Understanding the linear relation between pop-in excursion length and critical force for spherical nanoindentation

Funding Number

11872139

Funding Sponsor

National Natural Science Foundation of China

Second Author's Department

Mechanical Engineering Department

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https://doi.org/10.1080/14786435.2021.1902588

Document Type

Research Article

Publication Title

Philosophical Magazine

Publication Date

1-1-2021

doi

10.1080/14786435.2021.1902588

Abstract

Pop-in is a widely observed phenomenon in nanoindentation. In this paper, dislocation evolution in pop-in processes is analysed in detail through molecular dynamics (MD) simulations. We found that a large number of dislocations nucleate homogeneously at the initiation of pop-in, followed by extensive dislocation propagation, which is the dominant mode of plastic deformation during pop-in. Moreover, we noted that establishing the correct dislocation evolution mechanisms of pop-in can serve to explain the overshoot phenomenon observed in nanoindentation experiments. Through our MD analysis on the obtained dislocation structures, therefore, we were able to propose a model that can predict the total length of dislocations associated with the plastic processes underneath a spherical indenter. In addition, the Taylor model was used to verify that our proposed dislocation length model sits well with the MD simulated force-displacement curves of nanoindentation. In fact, the MD simulated linear relation between critical force and indentation depth during pop-in is consistent with the Hertzian and Taylor models. Our MD simulations, therefore, can provide significant insight into the experimentally observed pop-in phenomena.

First Page

1343

Last Page

1363

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