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Factors affecting reversible shape-memory.

Friend, C. M. (1985) Factors affecting reversible shape-memory. Doctoral thesis, University of Surrey (United Kingdom)..

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In the last twenty years Reversible Shape-Memory (RSM) alloys have become the source of considerable technological interest as a result of their ability to generate spontaneous and reversible changes of shape on thermal cycling. This has led to the development of a range of reversible shape-memory devices for thermostatic sensing applications. In these devices the alloy is subjected to several thousand shape-memory cycles and the stability of the reversible shape-memory is therefore an important alloy property. Data on the effect of shape-memory cycling on the long-term stability of the reversible shape-memory, however, is extremely limited. The present work, conducted to fill this gap, has shown that there is an inherent instability in the reversible shape-memory, with changes in the operating temperatures and cumulative reductions in the maximum shape-strain output of actuators on long-term thermal cycling under conditions simulating real devices. Extensive investigation has shown that these instabilities result from a number of sources, ageing of the shape-memory martensites and most importantly from morphological disruptions in the "trained" martensites caused by two-stage stress-induced transformation and due to the build-up of transformation-induced dislocation debris. This shape-strain degradation has also been successfully modelled by means of a simple two-stage stress-induced martensitic transformation model.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Friend, C. M.
Date : 1985
Contributors :
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1985.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 13:01
Last Modified : 06 Nov 2018 16:52

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