ON ESTIMATING PLASTIC ZONES AND PROPAGATION ANGLES FOR MIXED MODE I/II CRACKS CONSIDERING FRACTAL EFFECT

This paper mainly investigated the influence of the fractal dimension of mixed mode I/II crack on its near-tip plastic zones and propagation angles. The near-tip distortional strain energy density for mixed mode I/II crack is modified by considering its fractal dimension. Using the Von Mises yield condition, the plastic zones at the fractal crack tip are evaluated. The effects of the fractal dimension of crack on the near-tip plastic zones are analyzed qualitatively. A modified criterion minimizes the fractal distortional strain energy density to predict the propagation direction of mixed mode I/II crack. Based on this, the effects of fractal dimension on the mixed mode I/II crack propagation direction at different inclination angles are discussed quantitatively. In addition, the modified criterion is compared to the experimental data in the literature, as well as the classical maximum tangential stress criterion and minimum strain energy density criterion. The results indicate that the fractal dimension of crack is an important factor in evaluating the crack-tip plastic zones and predicting the crack propagation angle, and the modified fractal criterion is more accurate and effective in predicting the crack propagation angles.