Effects of Size and Location of Initial Delamination on Post-buckling and Delamination Propagation Behavior of Laminated Composites

In this paper, buckling, post-buckling, and delamination behavior of composite laminates subjected to axial compression was studied. First, compression tests were performed for composite laminate specimens with through-width delamination and the history of buckling and delamination propagation was measured. Next, the tests were simulated using two-dimensional finite-element models. A geometrically non-linear post-buckling analysis was performed for the finite-element mesh seeded with small amount of geometric imperfection based on eigenmodes. The growth of delamination due to sub-laminates buckling was simulated using the cohesive zone modeling. The analysis results were compared with the test results for the verification of the numerical model. Then, the analysis results were examined to study the relation between geometric parameters of initial delamination and buckling loads and post-buckling delamination propagation behavior of the composite laminates. The effects of different sizes and locations of initial delamination on the delamination behavior were systematically investigated. It was found that the buckling loads, mode shapes, and the delamination growth behavior are affected by the geometry variation of pre-included delamination. The long and shallow initial delaminations prompt local buckling the deep delaminations induce global buckling mode.