An investigation of stress redistribution caused by creep in a thick-walled circular cylinder subjected to axial and thermal loading

Abstract

A thick-walled tube was subjected to an axial load and a radial temperature distribution which caused thermal stresses. The creep strains and the eventual rupture times were observed and compared with conventional creep tests and theoretical analysis. Theory suggested and experiments confirmed that stress redistribution caused the overall strain behaviour to approach that for the mean axial stress and the mean radial temperature. Description of the experimental technique and apparatus includes a novel snd simple optical extensometer. Appendices contain a complete analytic treatment of the triaxial stress problem in a long thick tube in the presence of an arbitrary distribution of non-elastic strains, and a treatment of some conditions under which stress-redistribution calculations can lead to a "steady state" or "fully redistributed" stress pattern. A less rigorous theoretical treatment which ignores radial constraints is shown to lead to an under-estimate of the thermal stresses and of the time required for stress redistribution to occur.