Fractional analysis of wood fracture surface based on image processing

Quantitative studies on the fracture surfaces of three-point bending fracture and impact fracture for the common timber ashtree were launched using the fractal theory, the fractal feature of wood fracture was explored and the fracture mechanism of wood fracture was analyzed quantitively. In the study, computer image processing technology is employed to extract the image information of fracture surface both in macro and micro views; and the fractal dimension of fracture surface is calculated with Slit Island Analysis. Moreover, the relationships between fractal dimensions and MOE, bending strength as well as impact toughness are analyzed. The results show that the wood fracture surface within a limited dimension has remarkable self-similarity and fractal feature. The fractal dimension of the SE (B) samples is 2.601 2 and is higher than that of the WL samples, which is 2.566 3, but the MOE and bending strength of the SE (B) samples are 6.17 MPa and 105.17 Mpa, respectively, and are lower than those of the WL samples, which are 7.08 MPa and 109.18 MPa, respectively. There exists significant linear correlation between fractal dimension and bending strength, but the linear correlation between fractal dimension and MOE is not obvious. The fractal dimension of wood impact fracture surface is 2.607 8 and is higher than that of bending fracture surface, which is 2.566 3, but is close to the fractal dimension of three-point bending fracture surface of SE (B) samples, which is 2.601 2. Moreover, for the timber ashtree, there exists significant linear correlation between fractal dimension and impact toughness as well as fracture toughness.