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Title: Experimental reference stress techniques for the prediction of creep deformations using lead alloy models
Author: Hyde, T. H.
ISNI:       0000 0001 2432 3056
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 1976
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TA Engineering (General). Civil engineering (General)