A model to predict the fractal dimension of fractured surfaces of 7075 aluminium alloys based on Koch's fractal curve and mechanical properties

The fractal dimension, D-f, of the fractured surfaces of four 7075-T651 aluminium alloys, was calculated using a model which combines the concept of Koch's broken line and the notion of K-IC-mechanical properties relationship. D-f is expressed in terms of the average grain size, the number of dimples equivalent to an average grain size, the yield strength, the ultimate tensile strength, the strain hardening exponent and K-IC There was a good agreement between the experimental values of D-f and those obtained from the proposed model. The relationship between D-f and K-IC, reveals this two tendencies: for low values of K-IC, an increase in D-f accompanies an increase in fracture toughness, whereas for high enough K-IC values, this tendency is changed to a negative one.