Stress Analysis of Post-Buckled Sandwich Panels

The paper presents a method to assess stresses in sandwich plates with periodic microstructure in the post-buckling region. The fundamental assumption is that the microstructure is linear elastic and von Karman non-linearity is present only at macro-, i.e. panel-scale. This enables response evaluation by equivalent homogenous continuum with constant stiffness properties. It is shown that the homogenization cancels shear-induced, odd-terms in microstructural field variables such as displacements and stresses. These are of fundamental importance when strength of the panel must be assessed. The localization approach utilised here neglects the actual position of the microstructure and thus is able to capture only the maximum values of these stress fluctuations. The validation of the present approach is carried out with 3D FE analyses and a good agreement is shown. The shear-induced periodic stresses are of fundamental importance when the strength in the post-buckling region is assessed based on linear elastic basis.