Relaxation oscillations and negative strain rate sensitivity in the Portevin–Le Chatelier effect

Rajesh, S and Ananthakrishna, G (2000) Relaxation oscillations and negative strain rate sensitivity in the Portevin–Le Chatelier effect. In: Physical Review E, 61 (4). pp. 3664-3674.

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Abstract

A characteristic feature of the Portevin–Le Chatelier effect, or the jerky flow, is the stick-slip nature of stress-strain curves which is believed to result from the negative strain rate dependence of the flow stress. The latter is assumed to result from the competition of a few relevant time scales controlling the dynamics of jerky flow. We address the issue of time scales and its connection to the negative strain rate sensitivity of the flow stress within the framework of a model for the jerky flow, which is known to reproduce several experimentally observed features, including the negative strain rate sensitivity of the flow stress. We attempt to understand the above issues by analyzing the geometry of the slow manifold underlying the relaxational oscillations in the model. We show that the nature of the relaxational oscillations is a result of the atypical bent geometry of the slow manifold. The analysis of the slow manifold structure helps us to understand the time scales operating in different regions of the slow manifold. Using this information we are able to establish connection with the strain rate sensitivity of the flow stress. The analysis also helps us to provide a proper dynamical interpretation for the negative branch of the strain rate sensitivity.

Item Type:	Journal Article
Publication:	Physical Review E
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	01 Aug 2006
Last Modified:	19 Sep 2010 04:30
URI:	http://eprints.iisc.ac.in/id/eprint/7975

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