Digital image correlation was used to identify the process zone by measuring incremental displacement contours and profiles at different crack configurations. Smooth boundary specimens of Berea sandstone, average grain size of 0.2 mm, were studied in the three-point bend test, such that fracture occurred within a specimen without a macroscopic stress concentrator (no-notch specimens). The experimental results were related to the incremental displacement field due to the initiation and propagation of a mode I fracture. The change in crack opening displacement between two different crack configurations provided the basis to interpret the process-zone length, which was estimated to be 5 - 7 mm or about 30 times the average grain size. The length remained more or less constant (5 - 7 mm) with crack propagation in the post-peak region.
|Original language||English (US)|
|State||Published - Dec 6 2011|
|Event||45th US Rock Mechanics / Geomechanics Symposium - San Francisco, CA, United States|
Duration: Jun 26 2011 → Jun 29 2011
|Other||45th US Rock Mechanics / Geomechanics Symposium|
|City||San Francisco, CA|
|Period||6/26/11 → 6/29/11|