Study of The effect of thickness and initial geometric imperfection of cylindrical composite shell on the buckling behavior in axial pressure

Today, composite cylindrical shells extensively, have been used in aerospace to increase the performance of the structures. Experience has shown that, when the shells are under compressive loading, Buckling phenomenon will be the most important factor in structural failure. Therefore, the main objective of this research was to study the buckling behavior of composite shells and effective parameters in occurrence of buckling. For this purpose, the finite element simulation by ABAQUS software has been used. First, the estimation of the buckling force for an experimental specimen occurred by using three analyses, including: linear buckle, nonlinear static and dynamic, to compare with experimental findings. Results indicated that the nonlinear static and dynamic analysis, were able to estimate the actual buckling force. The estimation accuracy with respect to the experiment results is about 3~7 percent. After validation process, specimens with different thickness and initial geometric imperfections have been studied and buckling force was measured by using linear buckling and nonlinear static analysis. Finding showed that even slight geometric imperfections, especially for low thickness of shell, could extremely reduced the real buckling force. As a result, high sensitivity of composite shells to initial geometric imperfections, will lead to an unreliable estimation of the buckling force, if there is not enough knowledge of these geometrical imperfections.