Increase in ovality of uranium tubes due to creep under external pressure

Abstract

Abstract

The increase in ellipticity of a concentric slightly elliptical tube is theoretically investigated for the case of external pressure and radial temperature gradient when the creep rate is proportional to the stress and the constant of proportionality varies slightly between the principal axes.

The presence of a radial temperature gradient accelerates the increase in ovality due to initial ovality on the outer surface and that due to circumferential variation of strength (except after very small collapses) and decreases that due to initial inner ovality. Further allowance for circumferential variation in temperature, due to an insulated inner surface and to a uniform heat-transfer coefficient to a gas at constant temperature around the outer surface, reduces the increase in all cases.