Higher-Order Finite Element for Sandwich Plates

Abstract

A finite element model for the analysis of sandwich plates with laminated composites facesheets is developed. In the model, the facesheets are represented as Reissner-Mindlin plates and the core is modeled as a three-dimensional continuum in which the through-thickness representation of the displacement 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 representation allows accurate modeling of a wide range of core types (honeycomb and foam) and in particular core materials that have low in-plane stiffness compared to the transverse stiffness. Also, these through-thickness trial functions 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 explicitly at the core/facesheet interface. Also, because of the core model adopted, 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 stiffness changes rapidly in the plane of the plate. The capability of the model is illustrated with several examples.