Plastic Behaviour of Thin Cylindrical Pressure Vessels with Circular Cutouts and Radial Branches

Abstract

Pressure tests were performed on four thin cylindrical aluminium vessels with circular cutouts and cover plates, and on two vessels with radial branches. In all cases a fairly well defined ‘limit pressure’ was observed—corresponding to plastic deformation in the vicinity of the cutout or branch—together with a moderate increase in pressure as deformation proceeded, which may be interpreted as a moderately strong ‘geometry-change effect’. The limit pressures observed for vessels with cutouts agree well with a lower-bound analysis which is described in outline. In general the observed limit pressures fit in well with those observed by other workers for vessels of different proportions. Correlation of geometry-change effects is not so simple, but a fairly clear picture of trends emerges from the study. The question of appropriate geometrical parameters for correlation of results is discussed, and a suggestion is made for taking into account any ‘extra’ cross-sectional area at the junction weld.