Buckling of multiple discrete composite bundles in the elastomeric foundation of a curvature-morphing skin

Abstract

A short introduction to curvature-morphing skins is given. The studied structure consists of outer hybrid layers (undergoing large curvature alterations in operation) with unidirectional discrete composite bundles embedded in an ethylene–propylene–diene rubber foundation. This work focusses on the crucial aspect of compressive behaviour along these bundles. In order to achieve a high performance, it is essential that the bundles do not reach their stability limit prior rupture due to exceeding the strength of the structure. Specimens are manufactured and tested in an appropriate set-up under almost real boundary conditions. A finite element unit-cell is implemented and validated. The boundary conditions and the manufacturing tolerances of the hybrid layer are investigated with respect to bundle-buckling. Finally, failure maps depending on key geometry parameters indicate a clear distinction between an out-of-plane and an in-plane buckling mode whereas the latter results in lower critical strains.