Structural sandwich panels can be considered as a special type of composite laminate where thick, lightweight and compliant core material separates two thin, stiff and strong face sheets. Sandwich panels transfer bending and shearing load very effectively, but at the same time they offer limited resistance towards application of transverse loads, see e.g. Zenkert [
] or Allen [
]. A commonly used method of overcoming the problems associated with concentrated transverse loading is to introduce core inserts of higher strength and stiffness. This usually solves the problem of local reinforcement, but it also introduces new interfaces between materials of very different elastic properties.