Mathematical modelling of creep in weldments using the Cosserat theory of plates and shells
Mathematical modelling of creep in weldments using the Cosserat theory of plates and shells
Long term problems arising from creep deformation occur frequently in industry. In the power generation industry, for instance, knowledge of the high temperature performance of plates and pipes containing weldments is of particular importance, since the majority of plant failures are associated with weldments. One mode of failure identified by metallurgists is called type IV cracking, and this mode occurs close to the weld in material which has been softened by the welding process.
This thesis extends the models of a weldment developed by Nicol(1985) and Hawkes(1989), which are based on the Cosserat theory of plates and shells.
The ultimate aim of this investigation is to predict the time to failure of weldments under applied loads. In order to achieve this goal we introduce the basic concepts of Continuum Damage Mechanics into both the Cosserat model introduced by Nicol and the alternative approach suggested by Hawkes. The lifetimes of a welded plate comprising the parent material, low and high temperature heat affected zones and weld metal, are calculated for both methods, for values of the parameters associated with type IV cracking. It is found that the corresponding solutions from each model display similar characteristics for the initial strain rates but the calculated rupture times can differ significantly.
A different Cosserat model of a plate, in which the assumed stress distribution is zero on the top and bottom surfaces, is next presented. Finally, we investigate the behaviour of a V-shaped weld, obtaining results which imply that the presence of the angled interfaces reduces the lifetime of the weldment.
University of Southampton
Newman, Michael Geoffrey
421515a0-efae-473b-8d9f-5b5751379a51
1993
Newman, Michael Geoffrey
421515a0-efae-473b-8d9f-5b5751379a51
Newman, Michael Geoffrey
(1993)
Mathematical modelling of creep in weldments using the Cosserat theory of plates and shells.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Long term problems arising from creep deformation occur frequently in industry. In the power generation industry, for instance, knowledge of the high temperature performance of plates and pipes containing weldments is of particular importance, since the majority of plant failures are associated with weldments. One mode of failure identified by metallurgists is called type IV cracking, and this mode occurs close to the weld in material which has been softened by the welding process.
This thesis extends the models of a weldment developed by Nicol(1985) and Hawkes(1989), which are based on the Cosserat theory of plates and shells.
The ultimate aim of this investigation is to predict the time to failure of weldments under applied loads. In order to achieve this goal we introduce the basic concepts of Continuum Damage Mechanics into both the Cosserat model introduced by Nicol and the alternative approach suggested by Hawkes. The lifetimes of a welded plate comprising the parent material, low and high temperature heat affected zones and weld metal, are calculated for both methods, for values of the parameters associated with type IV cracking. It is found that the corresponding solutions from each model display similar characteristics for the initial strain rates but the calculated rupture times can differ significantly.
A different Cosserat model of a plate, in which the assumed stress distribution is zero on the top and bottom surfaces, is next presented. Finally, we investigate the behaviour of a V-shaped weld, obtaining results which imply that the presence of the angled interfaces reduces the lifetime of the weldment.
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Published date: 1993
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Local EPrints ID: 462504
URI: http://eprints.soton.ac.uk/id/eprint/462504
PURE UUID: c0a2b5df-1da7-4b6d-a038-f93c916224be
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Date deposited: 04 Jul 2022 19:10
Last modified: 16 Mar 2024 18:56
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Michael Geoffrey Newman
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