· Buckling and Nonlinear Analysis by Finite Element Method:
The ABAQUS software [14] has been used to provide finite element modeling. The models are 300 and 150 mm in height and 1.6 mm thick in tanks. In the modeling of multilayer composite cylindrical shell in ABAQUS software, used for the mesh of four-sided and four-node elements (S4R), which is a two-curved element and has the ability to analyze large strains. The loading and boundary conditions of the model are determined in the loading environment. To apply external pressure, the inner surface of the cylinder is first selected. The loading method is also such that uniform pressure is introduced into the tanks environmentally. The supporting conditions of the specimen are arranged in detail. The bottom part is tangential in the three radial, tangential, and axial directions. At the top, the specimens have only radial and tangential Constraint, and the axial movement is free. (Fig. 1) shows how to load and apply boundary conditions.