Description
- Abstract:
- Solid-surface contact suspension is governed by asperity contact strength and multi-frequency surface roughness. Both of these two aspects are examined in this thesis for tribological application of the solid-surface suspension technique. The research is divided into three parts. Part I focuses on the size-dependent contact strength of nano-asperities. Contact strength of nano-asperities is proposed to be mainly governed by heterogeneous dislocation nucleation due to the contact edge singularity. The dislocation model predicts that a single crystal gold pyramid with [114] facets has a contact strength scaling exponent of -0.497, which is in good agreement with the existing MD simulation result. In Part II, a novel hybrid method of nanoindentation and finite element analysis is used to characterize the silicon particle suspension resistance and the mechanical properties of Al/Si interface in an aluminum matrix composite. The suspension resistance is found to be strongly dependent on the aspect ratio, up to 2, of the buried portion of cylindrically shaped particles. The resistance comes from the plastic-flow strength of the matrix and the slip strength of the interface. The interface is found to be separated during unloading. An element-size dependent FEM cohesive-zone law is used to extract the interface properties; the results compare well with atomistic calculations. The final part of this thesis is an experimental study on micro-slip friction laws of rough surface contact with a direct quantitative measurement of the interfacial slip zone using electronic speckle pattern interferometry (ESPI). A slip precursor displacement of about 3 microns is measured before the onset of macro-slip of two contact PMMA surfaces with 1 micron RMS roughness. An apparent penetration depth under normal pressure is further observed with a contact stiffness of about 6 MPa/micron.
- Notes:
- Thesis (Ph.D.) -- Brown University (2008)
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Citation
Xia, Shuman,
"Micromechanics of solid-surface contact suspension and its role in friction"
(2008).
Engineering Theses and Dissertations, Mechanics of Solids Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0S180SW
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Mechanics of Solids Theses and Dissertations
Theses and Dissertations for the Mechanics of Solids department....