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Comparative Study of Progressive Damage Prediction of a Countersunk Bolted Joint Using Continuum and Discrete Damage Modeling Approach



Two approaches have been developed to perform blind and recalibrated analyses of composite laminated plates with an open and a filled countersunk hole subjected to remote static loading. The first approach is based on a continuum damage mechanics (CDM) model, with the application of LaRC04 as the damage initiation criterion and an energy driven softening model to describe damage evolution. Failure event is determined elementwise based on a mesh characteristic length based on the crack band model in order to ensure its energy dissipation independence of the mesh size. Because of the presence of the localized stress concentration near a countersunk hole, fiber orientation dependent matrix cracks can be initiated and the resulting intensified stress field can promote delamination initiation and propagation at a ply interface. To enhance the modeling fidelity for discrete damage characterization at a critical region of a countersunk hole, the second approach based on a hybrid modeling strategy is applied where the inclined portion of the countersunk hole is characterized by CDM and its straight portion of the hole is described by a discrete crack network (DCN) model using a phantom paired crack modeling approach. A comparative study of both approaches is performed through the static failure prediction of the open and filled countersink hole tension specimen. Both the applicability and accuracy of the hybrid approach are demonstrated via its application for static failure prediction of open and filled countersink hole specimens subjected to compression.

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