Research of Weld on Axial Buckling Stress of Multilayer Combined Cylindrical Shells

Large welded steel tanks for oil storage (oil tank for short in following text) are usually constructed by welding together several varying thickness cylindrical shells. The generated welding residual stress and deformation may affect the buckling behavior of oil tanks. Learning the influence of welding residual stress and deformation on axial buckling helps accounting for discrepancy between elephant’s foot buckling critical stress and classic theoretical solution. A buckling analysis method considering welding residual stress and deformation is established. Inherent strain finite element method is illustrated as the proper method to simulate welding residual stress and deformation in buckling analysis and its detail setting procedures in ABAQUS are given. A small model cylinder is analyzed under three conditions (one circumferential weld only, one meridian weld only, and one circumferential weld with two meridian welds), leading to several important conclusions. One of these conclusions is that the extent to which welding residual stress and deformation reduces axial buckling critical stress depends on the weld type greatly. Then the established buckling analysis method is applied to an actual oil tank with patterned welds. Result shows that patterned welds decrease axial buckling critical stress significantly. At last several recommendations are given to decrease the effect of welding residual stress and deformation on axial buckling of oil tanks.