On the necessity of using critical distance model in mixed mode brittle fracture prediction of V-notched Brazilian disk specimens under negative mode І conditions

Fracture load is experimentally measured for round-tip V-notched Brazilian disk (RV-BD) specimen made of PMMA and loaded under mixed mode І/ІІ with negative mode І components. The experimental results are obtained for 90° notch angle and various notch tip radii. The experimental observations show that in some cases, fracture does not initiate from the notch border and it occurs from the edge of the central square hole of the specimen, which is...