Buckling analysis of composite lattice sandwich shells under uniaxial compression based on the effective analytical equivalent approach

In this paper, a new effective equivalent analytical approach is presented to compute the global buckling of composite lattice sandwich shells under uniaxial compression based on the first-order shear deformation theory (FSDT). The lattice core was transformed into a solid skin, as the middle skin of the sandwich shell by considering the transverse shear strains and the new force and moment effect analysis on the selected unit cell. The equivalent stiffness of the composite lattice sandwich shells is then calculated by superimposing the stiffness contribution of outer, middle and inner skins. Using the FSDT and Rayleigh-Ritz method, the related eigenvalue equations are solved, and the critical buckling load is obtained. Furthermore, a 3D finite element model is built using ABAQUS software for validation. For various test examples with different slenderness ratio, outer/inner thickness and ply stacking sequence, stiffener thickness and the number of unit cells, the efficiency and accuracy of the presented equivalent approach are confirmed by comparing the obtained results with FE and other work results. It is shown that for thick sandwich shells, the use of FSDT for determining their critical buckling load is necessary, more suitable and can give high computational efficiency.