Preface Sandwich panels composed of thin face sheets and a core material constitute material-tailored structural components for fiber-reinforced polymer (FRP) composite materials. The FRP face sheets bear the bending moment while the core -usually a foam or honeycomb material -is subjected to shear. In civil engineering applications, the core material normally has to be reinforced due to large spans (e.g. in roof constructions) or heavy concentrated loads (e.g. in bridge construction). This

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... forcement consists of a core-integrated grid of FRP webs that bear the shear forces. The function of the core material is thus limited to the prevention of wrinkling in the compressed web or face sheet laminates. This type of structure is known as a cell-core sandwich. A major failure mode of sandwich structures is wrinkling of the compressed face sheets. This source of failure is well known and reliable models exist to predict the wrinkling load. Wrinkling, however, can also occur in the webs of cell-core sandwiches. Since this type of structure is still new and therefore not yet well investigated, models to predict wrinkling in the webs due to shear do not yet exist. Wrinkling is caused by the compression diagonal, which is crossed by a transverse tension stress field. The effect of such transverse tension stress fields on the wrinkling load of laminates is as yet unexplored. This thesis focuses on this phenomenon, which is of great importance for the reliable and economic design of cell-core sandwiches.