Finite Element Analysis of Mixed-Mode I/II Fracture in Marble Using SENB Specimens

Abstract

The fracture behavior of brittle rocks, like fractures in marble, is important for various engineering applications, including mining, underground facilities, hydraulic mining, and tunneling. While most of the prior work has focused on pure Mode I loading, rock structures undergo mixed-Mode I/II loading in which fractures appear from tensile and shear stresses. This research specifically looks at mixed-Mode I/II fractures in which vertical pre-cracked single edge notched beam specimens allow for a variety of Mode mixites without the difficult construction of angled cracks. Finite element simulations in ABAQUS focused on calculating Mode I (KI) as well as II (KII) stress intensity factors (SIF) and T-stress, with mesh convergence ensuring accuracy. To predict fractures in polygons, the maximum tangential stress (MTS) and generalized maximum tangential stress (GMTS) criteria were used. The outcomes display that pure Mode I yields the lowest fracture load while, with Mode II contribution, it increases and reaches the peak at pure Mode II. There is an increase in the crack propagation angle with respect to the increase of Mode II dominance, displaying the effect of negative T-stress on cracking density. The methodology is single-edge notched beam (SENB) samples for the mixed-mode fracture of brittle rocks incorporating numerical simulations with fracture criteria. This gives systems for predictive modelling to work with in experimental design.