The hybridization of laminates, carried out using reinforcing fibers of a different kind in each layer, represents a very interesting solution from a design point of view. Mechanical behavior of hybrid laminates is highly influenced by their inhomogeneity which involves relevant values of shear deformability, so the first-order shear deformation theory (FSDT) is needed to evaluate their mechanical behavior. The optimal configuration of laminates is a relevant aspect of the laminates design mainly with reference to buckling phenomena. In the present paper, the determination of the optimal arrangement of hybrid laminates to get maximum buckling loads is analyzed for rectangular, simply supported, flat laminates under biaxial compression and shear. Using the FSDT in conjunction with the Rayleigh-Ritz method, buckling loads of laminates are obtained by an energetic algorithm as a solution of a standard eigenvalue problem. Moreover, damage phenomena produced by a large number of microcracks can strongly affect the mechanical response of the structure and the value of the maximum buckling load. In this work the relationships proposed by Laws and Brockenbrough [1] are used to model the damage phenomenon and are associated to the FSDT and the Rayleigh-Ritz method to obtain the change in the buckling load.
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