Quantitative understanding of single-asperity contact via molecular simulations

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Authors
Yang, Yongjian
Issue Date
2017-08
Type
Electronic thesis
Thesis
Language
ENG
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Materials engineering
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Abstract
In this thesis, I investigated single-asperity sliding and nanoindentation using molecular simulations. By tuning the interfacial adhesion and contact stress, it was found that there are two distinct wear modes (atomic wear and plastic wear) in terms of mathematical formulation, debris spatial orientation, and debris cluster size distribution. The transition from plastic wear to atomic wear can be also enhanced by adding lubricant. By controlling the sliding temperature, velocity and contact area, we found that atomic wear is shear-assisted, athermally-activated, and re- depositable. In a cluster analysis of atomic wear, we demonstrate a scaling behavior of the cluster distribution, which can be analogically understood by the critical phenomenon of phase transition. Through nanoindentation simulations, the crack initiation mechanism within a glassy material was revealed. The atomic insights obtained from our simulations will improve the quantitative reliability assessment for probe-based devices, help develop new crack resistant materials, and pave the way to quantitatively understand macroscopic wear and cracking.
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August 2017
School of Engineering
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Rensselaer Polytechnic Institute, Troy, NY
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