GLOBAL LOCAL ANALYSIS OF COMPOSITE PLATES WITH CUTOUTS/

The study focuses on the development of a simple and accurate global/l ocal method for calculating the static response of stepped, simply-sup ported, isotropic and composite plates with circular and elliptical cu touts. The approach primarily involves two steps. In the first step a global approach, the Ritz method, is used to calculate the response of the structure. Displacement based Ritz functions for the plate withou t the cutout are augmented with a perturbation function, which is accu rate for uniform thickness plates only, to account for the cutout. The Ritz solution does not accurately satisfy the natural boundary condit ions at the cut-out boundary, nor does it accurately model the discont inuities caused by abrupt thickness changes. Therefore, a second step, local in nature is taken in which a small area in the vicinity of the hole and encompassing other points of singularities is discretized us ing a fine finite element mesh. The displacement boundary conditions f or the local region are obtained from the global Ritz analysis. The ch osen perturbation function is reliable for circular cutout in uniform plates, therefore elliptical cutouts were suitably transformed to circ ular shapes using conformal mapping. The methodology is then applied t o the analysis of composite plates, and its usefulness successfully pr oved in such cases. The proposed approach resulted in accurate predict ion of stresses, with considerable savings in CPU time and data storag e for composite flat panels.