An evaluation of the errors in the yield surface for a rotationally symmetric thin shell due to neglecting transverse normal stresses and shell curvature

An estimate has been made of the errors introduced in the plastic analysis of rotationally symmetric shells by the neglect of transverse normal stress σz, and the ratio of thickness to the radii of curvature in comparison to unity. It is shown that the latter effect will generally be negligible and that the more important factor is that due to σz. An example of a complete sphere under internal pressure is considered, and the further effect of moving the pressure onto the centre line examined.