NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
THE COMPELLING CASE FOR INDENTATION AS A FUNCTIONAL EXPLORATORY AND CHARACTERIZATION TOOL
Published
Author(s)
Robert F. Cook, David B. Marshall, Nitin P. Padture, Michelle L. Oyen, Antonia Pajares, Jodie E. Bradby, Ivar E. Reimanis, Rajan Tandon, Trevor F. Page, George M. Pharr, Brian R. Lawn
Abstract
The utility of indentation testing for characterizing a wide range of mechanical properties of brittle materials is highlighted in light of recent articles questioning its validity, specifically in relation to the measurement of toughness. Contrary to assertion by some critics, indentation fracture theory is fundamentally founded in GriffithIrwin fracture mechanics, based on model crack systems evolving within inhomogeneous but well-documented elastic and elasticplastic contact stress fields. Notwithstanding numerical inaccuracy in associated stress intensity factor relations, the technique remains an unrivalled quick, convenient and economical means for comparative, site-specific toughness evaluation. Most importantly, indentation patterns are unique fingerprints of mechanical behavior and thereby afford a powerful functional tool for exploring the richness of material diversity. At the same time, it is cautioned that unconditional usage without due attention to the conformation of the indentation patterns can lead to overstated toughness values. Limitations of an alternative, more engineering approach to fracture evaluation, that of propagating a pre-crack through a 'standard' machined specimen, are also outlined. Misconceptions in the critical literature concerning the fundamental nature of crack equilibrium and stability within contact and other inhomogeneous stress fields are discussed.
Cook, R.
, Marshall, D.
, Padture, N.
, Oyen, M.
, Pajares, A.
, Bradby, J.
, Reimanis, I.
, Tandon, R.
, Page, T.
, Pharr, G.
and Lawn, B.
(2015),
THE COMPELLING CASE FOR INDENTATION AS A FUNCTIONAL EXPLORATORY AND CHARACTERIZATION TOOL, Journal of the American Ceramic Society, [online], https://doi.org/10.1111/jace.13729
(Accessed October 14, 2025)