Sandwich panels are composite structures which consist of two thin but stiff layers that are attached to a thick and low weight layer (called core). Sandwich panels are suitable for use in applications which needs a high stiffness to weight ratio. Sandwich panels are used in lots of industrials like traortation, navy, aerospace. Similar to other composite structures, use of sandwich panels are limited because of inaccurate estimation of their life service. Delamination is one of the damages that can decrease life service of these structures. In this thesis, for analyzing delamination in these structures, first different aspects of damages caused by delamination were studied and then by comparing techniques to model delamination, cohesive zone model was chosen. After investigating details of cohesive zone model, the model provided by ABAQUS software was chosen and accuracy of results for this model was studied by simulating some standard tests in this field. For investigating delamination in sandwich panels with industrial geometry and loading conditions, first by conducting some tests the necessary cohesive parameters were obtained, then simulations for analyzing two sandwich structures were performed. Finally effect of each cohesive parameter on results were studied. Comparing results obtained from tests and simulations done by cohesive zone model approach, verifies capability of cohesive zone model in analyzing delamination for sandwich panels. Keywords: sandwich panels, delamination, cohesive zone model, cohesive parameters
