Thermal ratchetting of polycrystalline metals with inhomogeneous thermal properties

Abstract

The study readdresses a theory of superplastic behaviour induced by cyclic temperature for certain classes of polycrystals and composite materials, originally analysed by Anderson, Bishop and Greenwood in the 1960s. Adopting the same kinematic assumptions as these authors, we show that the effects of varying residual stress fields were not fully taken into account in their analysis. A new analysis is given of the problem originally solved by Anderson and Bishop, the cyclic strain growth of uranium when subjected to a large temperature variation and small-applied stress. The resulting solution retains superplastic behaviour, but at rates that are significantly lower and with a changed variation with temperature amplitude. This suggests that related problems would benefit from re-evaluation in the light of this work.

Keywords:

• ratchetting
• cyclic thermal loading
• residual stresses

Acknowledgement

The first author first became aware of the Anderson and Bishop solutions when working with Roger Anderson on the modelling of a similar phenomena in the irradiation induced swelling of structural steels [24]. In recent years, following an interest in the thermal properties of metal matrix composites, it became clear that the solutions have been extensively applied to problems in material science.

The authors wish to thank Roger Anderson for assistance in this work. The work for this study was partly supported by a Leverhulme Emeritus Fellowship to the first named author and by EPSRC grant EP/G004676/1, which are gratefully acknowledged.

Notes

1. Copies of references [1–3] are available, with the permission of the National Archive for [1,2], for downloading from: http://www.le.ac.uk/departments/engineering/people/academic-staff/alan-ponter/papers.