Stresses and deformations in egg-shaped sludge digestors: discontinuity effects

In the first part of this study [J. Eng. Struct. 23 (2001) 1365-1372], deta iled results for stresses and deformations throughout a hydrostatically-loa ded egg-shaped sludge digestor were developed on the basis of the membrane hypothesis for shells. However, and as is well-known, such results are gene rally unreliable around the junctions of the shell components making up the digestor. A significant amount of bending and shearing will occur in the v icinity of these junctions. In this paper, a simplified but reasonably accu rate approach for quantifying discontinuity effects is developed for genera l shells of revolution of a certain variation of thickness along the shell meridian, and applied to the present problem of the 3-region egg-shaped dig estor shell, to yield explicit closed-form results for discontinuity, and h ence net, stresses throughout the digestor. These results, being very gener al (all parameters are kept arbitrary), enable a quick and reasonably accur ate estimate of stresses in egg-shaped digestors of the type considered, an d will thus be useful to the structural analyst and designer. Any desired p arametric studies may also be conducted on the basis of these analytical re sults. Numerical results are presented, enabling some observations to be ma de and design recommendations proposed for egg-shaped digestors. (C) 2001 E lsevier Science Ltd. All rights reserved.