Imperfections in Cylindrical Shells resulting from Fabrication Misfits

This paper presents part of a rigorous numerical study of the geometry changes in cylindrical shells due to localized fabrication misfit and the associated consistent residual stress field. The search for practically useful and credible modes of imperfections has led to this study of the geometric imperfections arising from misfits of construction. These are treated here by using a geometrically nonlinear analysis to study the effect of a mismatch in geometry at a point or a seam in a cylinder, or alternatively to explore the role of weld shrinkage in the formation of geometric imperfections. The imperfect geometries arising from these misfits are demonstrated, and some simplifications are given so that their shape may later be used in methods for characterizing imperfection patterns that can be applied to measurements of structures in service. It is found that the geometrical changes are essentially linear for most of the shrinkages considered.