Buckling strength of cylinders with a consistent residual stress state

The sensitivity of metal cylinder strength to geometric imperfections is well known. Because different imperfection forms and different amplitudes have quite different effects on cylinder strength, there has been a long search for the 'most serious' imperfection, constrained by the fact that this imperfection must be, in some sense, reasonably likely to be detected in a real structure after construction. The 'worst' imperfections currently known are far from practical. The search for practically useful and credible modes of imperfections has led to this study of the geometric imperfections arising from misfits of construction. Imperfections in the form of residual stresses have only rarely been investigated, and the challenges facing a rigorous treatment of them have often not been faced. This paper adopts a rigorous treatment technique to investigate residual stresses and their effect on the axial compression buckling strength under elastic conditions. It achieves this by considering consistent stress and displacement fields arising from local geometrical incompatibilities, and adopting their consequent geometric imperfections. The calculations of the strength of imperfect shells with residual stresses are compared with corresponding calculations for the same imperfections but with the residual stresses "annealed" out of the analysis. The results show that consistent residual stresses generally appear to strengthen a thin shell relative to the corresponding strength with only geometric imperfections present.