Higher-order finite element for sandwich plates

A finite element model for the analysis of sandwich plates with laminated c omposites facesheets is developed. In the model, the facesheets are represe nted as Reissner-Mindlin plates and the core is modeled as a three-dimensio nal continuum in which the through-thickness representation of the displace ment fields is of a mixed form. That is, the u and v deflections are cubic functions of z, whereas w is a quadratic: function of z. This representatio n allows accurate modeling of a wide range of core types (honeycomb and foa m) and in particular core materials that have low in-plane stiffness compar ed to the transverse stiffness. Also, these through-thickness trial functio ns allow an accurate representation of transverse shear and normal stresses . The presented model provides a powerful general tool for the analysis of sandwich plates; transverse normal and shear stresses can be determined exp licitly at the core/facesheet interface. Also, because of the core model ad opted, good accuracy is obtained when large differences in transverse vs in -plane core stiffness is present, as well as for cases in which the core st iffness changes rapidly in the plane of the plate. The capability of the mo del is illustrated with several examples.