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Dislocation dynamical approach to force fluctuations in nanoindentation experiments

Ananthakrishna, G and Katti, Rohit and Srikanth, K (2014) Dislocation dynamical approach to force fluctuations in nanoindentation experiments. In: PHYSICAL REVIEW B, 90 (9).

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Official URL: http://dx.doi.org/ 10.1103/PhysRevB.90.094104

Abstract

We develop an approach that combines the power of nonlinear dynamics with the evolution equations for the mobile and immobile dislocation densities and force to explain force fluctuations in nanoindentation experiments. The model includes nucleation, multiplication, and propagation thresholds for mobile dislocations, and other well known dislocation transformation mechanisms. The model predicts all the generic features of nanoindentation such as the Hertzian elastic branch followed by several force drops of decreasing magnitudes, and residual plasticity after unloading. The stress corresponding to the elastic force maximum is close to the yield stress of an ideal solid. The predicted values for all the quantities are close to those reported by experiments. Our model allows us to address the indentation-size effect including the ambiguity in defining the hardness in the force drop dominated regime. At large indentation depths, the hardness remains nearly constant with a marginal decreasing trend.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Depositing User: Id for Latest eprints
Date Deposited: 26 Sep 2014 11:03
Last Modified: 26 Sep 2014 11:03
URI: http://eprints.iisc.ac.in/id/eprint/49964

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