Influence of stiffeners on the buckling behaviour of composite panels subjected to non-uniform edge loads

Abstract

Analytical methods for calculating the buckling loads in laminated panels often assume uniform edge loads without any openings, overlooking real-world conditions with diverse non-uniform edge loads and varying cutout sizes. This study aims to explore the buckling behavior of composite panels with and without stiffeners under different non-uniform edge load distributions by developing a robust and computationally efficient finite element (FE) formulation. Buckling loads are determined for different plate aspect ratios, number of stiffeners under various non-uniform edge-loading cases. Furthermore, it addresses the effects of different layup schemes and stiffener eccentricities.The analysis employs a 9-noded heterosis plate element and a compatible 3-noded beam element, incorporating shear deformation and rotary inertia for both the plate and stiffeners. Additionally, due to the non-uniform stress distribution in the stiffened panels, a unique dynamic technique has been implemented to account for the stability performance by employing two sets of boundary conditions. The study demonstrates that maintaining stiffener eccentricity (est) within the range of 2.0 to 3.0 notably improves buckling strength depending on the type of edge loads.