Large static deformation analysis of thin cylindrical shells with different moduli in tension and compression: An application in pressure hulls

Bimodular materials have different moduli of elasticity in tension and compression. In existing studies, the bimodular effect of materials is rarely considered due to the complexity of the analysis. This paper presents a theoretical study of large static deformation problems of thin circumferentially-closed cylindrical shells with bimodular effect in an underwater environment. First, the geometrical and physical equations of large axisymmetric deformation of bimodular thin cylindrical shells are established, and the total strain energy of the cylindrical shell is obtained. Based on variation principle, the Ritz method is used for the obtainment of the important relationship between external pressure and deformation. The numerical simulation based on ABAQUS also validates the analytical relation. As an application example, the underwater pressure hulls considering the bimodular effect and large deformation is analyzed. Results show that the bimodular effect change the stiffness of shells to some extent, thus leading to changes in deformation. The cylindrical shell is more sensitive to the bimodular effect at higher loads. In addition, the change of radius-to-thickness ratios of shells will strengthen bimodular effect on deformation while the change of length-to-radius ratios will influence the bending configurations of shells. In the design of pressure hulls, considering the bimodular effect will play a positive role in materials saving.