Investigation of nonlinear post-buckling delamination in curved laminated composite panels via cohesive zone model

The delamination in curved composite laminates is one of the main defects, especially in aerospace structures. To optimize the design of the delaminated composite panels under compression loading, accurate characterization of the effects of different parameters such as features of the initial defect, the curvature of the laminate, and layup stacking sequence on the post-buckling behavior play a significant role. In this research, after a comprehensive review on the main previous researches, by implementing a Cohesive Zone Model (CZM), the nonlinear post-buckling response of different curved laminated composite panels has been investigated in the presence of various single and multiple delamination growth. To validate the present modeling procedure, the obtained results are compared with the experimental and previous numerical ones. Then, a detailed parametric study is performed on the effects of fiber angle orientation as well as number, size, location and stacking sequence of delaminations with different sizes on the post-buckling behavior of curved laminates with various curvatures. Results show that, in the panels with short length of delamination, an unstable growth occurs. In the flat panel, the amount of this phenomenon and its effects on decreasing the postbuckling load capacity are much more than the curved panel. The obtained results of this study highlight the sensitivity amount of instability behavior of curved composite panels to curvature, layup, and delamination features. The conclusions are essential and beneficial in the stability analysis and damage tolerance design of curved composite laminates, which are commonly used in the aircraft structures.