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Effect of the Spherical Indenter Tip Assumption on the Initial Plastic Yield Stress

Published

Author(s)

Li Ma, Lyle E. Levine, Ronald G. Dixson, Douglas T. Smith, David Bahr

Abstract

Nanoindentation is widely used to explore the mechanical properties of small volumes of materials. For crystalline materials, there is a growing experimental and theoretical interest in pop-in events, which are sudden displacement-burst excursions during load-controlled nanoindentation of relatively dislocation-free metals. The first pop-in event is often identified as the initiation of dislocation nucleation, and thus the transition from purely elastic to elastic/plastic deformation. The maximum shear stress at this first pop-in event, or the onset of plastic yielding, is generally found to be close to the theoretical strength of the material and is frequently estimated from Hertzian elastic contact theory. However, an irregular indenter tip shape will significantly change the stress distribution in magnitude and location, and therefore the maximum shear stress, from a Hertzian estimation. The aim of this chapter is to state the challenges and limitations for extracting the initial plastic yield stress from nanoindentation with the spherical indenter tip assumption. We assess possible errors and pitfalls of the Hertzian estimation of initial plastic yield at the nanoscale.
Citation
Nanoindentation
Publisher Info
InTech - open science | open minds, Rijeka, -1

Citation

Ma, L. , Levine, L. , Dixson, R. , Smith, D. and Bahr, D. (2012), Effect of the Spherical Indenter Tip Assumption on the Initial Plastic Yield Stress, Nanoindentation, InTech - open science | open minds, Rijeka, -1, [online], https://doi.org/10.5772/48106 (Accessed May 20, 2024)

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Created October 17, 2012, Updated November 10, 2018