Experimental reference stress techniques for the prediction of creep deformation using lead alloy models

Hyde, T.H. (1976) Experimental reference stress techniques for the prediction of creep deformation using lead alloy models. PhD thesis, University of Nottingham.

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Abstract

It is necessary at the design stage to predict the creep behaviour of components and structures operating at high temperature. The direct calculation of the creep behaviour requires extensive material data for the long service lives of the components and engineering methods are needed to minimise the amount of data needed. This can be achieved in some cases by use of the so called Reference stress method and the objective of this work was the experimental prediction of the creep deformation of some components using developments of this idea. It has been achieved by the determination of Reference stresses from accelerated room temperature creep tests of lead alloy models.

Reference stresses, which characterise the creep response of components in relation to uniaxial tests, have previously been determined by calculation. Reference stresses determined by the new experimental methods have been compared with analytical predictions for beams in pure bending, cantilevers, thin cylinders and thin spheres under internal pressure. Acceptable agreement was found for the Reference stresses and consequent predictions of creep deformations. The method has also been used successfully to predict creep strains in a cylindrical pressure vessel with a hemispherical end.

The methods of chill-casting models from a lead-antimony-arsenic alloy have been improved and the material has been calibrated by constant and stepped load, uniaxial and biaxial (combined pressure and torsion of thin cylinders) tests. The creep strains cannot be characterised by separate. stress and time functions; a strain hardening law best describes its stepped load response; the von-Mises criterion gives accurate predictions of creep strains in the tension-compression quadrant but underestimates the creep strains in the tension-tension quadrant.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Creep behaviour, Reference stress method, Thermal stresses, Creep of lead alloys
Faculties/Schools:UK Campuses > Faculty of Engineering > Department of Mechanical, Materials and Manufacturing Engineering
ID Code:1718
Deposited By:Mrs K.J. Blore
Deposited On:17 Dec 2010 10:33
Last Modified:17 Dec 2010 10:33

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