Measuring Nanoscale Stress Intensity Factors with an Atomic Force Microscope

Atomic Force Microscope images of a crack intersecting the free surface of a glass specimen are taken at different stages of subcritical propagation. From the analysis of image pairs, it is shown that a novel Integrated Digital Image Correlation technique allows to measure stress intensity factors in a quantitative fashion. Image sizes as small as 200 nm can be exploited and the surface displacement fields do not show significant deviations from linear elastic solutions down to a 10 nm distance from the crack tip. Moreover, this analysis gives access to the out-of-plane displacement of the free surface at the crack tip.