A modified MERR model for predicting mode II fracture initiation angle considering boundary constraint effect

Abstract

AbstractDuring the service process of brittle materials like marble, soda‐glass, and acrylic, mode II fracture is usually a typical failure mode. The fracture crack initiation, which is a critical factor affecting mode II fracture behavior, is an essential issue for understanding the fracture mechanism and determining fracture toughness. This paper proposed a modified maximum energy release rate model to predict the mode II fracture initiation angle through superimposing two idealized boundary conditions, remote loading, and crack‐face traction. The degree of the boundary constraint effect in finite‐size specimens was quantified by introducing the dimension‐ratio parameter. As experimentally validating through tension‐loading shear fracture tests of brittle poly(methyl methacrylate) (PMMA), the proposed model was demonstrated to be a good prediction of the mode II fracture initiation angle. The applicability of the proposed model was also verified with other brittle materials and fracture test techniques in references. The findings provide an insightful understanding of the mode II fracture behavior of brittle materials.