Modeling of Delamination in Composites

Stacking sequence, number of plies, and geometry of the composite structure have significant impact on the strength and reliability of the structure. The most detrimental failure mode in composite structures is delamination. Modeling of delamination failure is, therefore, a very important technique for predicting the reliability of composite structures. A modified crack closure technique was used in determining the driving force for crack propagation and branching of laminated composites at the interfaces. Mixed mode fracture parameters, G_I for the opening mode, G_II for the shear mode, were calculated using the technique for two typical composite structures; namely a composite laminate subjected to tensile loading, and a curved composite laminate subjected to bending. Results of these analyses give a better understanding on the crack growth behavior of these structures, and therefore, provide insight in the composite construction for improved design of the structures.