Computational study of the composite panels of large thicknesses buckling taking into account through-the-thickness shear strains under compressive and shear loads

This paper is the first part of article series devoted to the computational study of thick composite panels buckling under compressive and shear loads taking into account through-the-thickness shear strains. In the first part of the study, an approximation is carried out taking into account the numerical solutions of the buckling problem. The first part presents a numerical study of orthotropic composite panels of a wide-body aircraft wing of large thicknesses, during which analytical dependencies are derived that determine the critical force for buckling under compressive and shear loads, taking into account through-the-thickness shear strains.

To determine the critical forces at which the panel buckles, the authors used a numerical modeling approach using the Finite Element Method (FEM) and Bubnov-Galerkin method (a method of aircraft structural mechanics). For this purpose, shell models of wing skin panels with orthotropic composite lay-up were made using a layer-by-layer modeling approach. A review of existing analytical dependencies for determining the critical forces for buckling of composite panels taking into account the through-the-thickness shear strains during compression was also carried out.

After validating the computational models, the authors conducted a series of virtual tests and analytical calculations for panels with different aspect ratios and thicknesses ranging from 1.8 mm to 24 mm in 2 mm increments. Based on the data obtained, the influence of through-the-thickness shear strains under compressive and shear loads was studied empirically, and an analytical relationship was obtained for assessing buckling of composite panels of large thicknesses under shear load.

The scientific novelty of this study is the identification of an empirical relationship for problems of composite panels of large thicknesses buckling under the influence of shear load, taking into account through-the-thickness shear strain.