ELASTIC-PLASTIC STRESS ANALYSIS OF SPHERICAL SHELL UNDER INTERNAL AND EXTERNAL PRESSURE

A thick-walled spherical shell made up of homogeneous material subjected to combined effect of internal and external pressure has been analysed. The objective of this paper is to provide guidance in designing the spherical shell so that collapse of spherical shell due to internal and external pressure can be avoided. The problem is based on elastic-plastic transition phenomenon and the solution has been obtained by using the concept of generalized strain measures and Seth's transition theory. The transition theory does not assume adhoc assumptions like incompressibility and yield conditions. The radial and circumferential stresses have been evaluated at the internal surface of the spherical shell for compressible as well as incompressible materials. It has been observed that the spherical shell of incompressible material requires a high pressure to start initial yielding in the shell as compared to the spherical shell of a compressible material. The results are derived numerically and shown graphically.