Global/local analysis of composite plates with cracks

This paper presents a simple and accurate global-local method to calculate the static response of simply supported, composite plates with small cracks. 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 without the crack are augmented with a perturbation function, which is accurate for isotropic plates only, to account for the crack. The Ritz solution does not accurately satisfy the natural boundary conditions at the crack boundary. Therefore, a second step, local in nature, is taken in which a small area in the vicinity of the crack and encompassing other points of singularities, is discretized using a fine finite element mesh. The displacement boundary conditions for the local region are obtained from the global Ritz analysis. The methodology is applied for the local model including the crack. The proposed approach resulted in accurate prediction of stresses, with 85% savings in computational time and 92% in data storage for the analysis of composite flat panels. (C) 1998 Elsevier Science Limited. All rights reserved.