Experimental and Theoretical Study of Fracture Paths in Brittle Cracked Materials Subjected to Pure Mode II Loading

Abstract

Crack growth path was investigated experimentally, numerically and theoretically using two test specimens subjected to pure mode II loading. The specimens were (a) the center cracked circular disc (CCCD) specimen subjected to diametral compression often called the Brazilian disc and (b) the diagonally loaded square plate (DLSP) specimen containing inclined center crack and subjected to pin loading. A few CCCD and DLSP specimens made of two brittle materials (i.e. marble rock and PMMA) were tested under pure mode II conditions. It was observed that the fracture initiation directions and the fracture paths for the tested specimens differed significantly and grew in two different trajectories. However, it was shown that the experimentally observed fracture paths for both specimens can be predicted theoretically very well by using the incremental crack growth method. Several finite element analyses were performed to simulate the whole fracture trajectories of the tested CCCD and DLSP specimens. At each increment, the direction of fracture initiation for the tip of growing crack was determined using the fracture parameters (i.e. stress intensity factors and T-stress) based on the modified maximum tangential stress (MMTS) criterion. The main difference in the fracture trajectory was found to be related to the magnitude and sign of the fracture parameters (which depend strongly on the specimen geometry and loading configuration) and also the type of tensile or compressive loading in the CCCD and DLSP samples.

Finite element-based model for crack propagation in linear elastic materials

“…The maximum circumferential stress or strain criterion, the maximum energy release rate criterion, the minimum strain energy density criterion and the maximum circumferential stress criterion can be used to determine the direction of crack propagation, as stated in different papers (Belytschko & Black, 1999;Ayatollahi et al, 2006Ayatollahi et al, , 2011Khan & Khraisheh 2000, 2004Ayatollahi & Aliha 2007, 2009Mirsayar et al, 2014, Akbardoost et al, 2014Aliha et al, 2010Aliha et al, , 2016aAliha et al, ,b, 2017Razavi et al, 2018, Abd-Elhady, 2013Aliha & Ayatollahi 2008, 2012, Xie & Waas 2006Aliha & Saghafi 2013;Dehghany et al, 2017, Sutton et al, 2000Cooke & Pollard, 1996;Aliha & Rezaei, 2011;Matvienko, 2012). In present study the maximum circumferential stress criterion is exploited for isotropic materials under mixed-mode loading.…”

Dynamic response and damage evolution of red sandstone with confining pressure under cyclic impact loading

“…However, the effect of T‐stress is not considered in the traditional conventional criteria. On the one hand, the T‐stress has been confirmed to have a correlation with the value of fracture toughness and the direction of fracture initiation for the tip of the growing crack 17,18 ; on the other hand, a semielliptical fracture process zone develops ahead of the crack tip. The calculation of the T‐stress and fracture process zone depend on the length of the cracks.…”

Crack growth path prediction for the angled cracked plate using higher order terms of Williams series expansion

“…Due to the continuous deformation of a crack relative to its initial shape, the use of numerical analyses such as finite element method is often necessary for modeling the trajectory of growing cracks. For example, Ayatollahi et al (2006), Aliha et al (2010Aliha et al ( , 2012 and Aliha and Rezaei (2011) determined numerically mixed mode fracture path of some test specimens using the finite element simulations by means of the incremental crack growth method.. However In the second method (i.e the fracture threshold method), regardless of any progressive growth of the crack, the crack growth path is estimated based on the distribution of mechanical parameters such as stress, strain or similar parameters at the onset of failure.…”