Limits of analytical models of sandwich structures for optimization

Abstract

Current advances in the structural optimization of aircraft structures have led to the introduction of sandwich panels into the optimization process. This study attempts to extend the possibilities of sandwich optimization by proposing an analytical model which predicts the homogenized properties of a sandwich panel with a honeycomb core and CFRP skins. The model is based on a combination of Classical laminate theory and a 1-D beam model of the honeycomb core. The finite-element equivalent of tensile and shear tests is used to validate the proposed model on a broad range of core geometries with different combinations of core thickness, wall angle, cell elongation, and cell wall thickness. The results of 425 different geometries showed the overall precision of the proposed model, highlighted effects in the behavior of the core that drive the sandwich properties further from the predicted values, and suggested which parts of the model are suitable for optimization and where are their limits of applicability.