| In this study, the edge effects of composite laminates are investigated mathematically. The presence of stress singularities at the ply interfaces along the free edges is studied. The importance of determining all terms, including interlaminar stresses, in investigating the failure of composite plates is also shown. The simple composite plate, the pin-loaded composite plate, and the bolt-loaded composite plate are analyzed three-dimensionally.;A new "slice" model is developed to simulate the simple composite plate. Three-dimensional finite element analysis is performed with the "slice" model to verify the accuracy of the 20 node isoparametric element. The same stress analysis technique is subsequently performed to study the more complex pin- and bolt-loaded laminate problems. This method determines the entire stress state for each of the three problems.;A failure initiation model is developed and used to predict the failure initiation of the pin- and bolt-loaded composite plates. The model is used to determine the failure initiation modes: Matrix cracking, fiber breakage, and delamination. Experiments are undertaken for comparison with predicted results. Excellent correlation is achieved between predicted results and experimental data.;The effect of geometric parameters is also studied. The investigation provides a method to predict all failure modes by taking into account stress singularities at the free edge, using three-dimensional finite element analysis, and applying a proper failure analysis. |
