Elasto-plastic Creep Deformations of Axisymmetrical Shells

Abstract

This paper is concerned with the numerical analysis of elastoplastic creep deformation of thin shells of revolution under an axisymmetric load with applications to pressure vessels. The mathematical theory of an elasto-plastic creep as it applies to thin shells of revolution undergoing considerably large deformations is developed. The basic differential equations derived for incremental values are numerically solved by a finite difference method, and the solutions are obtained by integration of the incremental values. As a numerical example the problem of elasto-plastic creep deformations of pressure vessels important to practical use is treated. It is shown that in elastoplastic creep deformations of thin shells such as usual pressure vessels the difference between solutions from a linear theory and those from a nonlinear theory becomes large, therefore the nonlinear theory should be employed. The elasto-plastic solutions from the prediction method agree well with experimentally determined values for pressure vessel heads by Findlay and others.