Simplified sublaminate analysis of composites and applications

An accurate estimate of interlaminar stresses is crucial to understanding as well as predicting many delamination related damages in composite materials. Simplified analytical models … the ply-by-ply bending, the sublaminate bending, and the sublaminate membrane models with decreasing level of complexity are developed to obtain these stresses. These models are based on a bending theory developed earlier. This theory incorporates all the essential physical effects and appears to be an adequate model for predicting the behavior of individual layers in equilibrium. In order to assess the accuracy of these models, three problems are solved: the stress induced in the free edge region of a (0, 90) s laminate in uniform extension, the stress analysis of a compression specimen with end tabs, and the analysis and design of a doublecrack-lap shear type fracture specimen. The results of the free-edge problem are in excellent agreement with the existing numerical solutions, analyses of previously tested compression specimens provide a plausible explanation of observed behavior, and the double-lap fracture specimen behaves as designed. The proposed models are suitable to parametric design-related studies, and according to the need a specific model can be more appropriate.