Estudo analítico e numérico da flambagem de laminados duplo-duplo sob cargas axiais e de cisalhamento

Abstract

Double-double (DD) laminates, introduced in 2021 as an alternative to conventional quasi-isotropic laminates widely used in aerospace applications, consist of repeated sublaminates with two groups of balanced angles. These configurations offer greater design flexibility and ease of manufacturing, attracting growing research interest. This thesis presents closed-form expressions for the buckling analysis of carbon/epoxy DD laminate plates subjected to compressive and shear loads, considering various boundary conditions. For shear loading, the analysis focuses on long plates. An optimization strategy is also proposed to maximize shear buckling performance, using a design space based on commercially available carbon/epoxy pre-pregs. The closed-form solutions are derived from dimensionless stiffness matrices normalized by laminate thickness and Tsai’s modulus. A comparative buckling study with quasi-isotropic laminates is conducted, evaluating homogenization behavior and the effect of repetition count on coupling terms 𝐷16 e 𝐷26. To support the design process, an algorithm is developed to identify stacking sequences that maximize shear buckling loads. The algorithm incorporates Tsai’s modulus, the master ply concept, and the maximization of 𝐷22 as its primary criterion. Validation through finite element analysis shows that, for laminates satisfying homogenization conditions, differences in buckling loads remain below 8%, with consistent buckling modes. The algorithm successfully identifies near-optimal stacking sequences with a prediction error of 8.2%.