the boundary lines in failure map, there is a little difference between failure loads obtained from theories and experiments but this difference is more significant near the boundary lines due to combination of failure modes. In the case of transverse ribbon direction, the theoretical and experimental results are closer.