Authors: F Dai M D Wei N W Xu Y Ma D S Yang
Publish Date: 2014/04/22
Volume: 48, Issue: 2, Pages: 463-479
Abstract
The International Society of Rock Mechanics ISRM suggested cracked chevron notched Brazilian disc method falls into a major testing category of rock fracture toughness measurement by virtue of chevron notched rock samples A straight through crack front during the whole fracturing process is assumed in the testing principle but is never assessed In this study the progressive rock fracture mechanism of cracked chevron notched Brazilian disc rock specimens is numerically simulated for the first time Two representative sample types with distinct geometry of notch ligaments are modelled The assumption of a straight through crack front for chevron notched fracture samples is critically assessed The results show that not only the notch tip but also the sawcut chevron notch cracks during the experiments The straight through crack front assumption is never satisfied in the realistic rock fracture progress of chevron notched disc samples In addition the crack features prominent curved front far from being straight In contrast to the sample type with narrow notch ligament the acoustic emission AE of the simulation on the sample with wide notch ligament depicts obvious biased fracturing of the prescript fracturing route of the notch The numerically observed progressive fracture mechanism calls for more attention on how to accurately calibrate the critical dimensionless stress intensity factor for a better measurement of Mode I fracture toughness via chevron notched samplesThe authors are grateful for the financial support from the National Natural Science Foundation of China Nos 51374149 and 51209127 the Program for New Century Excellent Talents in University NCET130382 and the Doctoral Fund of Ministry of Education of China No 20130181110044
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