A proposed design chart to predict the inelastic buckling pressures for conical shells under uniform external pressure

The paper presents the theoretical and experimental results obtained when 15 machined circular section conical shells were tested to destruction under uniform external hydrostatic pressure. Three of the shells buckled elastically, but the other 12 buckled inelastically. Previous research has found that the inelastic buckling of such shells with small initial out-of-circularity has defied exact mathematical analysis, due to the fact that the initial out-of-circularity is very small and also of random distribution about the circumference. In this paper these results are used to provide a design chart that enables the inelastic buckling pressures of these vessels to be successfully determined. This design chart should prove to be more accurate, but less conservative, than existing design charts, so that the factor of ignorance is decreased and more reliability can be placed on the true factor of safety.