True Mode $$\mathrm {III}$$ Fracturing of Rocks: An Axially Double-Edge Notched Brazilian Disk Test

Abstract A new test, referred to as axially double-edge notched Brazilian disk (ANBD), is proposed measure true mode $$\mathrm {III}$$ III fracture toughness ( $$K_{\mathrm {IIIc}}$$ K IIIc ) of rock materials. The term denotes a shear-induced fracturing via self-planar crack extension opposed twisted tension-based one commonly observed in many experiments rocks. ANBD test follows straightforward procedure thanks its simple core-based geometry and diametrical compression loading setup. Finite element analyses are employed evaluate the stress intensity variations along front calculate point-wise factors (SIFs) for different configurations. results tests conducted on granitic samples demonstrate good performance this yielding fracturing. influences parameters ligament length angle also investigated. comparison study shows that values similar {IIc}}$$ IIc but almost 2.5 times greater than {Ic}}$$ Ic . This demonstrates offers shear-based mechanism {II}$$ II , which significantly more energy-consuming {I}$$ I failure type.