Elastic stability of cylindrical shells with weld depressions

Metal silos and tanks are subject to axial compressive stresses in their cylindrical shell walls. The buckling strength is very sensitive to geometric imperfections in the wall. The most regular and well-defined imperfection is the local depression adjacent to a circumferential weld, caused by the plate rolling process and shrinkage of the weld. This paper examines the elastic buckling strengths of thin cylindrical shells under axial compression, with imperfections arising at circumferential welded joints. The effects of the welded joint depression amplitude, the shell radius-to-thickness ratio, a change of shell plate thickness at the weld, and internal pressurization are all examined. The study is confined to cylinders with a radius-to-thickness ratio in excess of 100, as thicker shells are rare for these structures. It is shown that a welded joint depression is one of the most deleterious practical imperfection forms currently known.