Analysis of Crack-Tip Field in Orthotropic Compact Tension Shear Specimens: The Role of Elastic Mode Mixity and T-Stress

The analysis of mixed-mode crack propagation mechanisms in anisotropic materials remains a pivotal research focus. Although the compact tension shear (CTS) test is a recommended laboratory method, the lack of solutions for anisotropic crack-tip field parameters hinders accurate assessment of stress states and deformations during crack propagation. To address this gap, this study conducted a systematic finite element analysis (FEA) to compute the elastic mode mixity and T-stress results. It is found that by adjusting the loading angle along with the initial crack length, CTS tests on orthotropic specimens can similarly achieve a broad spectrum of M_e at the crack-tip. Statistical analysis indicates that applying isotropic solutions to estimate orthotropic T-stress can lead to average errors of 234.1%. Subsequently, crack-tip fields were analyzed, with crack initiation angles predicted using the maximum tangential stress (MTS) criterion and plastic zone profiles determined based on Hill's yield criterion. Larger fracture process zones enhance T-stress correction effects on crack initiation angles, with positive T intensifying crack deflection, while negative T reduces it. Additionally, T also significantly affects the plastic zone's shape and size, with patterns varying according to material orthotropy. A detailed multiparameter characterization of crack-tip fields will enhance the use of the CTS test for assessing multiaxial strength and mixed-mode fracture mechanisms in anisotropic materials.