Improvement of Axial Load Capacity of Elliptical Cylindrical Shells

摘要

By varying the thickness of the cylinder wall with circumferential position, the axial buckling capacities of homogeneous, isotropic cylindrical shells with elliptical cross sections are improved. The classic buckling stress relation for a uniform-thickness homogeneous, isotropic circular cylindrical shell is applied to cylinders with elliptical cross sections. It is assumed that this relation can be used to design the wall thicknesses of elliptical cylinders as a function of circumferential location to compensate for the negative effects of the variation of the radius of curvature with circumferential location. Three variable-thickness elliptical cylinder designs are proposed, and analytical expressions for the thickness variation, cross-sectional area, axial buckling stress, axial buckling stress resultant, and axial buckling load for each design are derived. Predictions from the analytical development are then compared with finite element analyses of the three designs. So-called small and large cylinders with three values of eccentricity are considered. The comparisons between the finite element results and the analytic predictions are quite good. It is shown that considerable improvement in axial buckling capacity can be achieved with the thickness-tailoring technique, and in some cases the axial capacity of the circular cylinder with the same circumference is achieved.