Mixed-mode I/II fracture criteria proposed for cracked orthotropic materials: A special overview on the efficiency of reinforced isotropic solid (RIS) model in enhancing predictive accuracy

The assessment method for the residual strength and resistance of cracked orthotropic materials under in-plane tensile-shear loading involves the application of mixed-mode I/II fracture criteria specifically developed for these materials. In fracture mechanics, various criteria are used to analyze crack growth behavior and load-bearing capacity, which can be based on strength, stress, strain, or energy approaches. In this research an analytical review of mixed-mode I/II fracture criteria is performed to identify a suitable and superior criterion for predicting the fracture behavior of cracked orthotropic materials. Selecting an appropriate material model is essential, as it can significantly enhance the accuracy of the results. Given the critical importance of the chosen material model in analyzing crack propagation, this study explores the fracture criteria proposed for evaluating the fracture of cracked orthotropic materials, alongside a reinforced isotropic solid (RIS) model, which is recognized as a superior approach. The predicted fracture behavior for each criterion is compared using fracture limit curves to find the best alignment with experimental data. Additionally, this paper reviews a wide range of fracture criteria with various characteristics, including cases where the crack forms an arbitrary angle with respect to the fibers. It also considers the T-stress term, which significantly affects the crack propagation angle, as well as the damage zone at the crack tip and fracture resistance. The proposed optimal criterion will be identified based on the percentage of error in the fracture envelope curves compared to the available experimental data.