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Intra-Inter Crack Band Model (I2CBM) as a Prediction Tool for Open Hole and Filled Hole Failure Analysis of Composite



Intra-inter crack band model (I2CBM) is a unified approach for modeling various intralaminar and interlaminar progressive damage and failure events in polymer matrix composites. The progressive damage and failure formulation used in this method accounts for various crack planes, modes and their mutual interactions as observed in experiments. By carefully selecting the material properties, 3D elements in I2CBM formulation can be adapted for modeling individual lamina elements or to model the interface delamination elements. The input parameters used for the I2CBM predictions are either obtained from coupon level tests or calibrated against relevant laminate level test data. A path for communication between the intralaminar and interlaminar failure mechanisms are enabled in the model to overcome some of the limitations associated with homogenized element modeling and also helps to capture complex interactions in a physically correct manner. A non-local crack tracking method is added to the analysis tool to keep a global record of the development of matrix cracks in the model and it ensures a certain spacing between adjacent cracks as observed in experiments. The above two features equips the analysis method to be able to capture various failure modes observed in composite laminates including the growth of splitting cracks in 0 layers within a laminate. These capabilities are validated against open hole tension and filled hole tension test data of 27 ply and 36 ply laminates with countersunk holes. The effect of bolt pretension on the filled hole failure analysis is also presented and the failure mechanisms are discussed.

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