In this paper, in order to predict the crack growth direction and fracture load under mixed modes I and II loading, a new criterion is proposed. For this purpose, after reviewing existing criteria, an effective stress is defined so as to include the influential stress components in fracture and exclude insignificant ones. Moreover, investigations show that most criteria predict a certain angle of fracture in pure mode II independent of material properties, although the experimental results are noticeably different for various materials. To solve this problem, effects of the ratio of fracture toughness for pure mode II to that of pure mode I are considered by defining a new material parameter. To verify the suggested criterion, after characterization of the newly defined material parameter, the predicted values using this criterion for the mixed‐mode conditions are computed. The predicted results show a good agreement with the experimental results.

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In this paper, a new brittle fracture criterion was developed to predict the fracture in sharp V-shaped notches. This criterion, by defining a quantity called "V-shaped notch effective stress," takes into account the effect of the shear stress in addition to the tangential stress. The initial crack criterion, which lays the foundation for developing this criterion, has yielded remarkable results for a broad spectrum of brittle materials in the entire range of mixed-mode I/II loading conditions. This development helps to employ a novel criterion for V-shaped notches with the capability of being used in the entire range of mixed-mode I/II loading conditions. The outcomes of the two other valid criteria and multiple experimental results were compared with the developed criterion results to validate it. The developed criterion's predicted results revealed a strong correlation with experimental results, particularly in conditions where mode II loading was predominant.

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