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Title: Analysis of indentation creep

Source: J. Mater. Res., Vol. 25, No. 4, Apr 2010, pp. 611-621; 2010

Author(s)Stone, Don S.; Jakes, Joseph E.; Puthoff, Johathan, Elmustafa, Abdelmageed A.

Publication Year: 2010  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4707-3A

Abstract: Finite element analysis is used to simulate cone indentation creep in materials across a wide range of hardness, strain rate sensitivity, and work-hardening exponent. Modeling reveals that the commonly held assumption of the hardness strain rate sensitivity (mH) equaling the flow stress strain rate sensitivity (ms) is violated except in low hardness/ modulus materials. Another commonly held assumption is that for self-similar indenters the indent area increases in proportion to the (depth)2 during creep. This assumption is also violated. Both violations are readily explained by noting that the proportionality 'constants' relating (i) hardness to flow stress and (ii) area to (depth)2 are, in reality, functions of hardness/modulus ratio, which changes during creep. Experiments on silicon, fused silica, bulk metallic glass, and poly methyl methacrylate verify the breakdown of the area-(depth)2 relation, consistent with the theory. A method is provided for estimating area from depth during creep.

Keywords: Materials, creep, hardness, deformations, nanostructured materials, measurement, nanotechnology, strains, stresses, mechanical properties, elasiticity, modulus of elasticity, metallic glasses, finite element method, testing, silicon, silica, polymethyl methacrylate, nanoindentation, flow stress strain rate sensitivity, hardness strain rate sensitivity, surface properties

Publication Review Process: Formally Refereed

File size: 599 kb(s)

Date posted: 05/17/2010

This publication is also viewable on Treesearch:  view
RITS Product ID: 33963
Current FPL Scientist associated with this product
Jakes, Joseph
Research Materials Engineer

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