Relationship between Fractal Geometry and Fractography |
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Authors: | John J Mecholsky Jr Stephen W Freiman |
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Affiliation: | Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611;National Institute of Standards and Technology, Galthersburg, Maryland 20899 |
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Abstract: | Fractal geometry has been used to describe irregular fracture surfaces in a quantitative way. The fractal dimensional increment has been related to the fracture toughness of the material through the elastic modulus and a characteristic structure parameter, a 0. The study of fractography has shown the relationship between the flaw/mirror size ratio and the fracture toughness. An experimental observation has shown that the fracture toughness is related to the elastic modulus through another structure parameter, b 0. Combining all of these relationships leads to the conclusion that the fractal dimensional increment, D *, is directly related to the flaw/mirror size ratio. Experimental measurements of the fractal dimension and the flaw/mirror size ratio on glasses, a glass-ceramic, polycrystalline ceramics, and a single crystal all agree with the prediction. The implication of this finding is that there is a linear scaling law in operation at fracture between the energy of crack initiation and of microbranching and is reflected in the features on the fracture surface. |
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Keywords: | fractal geometry fractography cracks flaws |
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