Nanoindentation Method for Measuring Residual Stress in Brittle Materials

Abstract

The lowered threshold load for cracking with the cube-corner indenter has been used in developing a method that can be used to measure residual stresses in small volume brittle materials. By studying a series of orthogonal cracks generated at loads not exceeding 10 mN with the cube-corner indenter, a variation of crack length with position around a large Vickers impression in soda-lime glass was observed. Using an indentation fracture mechanics approach residual stresses were evaluated at the positions where the cube-corner indents had been made. The stress values thus evaluated were generally higher than those reported in the literature where micro-Vickers indents had been used to measure the stresses. Possible reasons for the disparity are discussed.

Newly Discovered Pile Up Effects During Nanoindentation

“…Other researchers have tried using geometries to estimate the pile up [8,9], but a method of counting pixels was used in this study. ImageJ software was utilized by scaling the image based on the micron bar, and then measuring areas of the indents.…”

Radial Fracture During Indentation by Acute Probes: I, Description by an Indentation Wedging Model

“…However, cracking thresholds can be reduced dramatically, to as small as 1 mN in glasses and ceramics by employing a much more acute indenter -the cube-corner (Pharr et al, 1993). The increased damage-generating power of the cube-corner has led others to investigate fracture properties of thin films (Venkatesh et al, 2000;Li and Bhushan, 2001) and to utilize crack extension (or attenuation) as a method for residual-stress mapping on surfaces (Kese and Rowcliffe, 2003).…”

A technique for measuring stresses in small spatial regions using cube-corner indentation: Application to tempered glass plates

“…[15][16][17] In situ experiments reported in Ref. 17 show that cracking initiates almost instantaneously upon loading in glass, indicating that the threshold load is ∼0 N. Kese and Rowcliffe (K-R) 18 have proposed that the lowered threshold of cracking could be used to measure residual stresses in small volumes. They related the difference in crack length in a stressed and unstressed region to the stress state.…”