Mixed mode fracture analysis of CCBD specimens based on the extended maximum tangential strain criterion

Abstract

The maximum tangential strain (MTSN) criterion has been modified to include the effects of T‐stress and stress intensity factors in conditions of both plane stress and plane strain. Further, both the T‐stress and Poisson's ratio affecting the crack propagation are also discussed according to the extended MTSN (EMTSN) criterion, which is a modified MTSN criterion. Finally, the generalized maximum tangential stress (GMTS) criterion and the EMTSN criterion are used to predict the test results obtained with central cracked Brazilian disc (CCBD) specimens. The results indicate that the T‐stress and Poisson's ratio have a remarkable influence on the mixed mode fracture resistance based on the EMTSN criterion. Theoretical values of both the EMTSN and the GMTS criteria are in very good agreement with the test results. Moreover, the EMTSN criterion provides a better prediction for pure mode II.

Modes I/II SIF of a diametrically compressed Brazilian disc having a central inclined crack with frictional surfaces

“…In this regard, amongst the well‐known test specimens is the centrally cracked Brazilian disc (CCBD) under a concentrated diametrically compressive load. It provides a simple and effective technique to evaluate in‐plane shear and mixed mode I/II fracture of different materials …”

“…It provides a simple and effective technique to evaluate in-plane shear and mixed mode I/II fracture of different materials. [10][11][12][13][14][15][16][17][18] The CCBD specimen has a simple geometry and loading arrangement and, further, the capability of applying various mixed modes by changing the precrack inclination angle relative to the applied diametric load. For an inclined crack in compression, different regimes of contact between its surfaces can arise.…”

Experimental Study on Mixed Mode Fracture Behavior of Sandstone under Water–Rock Interactions

“…Mirsayar [54] proposed a similar strain-based criterion and employed it to evaluate the fracture mechanical behavior of polymethyl methacrylate. Hua et al [50] extended the GMTSN criterion by considering both plane strain and plane stress conditions, and made use of it to evaluate the brittle fracture behaviors of the CCBD specimens made of graphite and rock materials. More recently, the GMTSN criterion has been frequently employed to evaluate the onset of the fracture of different materials [51,[55][56][57].…”

“…More recently, the GMTSN criterion has been frequently employed to evaluate the onset of the fracture of different materials [51,[55][56][57]. Based on the GMTSN criterion [50,53,54], the crack initiation angle (θ0) can be calculated using the following formula: The treatment procedure of cyclic wetting-drying in this experiment actually included not only wetting and drying, but also heating and cooling processes. After soaking, the sandstone samples were heated in an oven.…”

“…Moreover, κ is a coefficient for distinguishing the plane strain or plane stress condition, which is associated with the Poisson's ratio ν. For the plane stress problems, the value of the coefficient κ is equal to 1/(1 + ν), whereas its value is 1 − ν for the plane strain problems [50]. Similarly, based on the GMTSN criterion [50], the onset of brittle fracture can be determined from the following equations:…”