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Title: Measuring residual stress in glasses and ceramics using instrumented indentation.

Abstract

Instrumented indentation has yielded mixed results when used to measure surface residual stresses in metal films. Relative to metals, many glasses and ceramics have a low modulus-to-yield strength (E/sy) ratio. The advantage of this characteristic for measuring residual stress using instrumented indentation is demonstrated by a series of comparative spherical and conical tip finite element simulations. Two cases are considered: (i) a material with E/s{sub y} = 24-similar to glass and (ii) a material with E/s{sub y} = 120-similar to metal films. In both cases, compressive residual stress shifts the simulated load-displacement response toward increasing hardness, irrespective of tip geometry. This shift is shown to be entirely due to pile up for the ''metal'' case, but primarily due to the direct influence of the residual stress for the ''glass'' case. Hardness changes and load-displacement curve shifts are explained by using the spherical cavity model. Supporting experimental results on stressed glasses are provided.

Authors:
;
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
908710
Report Number(s):
SAND2007-2087J
TRN: US200722%%759
DOE Contract Number:
AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proposed for publication in the Journal of Materials Research.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERAMICS; GLASS; HARDNESS; RESIDUAL STRESSES; FILMS; SURFACE PROPERTIES; FINITE ELEMENT METHOD

Citation Formats

Tandon, Rajan, and Buchheit, Thomas E. Measuring residual stress in glasses and ceramics using instrumented indentation.. United States: N. p., 2007. Web.
Tandon, Rajan, & Buchheit, Thomas E. Measuring residual stress in glasses and ceramics using instrumented indentation.. United States.
Tandon, Rajan, and Buchheit, Thomas E. Thu . "Measuring residual stress in glasses and ceramics using instrumented indentation.". United States. doi:.
@article{osti_908710,
title = {Measuring residual stress in glasses and ceramics using instrumented indentation.},
author = {Tandon, Rajan and Buchheit, Thomas E.},
abstractNote = {Instrumented indentation has yielded mixed results when used to measure surface residual stresses in metal films. Relative to metals, many glasses and ceramics have a low modulus-to-yield strength (E/sy) ratio. The advantage of this characteristic for measuring residual stress using instrumented indentation is demonstrated by a series of comparative spherical and conical tip finite element simulations. Two cases are considered: (i) a material with E/s{sub y} = 24-similar to glass and (ii) a material with E/s{sub y} = 120-similar to metal films. In both cases, compressive residual stress shifts the simulated load-displacement response toward increasing hardness, irrespective of tip geometry. This shift is shown to be entirely due to pile up for the ''metal'' case, but primarily due to the direct influence of the residual stress for the ''glass'' case. Hardness changes and load-displacement curve shifts are explained by using the spherical cavity model. Supporting experimental results on stressed glasses are provided.},
doi = {},
journal = {Proposed for publication in the Journal of Materials Research.},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}
  • Abstract not provided.
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  • Instrumented indentation and thermal wave techniques are used as local, quantitative probes of microcrack density in a silicon nitride that has been subjected to severe Hertzian contact stress. The techniques act as local probes, sampling volumes of material <10{sup {minus}3} mm{sup 3}. Microcracked regions are created using a tungsten carbide spherical indenter, as a result of high shear stress in the compressive zone beneath the indenter. The microcracked zones, studied in cross section using a ``bonded interface`` technique, increased both in size and in degree of damage with increasing Hertzian load. Within the zones, Young`s modulus is measured using instrumentedmore » indentation, and the thermal diffusivity using a thermal wave technique; both quantities are lower in the damaged regions than in the undamaged regions. The shifts in modulus and diffusivity are used independently to calculate microcrack densities using related models of the effect of microcracks on each property. The two techniques show the same functional relationship between Hertzian contact load and microcrack density, and yield densities that agree to within a factor of approximately 2.« less
  • We present a measurement scheme for creating reference electrostatic forces that are traceable to the International System of Units. This scheme yields reference forces suitable for calibrating the force sensitivity of instrumented indentation machines and atomic force microscopes. Forces between 10 and 200 {mu}N were created and expressed in terms of the voltage, length, and capacitance between a pair of interacting electrodes. The electrodes comprised an electrically conductive sphere mounted as a tip on an instrumented indentation sensor, and a planar counterelectrode fixed to a sample stage in close proximity to the sphere. For comparison, we applied mechanical forces ofmore » similar magnitudes, first using deadweights and then using a reference force sensor. The deflection of the sensor due to the various applied forces was measured using an interferometer. A spring constant for the sensor was computed from the observed records of force versus displacement. Each procedure yielded a relative standard uncertainty of approximately 1%; however, the electrostatic technique is scalable and could provide traceable reference forces as small as a few hundred piconewtons, a range far below anything yet achieved using deadweights.« less
  • A review of the observations of indentation-induced fracture suggests that there is no simple generalization which may be made concerning crack initiation sequences. A detailed consideration of the stress fields arising during indentation contact predicts material-dependent initiation sequences, in agreement with observations, particularly those of radial crack formation on loading for materials with large modulus-to-hardness ratios. In addition, a new, unexplored crack system is demonstrated, the shallow lateral cracks, which appear to be responsible for material removal at sharp contacts.